My truck is giving th p0380 DTC code.. after alot of research i have about come to the conclusion that it is the glow plug relay... Does anyone know where i can get this part or a link to one or a part number?? Thanks

If it is a federal emissions truck, then yes it is most likely the relay. You can go to GM and buy the complet controller for about $70, or just 1 relay is almost $120(and there is 2 relays in it). I went down to CARQUEST myself and ordered a 70 amp FORD relay from them for $11 and have had good luck with it.

How would you instal the 70amp relay and can someone tell me where this relay is located? 11$ Is cheap I would do it tommorow if i knew where it was and how to do it.

I removed the glow plug controller and the cover comes off of it. Once you get the cover off you'll see the 2 relays inside of it, one is intake heater and the other is glow plug. Just find the relay that is hooked to the post for the glow plugs and change that one. Most likely you'll see the burn marks on the side of it of melted polastic from where the points failed.

Ok well where abouts is the glow plug controller? I know my wiring harness for the intake heater is alittle beat up melted and stuff where from ther is it

i have the same po380 code and my ses light is intermittent. possible relay? i took it apart and the wiring and relay's appears to be okay. any thoughts?

i took mine apart and everything looked "ok" but the relay itself or maybe even the wire coming from it was shot. i replaced the controler and haven't had any trouble since.

The gow plug relay is mounted on the drivers side valve cover at the very rear behind the turbo outlet pipe. It's a small black plastic box with a 4 wire plug on top of it and then 3 large studs with big cables hooked to it. The relays in it are sealed and you cannot inspect the points inside of them.

The relay I sued was CARQUEST number 56-2335, and the FORD numbers on it are F80B-14B192-AA. the actual FORD part number is F8OZ-14N089-AA i found from a google search, but FORD lists it for $28.

How hard is it to get the glow plug controller off??

I got the glow plug controller for my 2001 Dmax from gmpartsdirect. August 21 2009, it was $46.28. Now I see they have it listed at $67.58. So, that kind of blows.

Part# 97371491 is what I got (Fed emissions) and it fixed me right up. I had the same P0380 code.

Easy to replace, 2 beer job with just a couple sockets.

Thanks alot!!! This seems to be a real common code and problem but it seems like everybody is still searching for a simple solution or something just because there truck is still running... I don't know about them but i feel like i;m abusing my truck because when i do a cold start with it like it is it sounds rough.. And you can tell the glow plugs are not doing there job at all... These trucks and these engines are way way too expensive to be abusing mine like that...

The simple and cheap solution is the 70 amp relay like the one I bought. It is nothing more than a 70 amp relay in there now, and GM will sell you one. They charge you roughly $130 for one though whereas you can get them for About $10-15. The rest of the controller is pretty basic and doesn't have to be replaced.

is there a way to test the controller and /or glowplugs if you dont have a obdll tester to get the codes?

So this is the control box correct? and the relays are inside correct?? Is it just the 2 or 3 nuts holding this thing on?? how do you get inside to get to the relay once you get it out?? Thanks so much for all ya'lls help

There are 2 nuts that hold it on I marked with blue. Unplug the connector and remove the 3 large cables that are highlighted in pink. There will also be 2 small wires that you will have to unplug that are down by the 2 cables on the right. Once you get it off you will see a latch that holds the cover on and inside will be 2 relays. The front one under the brown will be the intake heater, and the rear one under the green will be the glow plugs.

alright i'm gonna tear into it this weekend and see what i find lol.!!! Thanks alot for all your help

finally all the answers i've been waiting for...
thanks guys

subscribing, thanks.

Bill.

x2, 12mm/13mm for the controller. 5/16 for the battery cable's.

doing this today couldnt find where it was yesterday or find a relay going to go around today and see if napa or advance auto has it since the closest car quest is 20 min drive.

i don't know if anyone caught it earlier but if going back factory it is cheaper and easier to replace the whole controler not just the relay itself.

Napa also has the relay just got it there part number ar573

Thanks for the part number!!! Just called my buddy at napa and he has it set to the side for me... I think he said it was $13:secret: Hope it fixes her

i just this morning replaced the two relays with those relays from napa but i am still getting a p0380 intake air heater circut A. what do i do next??

i just this morning replaced the two relays with those relays from napa but i am still getting a p0380 intake air heater circut A. what do i do next??

Are you sure that's the code? P0380 is glow plug feedback circuit A. Did you hook up the 2 single wire plugs back up? Do the glow plugs work now? Have you checked the 175 amp fuse over in the underhood fuse box?

p0380 glow plug/heater circuit A is what my code reader says. sorry. i just went back to the shop and double checked. the fuse is good. and how would i check the glow plugs to see if they are working??

Since you said you replaced the 2 relays I'm assuming this is a federal emissions truck. Get you a helper and a test light. With the engine cool or cold, hook up the ground lead of your test light and touch the probe end to the glow plug output post. Have your helper turn the key on and see if you actually have power coming out of it or not. Also listen for the clicking of the relay when you first turn the key on. If you hear clicking but have no power at the post then check to make sure you have power at the large red cable when your doing this. If you have no power at the large red cable then you need to find why your not getting power, if you do have power at the large red post, but not at the glow plug post then the relay isn't transferring the power or you have a broken wire in the controller.

If you have no clicking sound then you need to check the circuits that turn the glow plug relay on. The pink and yellow colored wire in the 4 wire plug is the glow plug relay ground, and the yellow wire is the trigger wire from the ECM. Check to make sure you have a good ground to the relay at the plug. If that is good next you need to see if the ECM request is there. Again with your helper and your test light hooked to ground, check to see if the yellow wire has 12V+ at it when you turn the key on. If you do then the problem lies in your relay or controller wiring, if you don't then you need to check the ECM wiring to the glow plug controller.

If you are still tripping the code, but have power going to the plugs. Then you need to make sure that the light blue wire with the single wire plug is hooked in and has a good connection. the glow plug relay can work, but the code will still be there if the ECM doesn't see voltage on that light blue wire when it commands them on.

you are a life saver! found it! the 175 amp fuse was bad. i pulled it out the first time and thought it looked good but didnt put a test light to it. did what you said with the test light and a friend and traced it all the way back. what a pain. wish i would of done that the first time. thanks for your help and time.

you are a life saver! found it! the 175 amp fuse was bad. i pulled it out the first time and thought it looked good but didnt put a test light to it. did what you said with the test light and a friend and traced it all the way back. what a pain. wish i would of done that the first time. thanks for your help and time.

Those 175amp fuses can test good unless you put a load on them. When they burn out I have seen them carbon arc internally and you will have voltage coming out of it until you put a load on it.

thats what happened i think. he had to cycle the ignition to get the glow plugs to cycle and when they did i would loose power on the other side of the fuse. went into napa got a new one and it works great. no codes.

Are these 175 amp fuses very expensive?

Are these 175 amp fuses very expensive?

I've seen them for under $10 before. The good thing is they rarely blow unless they get shorted out.

So i went to replace my glow plug relay today and my glow plug module is differnt than that in the picture. This is the relay I got from napa http://www.carparts.com/70-AMP-800-WATT-CAPACITY-HEAVY-DUTY-RELAYS/GP_2001332_N__10618.car?zmam=95672150&zmas=17&zmac=100&zmap=10618-2001332 My glow plug module is much smaller than the one in the picture the relay wouldnt fit inside it. I took pictures of my module and the 3 plugs that plug into it. Also of the external relay that I think might be the one I need to replace. I have a 2003 fed emissions truck so that might change stuff a bit with wiring but I wasnt sure. The relay is up under where the intake cover thing is that just sits on top of the motor kind of right in front of the turbo. I attached pictures maybe I was going for the wrong thing but it was right next to the turbo and it said glow plug module on it. http://i484.photobucket.com/albums/rr208/landers11889/2003%20Duramax/IMG_0921.jpg
http://i484.photobucket.com/albums/rr208/landers11889/2003%20Duramax/IMG_0920.jpg
http://i484.photobucket.com/albums/rr208/landers11889/2003%20Duramax/IMG_0919.jpg
http://i484.photobucket.com/albums/rr208/landers11889/2003%20Duramax/IMG_0918.jpg

Easy to replace, 2 beer job with just a couple sockets.


Wow! You either drink fast, work slow or have fumble fingers and dropped one!~;)

Braaap, i wish i could see your pics but since im on the work computer i can not. ill lok at it tonight after work to help ya out.

So i think the worst thing i have had with those relays was the truck would not shut off!. drove down to phoenix one weekend and turn the truck off but it kept runnin! had to pull the main ignition fuse to get it to shut off. after checkin a bunch of stuff i felt the two relays back there and DAMN! they were HOT! so i unplugged it and got a new controller from GM as i was headin on a 1000 mile trip in two days and didnt have time to seach around for the relay. Somehow the constant power side in the relay had melted onto the switched side of the relay and back feeding power keepin the truck runnin. Kinda creepy when your truck wont turn off lol

someone correct me if im wrong but the controler in the last pic is off of a cali truck.

braaap11889 (http://www.dieselplace.com/forum/member.php?u=52970) You have a california emissions controller which means you most likely have a bad glow plug. The CALI controller will trip the P0380 if any of the glow plugs fail, and it monitors each glow plug individually. that single relay you in your pic is for the intake heater. You need to get an ohm meter and go through and check each glow plug seperately and find out which one is bad. I don't know how many miles you have on it, but the CALI emissions glow plug system is covered under an extended warranty due to CARB requirements.

Does anybody have a diagram or exact location of the 175 amp fuse just in case???

Wow! You either drink fast, work slow or have fumble fingers and dropped one!~;)

Hahaha, well I neglected to point out that there IS a 2 beer minimum for any work I do in my garage.
:beerchug:

to get to the fuse you will just have to pull the plastic over off of the fuse box under the hood. i think it is just some snaps that you have to push in and pull it off.

to get to the fuse you will just have to pull the plastic over off of the fuse box under the hood. i think it is just some snaps that you have to push in and pull it off.
but how do i know which one it is?? I don't have a owners manual with my truck so i don't know unless it is marked :D

but how do i know which one it is?? I don't have a owners manual with my truck so i don't know unless it is marked :D

You'll know it when you see it, it's the only fuse inethere like it. It will be held down by 2 bolts(they were 8MM in the fuse panel that I had), and one end will be hooked to the incoming power from the battery and the other end will hook to the large red cable going to the glow plug controller.

braaap11889 (http://www.dieselplace.com/forum/member.php?u=52970) You have a california emissions controller which means you most likely have a bad glow plug. The CALI controller will trip the P0380 if any of the glow plugs fail, and it monitors each glow plug individually. that single relay you in your pic is for the intake heater. You need to get an ohm meter and go through and check each glow plug seperately and find out which one is bad. I don't know how many miles you have on it, but the CALI emissions glow plug system is covered under an extended warranty due to CARB requirements.

I have 90k on it but it's an 03 ao built in 02 about 7years old. But my truck isn't stoc so I might have trouble get it user warrenty even tho the glow plugs have nothing to do with the mods.

I don't have one of those fuses in my truck

Hahaha, well I neglected to point out that there IS a 2 beer minimum for any work I do in my garage.
:beerchug:


Oh!

Must be the "One to get started" and the "celebratory clink" rule, eh?

I think the 175A fuse just fixed my problems. Thanks for the help guys, my old fuse was likely carbon arced.

BTW, 175A fuse at Oreiley's Auto Parts was $5! Thats a pretty cheap fix IMHO.

since i have a cali emissions truck do i have the 175amp fuse?

also will my truck still be under warrenty for the glow plugs at 90k and build date was late 2002

here is a pic of my fuse panel where is the 175a fuse??? is there a different fuse box or somthing or do ihave to go deeper or what??

Go deeper!!! As you face the box from fender it will be under the plastic housing on l/side. You will find 2 tabs sticking through plastic facing engine side. pull out and up on bottom of plastic whole cover pops up. There is a brace I pull off over r/side. You will see!!!

ok got it off.. i'm gonna replace the fuse tomorrow since its cheaper and if that doesn't work i'm gonna replace the relay

Ok so i finally got to work on my truck... I started out with the 175 amp fuse because it was only $4.99 which did not fix it.... Then i tore into the glow plug control box and yes the relay was burnt.. Took it off replaced it and it seems to be workin like new.. Took about 3 miles of driving and the light went off and is still off... But i must say the guy that said this is a quick two beer job must be one hell of a mechanic because it is a pain in the a@@ to get the relay out of the control box...

Ok so i finally got to work on my truck... I started out with the 175 amp fuse because it was only $4.99 which did not fix it.... Then i tore into the glow plug control box and yes the relay was burnt.. Took it off replaced it and it seems to be workin like new.. Took about 3 miles of driving and the light went off and is still off... But i must say the guy that said this is a quick two beer job must be one hell of a mechanic because it is a pain in the a@@ to get the relay out of the control box...

It's a 2 beer job to change the whole controller out, but to do the realy takes some work to get it out of it's holder. I'm cheap though, so I didn't mind the 10 minutes it took me to get the 2 relays swapped out and to have essentially a new controller for a little over $20.

My glow plug light seem,s to work as it is supposed to...after 5 seconds or so it goes off and then turn the key. But...
I have noticed a time or 2 or 3 that when I turn the key the glow plug light stays on for 0.25 seconds or so, then quickly disappears.

What may this indicate?

My glow plug light seem,s to work as it is supposed to...after 5 seconds or so it goes off and then turn the key. But...
I have noticed a time or 2 or 3 that when I turn the key the glow plug light stays on for 0.25 seconds or so, then quickly disappears.

What may this indicate?

Normal operation. The glow plug light is controlled directly by the ECM and works independant of the glow plugs. Mine does the same thing.

It's a 2 beer job to change the whole controller out, but to do the realy takes some work to get it out of it's holder. I'm cheap though, so I didn't mind the 10 minutes it took me to get the 2 relays swapped out and to have essentially a new controller for a little over $20.
I done mine cheaper than that!! I got the one from napa for $12 but then while i had it apart i decided to change out both the relays inside there and napa had already closed so i went up to advanced auto and matched it up to one off the shelf that was $5.99 30amp 12 volt 4 prong.... worked perfect except it has a plastic eyelet on top of it that i had to cut off but it works perfect

I done mine cheaper than that!! I got the one from napa for $12 but then while i had it apart i decided to change out both the relays inside there and napa had already closed so i went up to advanced auto and matched it up to one off the shelf that was $5.99 30amp 12 volt 4 prong.... worked perfect except it has a plastic eyelet on top of it that i had to cut off but it works perfect

If you look you will see that the 30 amp relay has different size terminals on 2 posts. 40+ amp relays have to 1/4" blades and then 2 of them are larger at 3/8". On a 30 amp relay they are all 1/4", and the intake heater draws 35-40 amps and your glowp lugs draw a shade over a 100 amps.

Didnt fix mine, so it looks like I am going inside the controller. :(

knock on wood but my code stopped coming around even at 4* start up.

i have 04 duramax , never had a lick of trouble with anythingon truck 98,500 miles. Last tuesday started truck at work and drove home, parked it, wife leaves for work at 10pm and which time i went to start truck to pull in garage, turned key, no power to anything. Used voltage tester on both batteries, both read 0.0 volts, unhooked both batts and charged slow overnight hoping to trace problem in morning, morning comes hook up both batts crank truck and it starts right up no issue. as i am leaving for work smoke and smell of electrical fire is coming from under hood, scramble to unhook batteries and find that a small plastic relay box, yes the "glow plug" relay box has completely melted down into goo all over my valve cover, hossed it down with my hallon fire ex, to my suprise no wires damaged bought new relay at dealer for 110 bucks , installed and since no issue heard i was lucky not to have had burned up my wires and ecm.. I warning sign i shoulda put 2 and 2 together was that my programer kept reading the code as listed abouve by another guy , was warning me my relay was failing never took the time to look up code thinking it was just a random code.. so if anyone is having a full battery discarge issue please check out your glow plug relay on driver side valvue cover, near firewall. goodluck lol

Ok so i finally got to work on my truck... I started out with the 175 amp fuse because it was only $4.99 which did not fix it.... Then i tore into the glow plug control box and yes the relay was burnt.. Took it off replaced it and it seems to be workin like new.. Took about 3 miles of driving and the light went off and is still off... But i must say the guy that said this is a quick two beer job must be one hell of a mechanic because it is a pain in the a@@ to get the relay out of the control box...

Well, I just swapped in a new control module and didn't monkey around inside the box.

Should the batteries be disconnected before replacing the G.P. Controller?

yes.

I thought so! Thanks Tehbald!

I looked at a truck that was throwing this code, good to know what it was actually doing. Thanks!

I just reseated my plugs and the box and the intake relay (never replaced anything) and knock on wood but I dont have the code and I have started my truck in temps as low as -10 without plugging it in.

My brother just replaced the GPCM in his 2003 LB7 Cali truck, and still gets the P0380 -- 8 months ago, the injectors were replaced and glow plugs and it still threw a P0380. Don't know what to check next.

intake relay, reset the code, reseat plugs

Also check the 175amp fuse

intake relay, reset the code, reseat plugs


Where is the intake relay? and how do you reseat the plugs?

Thanks!

Tried looking for the 175 amp fuse and cant find it... do I have to take off the wheel well liner? I see the 2 bolts that someone mentioned and it looks like they hold something under the fenderwell.

the intake relay should be on the back driver side of the motor right beside the turbo. to reseat the glow plugs you simply loosen the electrical connector, loosen the glow plug itself, and tighten them back up. to get to the 175amp you have to pull the cover off of the fuse box under the hood. just a couple clips as i remember.

So my truck has Fed. Emissions (says the build sheet and my stealership through the VIN #) but, my truck has the same relay and GP controller as Braap11889's pictures in the above post #33. I'm confused!!!??? Can someone explain! I went out and bought the GP Controller for the Fed. Emission truck, opened the hood and imagine my surprise. I changed the 175 amp fuse...that wasn't it.

Relay checked out ok on my brother's LB&, but we still changed it since it was like $7. Have not reseated the glow plugs, but will do it soon. In the meantime, the batteries keep draining, and I noticed on the Predator that there was a Glow Plug Feedback signal of 1.1 - 1.2v at all times -- even after the truck had reached operating temp. We tested that on my LLY, and it showed 0v even at 140ºF ECT.

Where is the intake relay? and how do you reseat the plugs?

Thanks!

My intake relay is right under the 6.6 duramax black cover.

By reseat I mean just unplug them and plug them back in.

the intake relay should be on the back driver side of the motor right beside the turbo. to reseat the glow plugs you simply loosen the electrical connector, loosen the glow plug itself, and tighten them back up. to get to the 175amp you have to pull the cover off of the fuse box under the hood. just a couple clips as i remember.

I don't know what relay is near the turbo but my truck is cali emissions so its a lot different under the hood.

I never changed any relays (well i changed the intake heater one and it did nothing). I also never changed the GPM or the 175amp fuse.

being cali it is very different. and i think it is a little easier to do too but ya know.....

braaap11889 (http://www.dieselplace.com/forum/member.php?u=52970) You have a california emissions controller which means you most likely have a bad glow plug. The CALI controller will trip the P0380 if any of the glow plugs fail, and it monitors each glow plug individually. that single relay you in your pic is for the intake heater. You need to get an ohm meter and go through and check each glow plug seperately and find out which one is bad. I don't know how many miles you have on it, but the CALI emissions glow plug system is covered under an extended warranty due to CARB requirements.

I have the same GP Controller as Braaap11889 in post #33 and my truck is Fed. Emissions. Is that possible. Do they put CA emissions controllers in Fed. Emissions trucks for some reason???

I have the same GP Controller as Braaap11889 in post #33 and my truck is Fed. Emissions. Is that possible. Do they put CA emissions controllers in Fed. Emissions trucks for some reason???

You most likely have a northeast emissions truck. They had most of the cali emissions tuff on them, but didn't set codes for everything like they do. I know on the LLY there is 3 different variations, and I think there was for the LB7 as well.

I have recently developed a hard cold start (if block heater is plugged in truck starts easily) and have been reviewing this discussion. I have confirmed that I have 12.76 volts on both sides of the 175 amp fuse, I have 12.76 volts at the power feed of glow plug controller, I do NOT have voltage on either output of the controller when key is turn on with truck cold.

I have also tried to confirm continuity on the bus bar for the glow plugs to make sure it has not rotted through any where. Placing one of my test leads on the rear output post on the controller and the second lead on the front driver's side glow plug I show continuity. BUT, I also found I had continuity between the output post and ground (valve cover). That can't be correct can it?? If the output post is grounded wouldn't the 175 amp fuse blow?

Any and all help is greatly appreciated.

Update:

I have replaced the two relays in the controller (Federal version) and now that it is all back together I just wanted to confirm the readings I have. I have 12.76 volts at the battery and the positive terminal of the controller with the ignition key off. With the key on engine off and the glow plugs activated the voltage drops to 11.2 volts at the controller positive terminal and 10.75 volts on the glow plug output terminal of the controller.

Can anyone confirm that the controller output voltage is correct at 10.75 volts? That seems like a big voltage drop to me, but this engine is still a bit new to me.

Note for others doing this repair: No one had mentioned in this thread what a pain it is to remove the relay receptacles from inside the controller box. The relays plug into a receptacle that slides into a track and locks in with tabs. The receptacle must slide out in order to remove the relay. You must use a lot of force to push the tab from the under side of the controller box. The tab does not move to unlock as it is not hinged, you simply must force it past the edge that it is locked into. It won't be pretty when you finally get it out.

One other update issue.

Truck is still not starting very well when cold. Only test so far was an over night temp of 26*F and started the truck when it was 35*F outside. Took three cycles of the glow plugs to get it to start without excessively long crank times.

Any thoughts??

had a very similar problem. mine got to the point where it wouldn't start at all unless it was pluged in. then i had my injectors replaced and it was all good.

had a very similar problem. mine got to the point where it wouldn't start at all unless it was pluged in. then i had my injectors replaced and it was all good.


But mine has not been a continuing decline. I had no problems until the glow plug relay went bad (confirmed that it was bad) and now that it is fixed I still have the hard start. So my thought was I still have some kind of a problem with my glow plugs.

i guess i did jump the gun a little bit. what you may want to try next is to pull the bars off and test the plugs alone. if you have a few that arn't working then you have found your problem and maybe even what caused your relay to die in the first place. or since you'll be there anyway, if you have the cash just replace them. there not "that" much.

i guess i did jump the gun a little bit. what you may want to try next is to pull the bars off and test the plugs alone. if you have a few that arn't working then you have found your problem and maybe even what caused your relay to die in the first place. or since you'll be there anyway, if you have the cash just replace them. there not "that" much.


I have been thinking the same thing. I have checked the bars visually and I can't see any issues. One thing that did surprise me was that when doing continuity tests I found that I have continuity from the controller output post to ground. I still can't figure out how that can be right and why the fuse does not blow as soon as the controller brings on the glow plugs.

you will have continuity there but it should be at a high resistance.

you will have continuity there but it should be at a high resistance.


Thanks for confirming that. I did not note the resistance. I'll do that the next chance I get.

I'm getting 2 codes: intake air heater and glow plug circuit A on my dad's LB7 after injector replacement. I didn't have this problem before. Is it possible that I criss-crossed the blue-sleeved wires and/or the thicker black wires (with the protective boot) that attach to the same terminals as the blue sleeved wires?

Does anyone have a diagram of how these wires are supposed to attach to the glow plug module? I have a non-cali emissions truck, with the larger module as shown early in this thread.

Thanks guys and sorry for the slight hijack.

will a bad relay always throw a CEL?

im having some hard starting issues and i think its my relay.

will a bad relay always throw a CEL?

im having some hard starting issues and i think its my relay.


I did not get a CEL when my glow plug relay went bad. Just real hard to start cold. In the process of replacing the relay, while I still had the controller out of the truck, I drove it and then I did get a CEL. I did not bother to check which code was showing.

in my experience a cali truck will almost always show a cel but a fed truck seems like it will almost never show one till it is really bad.

cool. thanks. ill re read he thread and get the Part numbers for the replacement relays. i called gm and the unit was quite spendy.

cool. thanks. ill re read he thread and get the Part numbers for the replacement relays. i called gm and the unit was quite spendy.


Have you confirmed that you do not have voltage at the output post (rear post) on the controller when the engine is cold? I got my relays from CarQuest with part number 56-2335.

cool ill call them. i did call napa with that part # that was listed at the beginning of the thread and they said that relay was the small 1x1x1 square version. if i remember right arn't these ones longer ? or was i just seeing things....

Have you confirmed that you do not have voltage at the output post (rear post) on the controller when the engine is cold? I got my relays from CarQuest with part number 56-2335.


i have not had a chance to check it. i replaced the fuse yesterday hoping it was that. i took the old one apart and it was still good.

all of my tools are not where im currently at. how cold does the motor have to be before i can test it?

i have not had a chance to check it. i replaced the fuse yesterday hoping it was that. i took the old one apart and it was still good.

all of my tools are not where im currently at. how cold does the motor have to be before i can test it?


The relays are about 1x1x1. What ever temp it takes for the dash light to come on when the key is first turned to the on position. I am fairly sure anything below 40*F or maybe even 50*F will call for the glow plugs. Just connect the positive lead of your volt meter to the output post and the negative to a good ground (battery). Prop up your volt meter so you can see it when you reach in to turn the key to on. It is a quick two minute test.

copy that. ill try and test that asap

sorry to hijack the thread but my truck is doing the same thing. Just this winter it started acting like this. I would never have to plug in my truck last year even 10 below it would start good. This year it barely starts at 15 above. The colder it is the harder it is to start. Even when it is about 30 out it misses for awhile after being started and smokes blue for the first mile or so down the road like an old ford diesel. I have a little under 12 volts to the two outputs of the glow plug controller(fed emmisions) when the key is on when cold. I checked all the glow plugs when i did my head gaskets last year and replaced 3 bad ones. Could more have gone south or could i have maybe hooked them up wrong? I looked at the bus bars too and they are not broke anywhere.

Thanks in advance and once again sorry for hijacking but i hate to start a new topic about a similar issue.

ok update. i went and checked the volts. i have 12 volts at the input post of the control box. with key on i have 0 reading at either output post. i can hear a click when the key is cycled on but i did check it multiple times over a few mins and i got no readings.

i took the unit off and tried to remove the relays but could not get them out. i tried to pry in between the relay and where it plugs in but its a no go.

i also noticed someone had injected a lot of white grease all over the electrical plugs where the wires insert. maybe someone has had a problem with moisture before?

so what are my options now. should i replace the entire control module or just the relays??

ok update. i went and checked the volts. i have 12 volts at the input post of the control box. with key on i have 0 reading at either output post. i can hear a click when the key is cycled on but i did check it multiple times over a few mins and i got no readings.

i took the unit off and tried to remove the relays but could not get them out. i tried to pry in between the relay and where it plugs in but its a no go.

i also noticed someone had injected a lot of white grease all over the electrical plugs where the wires insert. maybe someone has had a problem with moisture before?

so what are my options now. should i replace the entire control module or just the relays??

The contacts are bad in the relays or the wiring is defective. To get the sockets out that the relays plug into you have to place a narrow bladed screw driver on the tab that you can see when you turn the controller over and look at the bottom (one tab on each socket). The tab does not compress so you just have to force it past the stop. Not easy but they will go.

Once you have the relays out of the sockets you can then test both the input and output wires to make sure you have continuity. Assuming you do then install the new relays in the sockets and put it all back together.

The grease is there from the factory to keep moisture out. If you don't loose too much while handling it you will be fine. I used dielectric grease on the spades of the new relays.

Good luck.

I was wondering if anyone has replaced the cali emmisions glow plug relay?
How much do they cost?
Are they dealer only?
My dealer is telling me that only the glow plugs themselves are covered on the extended warr. and not the controller, is this true?

Mike

well i got my replacement relay and installed it today. i checked and had about 11volts at both posts exiting the relay with the ignition on.

i started the motor and it fired right up. i watched the volt gauge and the needle sat in between 9 and 14 for about 15 seconds then popped up to about 15.

well i got my replacement relay and installed it today. i checked and had about 11volts at both posts exiting the relay with the ignition on.

i started the motor and it fired right up. i watched the volt gauge and the needle sat in between 9 and 14 for about 15 seconds then popped up to about 15.


Once you figure out how to get the sockets tabs released the rest is easy and it is a great fix for less than $30 as compared to replacing the entire controller.

yeah i decided to just replace the whole thing. i just didnt want to replace the relays and have something else wrong....