OBD-I High Idle Setup Guide
For use on 1994-1995 6.5L Trucks
(For 1996+ OBDII Trucks Click Here (http://www.dieselplace.com/forum/showthread.php?t=230913))


This mod will come in handy for faster warm-ups in cold weather and if you idle your vehicle a lot. People say if a Diesel engine idles for long periods of time under 1,000 rpm it could possibly wash down the cylinder walls. The high idle will raise rpms to approximately 1100 rpms.

Parts Needed:
Computer Pin Terminals [OEM #12089649]
Approximately 16ga wire or bigger and connectors [$5 for a small spool]
Add a Wire Fuse Tap [$7 - Advance Auto - 5080114 (BP/HHH) ]
Rocker or Toggle Switch [$5-10 part store]Step 1:
Remove Dash Bezel
You can remove the dash bezel by dropping steering column as low as it will go, putting gear shifter in 1st (on automatics), and pulling the cup holder out a little bit. After that pull at a corner and pull all the way around the bezel. The only thing that holds the bezel on are the clips.
Once all the clips are lose you can unplug the headlight switch, cargo switch, and 4x4 switch (if equipped).

http://www.dieselplace.com/forum/attachment.php?attachmentid=94419&d=1258946040
http://www.dieselplace.com/forum/attachment.php?attachmentid=94418&d=1258945881

Step 2:
Getting to the Computer
Open up your glovebox and empty it out. Once that is done, push in the tab on each side (see picture). After the top is loose, drop the box a little bit more and pull out. You will now see the computer on the right side.

http://www.dieselplace.com/forum/attachment.php?attachmentid=94425&stc=1&d=1258948116
http://www.dieselplace.com/forum/attachment.php?attachmentid=94421&stc=1&d=1258948116

Step 3:
Installing Switch
Chose a place to install your switch (see pictures for mine). Be careful when you drill your hole for the switch. Its basically a one shot deal, because if you mess it up its going to be there and you can't really hide it.
After the hole is made, install the switch in your dash.

http://www.dieselplace.com/forum/attachment.php?attachmentid=94426&stc=1&d=1258948116

Step 4:
Wiring the Switch
Using the fuse tap kit, plug into a fuse that only has power when the key is on (I used the radio fuse for this) and run the wire to the switch. Next you will want to take enough wire to run from the switch to the computer with a little slack (see picture where i routed mine). Connect wire to switch and run along inside the dash and to the computer behind the glovebox.

http://www.dieselplace.com/forum/attachment.php?attachmentid=94422&stc=1&d=1258948116
http://www.dieselplace.com/forum/attachment.php?attachmentid=94427&stc=1&d=1258948116

Note: When using a switch that has a light in it, if you want the switch to light when in use you will have to ground the switch as well.

Step 5:
Connecting to Computer
Once you have ran the wire to the computer, strip the end of the wire and connect the terminal pin for the computer. Next, remove the center pink 24pin connector by squeezing the lock tabs and pulling.

Remove the lock on Row A on the top part of the connector. Place the wire with the terminal pin into slot A6. After you complete that remember to put the pin lock back in place and then connect the connector back into the computer.

http://www.dieselplace.com/forum/attachment.php?attachmentid=94423&stc=1&d=1258948116

Step 6:
Finishing Up
Once you think you have everything hooked up how you think it should be. Place your dash bezel up where it should go and connect the wires (including your new high idle switch). Start your truck and test the high idle. If it works, then go ahead and clip your bezel back into the dash and install your glovebox. If it doesn't work you will need to make sure all your connections are good and that you are getting 12v to the switch and with the switch on you are getting 12v to the pin terminal.

Some more Pictures:
http://www.dieselplace.com/forum/attachment.php?attachmentid=94424&stc=1&d=1258948455
http://www.dieselplace.com/forum/attachment.php?attachmentid=94428&stc=1&d=1258948455


Note: Always be careful when probing any wires going to or from the computer!
Note: From what I know, OBDI trucks do not shut off High Idle when brake is depressed or truck is in gear.

I know the dash is different on a '94, is the computer plug still the same?

I know the dash is different on a '94, is the computer plug still the same?

Yes, the computer plugs/connectors are the same.

Good write up, It is pretty much the same for the 94's just diff dash setup.

You Are right, the high idle does not disengage when the brake is pressed or put into gear.

woohoo Thank you! more goodies to put on the dash :D:D:D

Great write-up Mike, bought time we had one for the OBD-I guys!!

Bout time we have a OBD1 high idle how to :D:p:

Good job Mikey.

Edit: Great minds thinking alike Matt? Lol

Great minds thinking alike Matt? Lol

Yes they do!!! It's almost like having ESP!?!?!:bigglasse

hello this might be a stupid question but will this work on a 93 it has the mechanical ip and if no is there a way to do it on it

thanks green i was waitting for some to put that on here know i can get my done

hello this might be a stupid question but will this work on a 93 it has the mechanical ip and if no is there a way to do it on it

This will not work on '93 trucks. Not sure if there is a way to do it either.

If the '93 is anything like my '86 you can... just put 12v to the plunger solinoid on the IP that is used for cold starts. I'm not sure what it's called. :(

Bill

Green Machine, what do you mean by wash down the cylinders if you let the truck idle for a while. I know people who just let them run for a while and this seems to be the norm, expecially for warmup. Thanks.

Jim

Green Machine, what do you mean by wash down the cylinders if you let the truck idle for a while. I know people who just let them run for a while and this seems to be the norm, expecially for warmup. Thanks.

Jim

I'm talking about letting the truck idle for hours at a time. Most warmup periods during the winter for our trucks should be 3-10 minutes. I let mine sit and run for 3-5 on really cold days. down to about 35 i let sit only for a couple minutes and drive easily through town and by the time i get out of town its up to about 180.

can a high idle be done on a 92?

i have a 95, and i have wanted to do this for a while, do i have to run to the fuse box? or can i just splice into it from one of my radio power wires near the deck? i got enough wires in the fuse area from a previous owner, and i dont like that method just wondering if i can do that instead. Also i dont know where to get the pins for the computer, is there an alternative way of splicing into that too? or is this generally the only way?

I got my pins at the "recycled parts store". I cut a plug with wires from a parted out truck. I still have 10 or 15 left. If you PM me I could send you one for free.

i have a 95, and i have wanted to do this for a while, do i have to run to the fuse box? or can i just splice into it from one of my radio power wires near the deck? i got enough wires in the fuse area from a previous owner, and i dont like that method just wondering if i can do that instead. Also i dont know where to get the pins for the computer, is there an alternative way of splicing into that too? or is this generally the only way?
You don't "have" to run to the fuse box. But like any manufacturer they don't "recommend" splicing into other wires. But if you splice into the radio wire, just add a fuse the high idle wire for extra protection ;). From what I know you have to use the pins for the PCM so you get a good connection at the computer.

You don't "have" to run to the fuse box. But like any manufacturer they don't "recommend" splicing into other wires. But if you splice into the radio wire, just add a fuse the high idle wire for extra protection ;). From what I know you have to use the pins for the PCM so you get a good connection at the computer.

alright yeah, its always good to put fuses in, i have two radio harnesses ( one for old alpine deck and one for my new deck, works fine) and i got two fuses in there so i can tie into of of them, will work alright i think, and i am gonna try and get those pins then. Thanks for the help everyone though! this is a great forum on these trucks! Very impressed!

Thanks for the How to pictorial with pictures...it made the job that much faster for me to do. I did it on my 95 and it works great!!
Only thing is that it doesnt kick down the idle when pushing on the break pedal and/or putting it into gear....I can live with that.

Thanks for the How to pictorial with pictures...it made the job that much faster for me to do. I did it on my 95 and it works great!!
Only thing is that it doesnt kick down the idle when pushing on the break pedal and/or putting it into gear....I can live with that.
Yeah, most (if not all) OBD-I trucks will not kick down when depressing brake or putting into gear. I think most OBD-II (96+) will, but now ours :(.

Nvm dumb question, i re read it a few times and figured it out, so the A6 wire stays out after connecting it all together correct?

Nvm dumb question, i re read it a few times and figured it out, so the A6 wire stays out after connecting it all together correct?


Your adding the A6 wire (12 volts switched) and that goes to the switch....the a6 Slot is empty untill you add it.

Did you use a special tool to crimp on the terminal end at the PCM or just a crimper tool/pliers?

Thanks

I just used pliers lol

Dave (or anyone else, for that matter), do you know if the ODB-I rigs can have a 1600 RPM high idle, similar to the ODB-II rigs, too?

I did this mod a while ago, and my tuck idles at 1400 instead of 1100 I'm not sure why but I guess I can live with it maybe just my computer is special lol

I'm fine with an 1100 RPM idle. But I thought that the ODB-II rigs could have a fast idle for something like 1000 RPM, 1300 RPM and 1600 RPM or some such.

I'd have to re-read the mod to find out.

:woohoo:Great thread. I have had the high idle hooked up to my temp sending unit and it raises it but would rather have it like this. Will this throw the service engine code as it is now it does for me since it is just grounding out the sensor.

orionthade obd1 doesnt have different idle options



rbtaylor14 I get no codes with the switch installed to the computer

I'm fine with an 1100 RPM idle. But I thought that the ODB-II rigs could have a fast idle for something like 1000 RPM, 1300 RPM and 1600 RPM or some such.

I'd have to re-read the mod to find out.

No, you can't do that with OBD-I. OBD-II does it through two different switches. OBD-I has one switch and high idle is wherever it's set on the chip.

where did you get the GM pin for the PCM???

where did you get the GM pin for the PCM???

I bought a pack of 10 from amazon. Have 9 left over. Send me a private msg with your name and mailing address and I'll send a couple to you

Ryan

If you look at the first post it has the part # to get from GM
Computer Pin Terminals [OEM #12089649]

I think I paid 1.25 for one

ya where did i get them all the parts stores dont have them

At the Chevy Dealer...

Works good in the winter and in the summer. AC on max with the engine running at high idle cools down quick.

got them from NAPA GM terminal 725180 that is the napa part number for the terminal

thanks guys

so it is just sending 12v straight to the ecm pin correct?

so it is just sending 12v straight to the ecm pin correct?
Yes, but it should be fused and have a switch to cut power ;)

yeah just makin sure i dont need any resistors

Doing this ASAP..... I run my truck for over 30 minutes in the mornings and it STILL aint moving the temp gauge!! AND I sit in it at lunch time for 30 minutes but only AFTER a have let it run for 30 minutes to warm up first :eek:

I HATE the winter!!

only good way to warm her up is to drive her !!!!

Did it and it works fine. Even MORE noise for the neighbors to get up to in the mornings. :)

hooked mine up today works good. what happens if i would leave it turned on while driving with the manual trans? it will just stay at the high idle when you let off right? it wont hurt anything will it?

hooked mine up today works good. what happens if i would leave it turned on while driving with the manual trans? it will just stay at the high idle when you let off right? it wont hurt anything will it?
All OBDI trucks i've seen with this mod done doesn't shut off high idle when brake is depressed or truck is in gear, unlike some OBDII trucks.

It will stay in high idle mod even after you go in gear (if it is anything like the other trucks i've seen). I'm not promising anything, but it shouldn't hurt anything... computer wise anyways. With you it shouldn't matter leaving it on, but why would you want it to stay one? (NOTE: Those with automatics make sure you shut the high idle off ;) ).

thanks, just wanted to know in case i forget to flip it off before i put it in gear

thanks, just wanted to know in case i forget to flip it off before i put it in gear

I managed to get this one right the first time and it works just fine.

hey green machine im doing the high idle mod on my 95 chevy 4x4 6.5 turbo vin S im all rigged up but i dont know wich pink wire u saying. center 24 pin?? they are 3 pink wires 1 in each connector in your picture u have the plug out is it the solid pink wire at the end on row a
??? thanks. good write up very detailed info...

I don't think he was talking about a pink wire, but the center computer terminal block connector being pink, and inserting the pin into terminal A6.

Steve

hey green machine im doing the high idle mod on my 95 chevy 4x4 6.5 turbo vin S im all rigged up but i dont know wich pink wire u saying. center 24 pin?? they are 3 pink wires 1 in each connector in your picture u have the plug out is it the solid pink wire at the end on row a
??? thanks. good write up very detailed info...

I don't think he was talking about a pink wire, but the center computer terminal block connector being pink, and inserting the pin into terminal A6.

Steve
What Steve said. The pink connector that plugs into the computer. What you want to do is place the wire from your switch into the A6 slot of that connector. There shouldn't be a wire located in that slot if that helps at all.

Good morning all,
I was wondering if it is possible to install a "2 Way" setup on an OBD 1??????
Could a guy use a 2-Way rocker switch, so I have a choice between 1050 RPM and 1300RPM? (or whatever speeds are available in the PCM?)
I would like to have the choice of about 1050 RPM, as well as 1300 or 1600 RPM....
sometimes I need more heat in the cold, and sometimes I need to leave it run without "roaring" waking up the neigghbors, etc.
What pin slot equals what speed? and how would I do a 2-Way or even a 3-Way high idle speed setup on my OBD 1 1995 setup? Thanks

What Steve said. The pink connector that plugs into the computer. What you want to do is place the wire from your switch into the A6 slot of that connector. There shouldn't be a wire located in that slot if that helps at all.

Oh, the center block. I was a bit confused about that as well.

hey steve 53/green machine i gott it figured high idle works great thanks are they any other mods to do to the computer and engine

I'm trying to install the switch but in the "A6" slot their is already a yellow wire in it. My computer only has 2 plugs and its for a 92 2500 6.5td. Where should I put the pin for the mod?

1992 will have a mechanical DB2 injection pump. This mod will only work on 1994+ with an electronic DS4 injection pump.

Ok, is their anyway to install a high idle switch?

It's not as simple as a switch. It's all mechanical. You can try searching or looking in the 6.2 forum. There might be some suggestions there.

Where do i get the pin connecter for the computer will i be able to get it from advanced and will it be under the part number listed

Where do i get the pin connecter for the computer will i be able to get it from advanced and will it be under the part number listed





http://www.dieselplace.com/forum/showpost.php?p=4118480&postcount=34

I bought a pack of 10, I have 9 left over. If you pm me your address I can mail you a few

Ryan
Where do i get the pin connecter for the computer will i be able to get it from advanced and will it be under the part number listed

Ryan i send you a pm let me know if you got it thanks

I will be doing the high idle with a twist. I just bought a remote starter that with a push of a button the rear defrost will turn on. So that will be my high idle. The trunk button will be to roll up the Windows. I did the window for my last remotely starter.

do i need to unhook the battery to do the high idle mod thanks and the connector i need to remove is the middle one right

do i need to unhook the battery to do the high idle mod thanks and the connector i need to remove is the middle one right
It is alway a good Idea to unhook the battery whenever you do any work with the computer

Or just unplug computer before you insert the pin.

I just did the mod today. Its awsome, when ever i am idling for awhile i turn it on, cant wait to see how it helps tomorrow morning, its going to be around 25 f.

can someone post a picture of the pin connectors? I pulled an ecm connector from the junkyard, want to make sure it is the same, thanks