Hi all,

New poster here...I've been reading for several weeks now, and before anything else, thanks to all for a great resource. I just bought my truck in early February, and with the help of the forum I've successfully diagnosed a bad wastegate solenoid -- replaced; a non-functional lift pump -- broken wire repaired; and generally learned a lot about my truck.

Now to my problem: I found a coupon last week for a free diagnostic check at a diesel shop in Denver, and decided it couldn't hurt to go get the truck checked out. They spent two hours, and found several minor things, some of which were news to me, and others that I already knew about. However, when I started the truck to leave, the SES light stayed on!

I was short on time, so I couldn't turn around and go back to the shop right then. However, later in the afternoon, I read the codes; it's flashing 56, and nothing else -- it *doesn't* start by flashing 12, and never seems to stop flashing the 56.

I've checked the codes before and had none, and when I tried to clear this code, it had no effect. The report from the shop also says, "Scanned truck & found no codes & datastream looks ok..."; but when I called them back, they claimed that their report showed injector pump problems, and that it *couldn't* have been due to anything they did.

So have I been had? Should I go back and pound on someone's desk until they correct it? Or should I just fix it myself, and count it a lesson learned?

Thanks,
sje

Methinks your PMD is missing the resistor that should be inside it....have a look....

Chris,

Thanks for the quick response. I did look earlier, and didn't see any sign of it -- it should be obvious if I pull the plug out of the PMD, shouldn't it?

If it's on the Injection pump and not on a relocated heat sync, you won't be able to see it, maybe you could with a little mirror on a stick. it should be inside the female jack on the PMD. but if you can see in there then yes it's pretty obvious, and it will have a little number in the bottom right corner telling you if it is either a 1-9 resistor, 9 being more fuel, 1 being less.(in lamens terms. I'm know it's a little more indepth than that, you can check out kennedy diesel or SSdiesel for a better description on the resistor.)

This has been a little sticky point in the past in relation to ECM resistor polling rate. It could be that if the resistor was missing/never installed, it stored the last resistor value. They went to scan the ECM, or pulled battery power, it cleared the resistor stored value.

If the resistor is not present, it really isn't their fault (unless they took it - highly unlikely, but then again....) they just uncovered a problem that was there when you drove in.

Just a theory...

ya i kinda agree, was this a reputable shop because it wouoldn't be a bad scam now that i think about it, to give out a free scan and then just create new problems and tell people who don't have a scanner about them and then say that they can fix them. But i am one of those conspiracy thery kinda guys lol:D

The resistor should be obvious...it is a little chip with a small resistor across two pins...

Well, I took another look -- with a flashlight -- just to be sure, and there's definitely no resistor in there. So now we have three possibilities: deliberate malfeasance by the shop -- pulled it out to make me come back and pay them to fix it; carelessness by the shop -- pulled the plug and the resistor fell out, and they didn't notice; or knkreb's theory that it's been missing for a while, and I've been running on a stored code.

The shop did appear to be on the up-and-up -- it's a big operation, with three locations, their own parts house in the same building, etc. -- with the exception of the claim that their report indicated IP problems, when it didn't. That makes me think there's at least a possibility that knkreb has it right, and if that's the case, I don't want go back and demand they replace a resistor that was never there -- so for 10 bucks I'll probably just go buy one.

That leads to one final question: once I get a new resistor and install it, will the ECM just recognize it, since it seems to be unhappy with the current situation? Or do I have to do something to tell it to go and look?

Thanks again for all the help! :o:

Hmm, am I looking the right place?

I have my engine out right now (putting in a rebuild) and have heard people talk about this resistor before, so I decided to have a look. I don't find one there either! I wasn't showing any relevant codes before pulling the engine out (and I cleared the codes during my diagnosis, so I don't think it would have remained unset from sometime past...)

Please see the following pictures:

http://img.photobucket.com/albums/v719/derekja/truck/DSC00383.jpg

http://img.photobucket.com/albums/v719/derekja/truck/DSC00381.jpg

Hmm, am I looking the right place?

I have my engine out right now (putting in a rebuild) and have heard people talk about this resistor before, so I decided to have a look. I don't find one there either! I wasn't showing any relevant codes before pulling the engine out (and I cleared the codes during my diagnosis, so I don't think it would have remained unset from sometime past...)

Please see the following pictures:

http://img.photobucket.com/albums/v719/derekja/truck/DSC00383.jpg

http://img.photobucket.com/albums/v719/derekja/truck/DSC00381.jpg

Derek,

From your pictures, that looks like the right place to me. I've been going by the pics at ssdiesel:

http://www.ssdieselsupply.com/product_3_6.5_Diesel_OEM_Calibration_Resistor.html

Oh, and I guess a new one is 20 bucks, not 10. :rolleyes:

hmm, interesting. Well, I'm tempted to throw one in there, but since it wasn't putting up any codes I guess it's not really necessary. I have an updated PCM which should do more for fuel delivery than the resistor would, I think.

Strange.. wonder what happened to it!

hmm, interesting. Well, I'm tempted to throw one in there, but since it wasn't putting up any codes I guess it's not really necessary. I have an updated PCM which should do more for fuel delivery than the resistor would, I think.

Strange.. wonder what happened to it!


Derekja - IIRC, if your OBD-II re-polls and figures out you don't have one, your truck won't run. The OBD-I trucks would default to lowest value, but the OBD-II guys just quit.

At least, that's what I remember from what the gurus said when we were discussing the potential of the infamous 'fuel controller', which supposedly simulates several different resistors.

The OBD-I should re-poll every 50th starrt or so, or with a commanded tdc learn, but the OBD-II shouldn't re-poll unles either commanded to do so, or unless batteries are disconnected for a few minutes.

Any of you experts have more or contradictory information to add to this?

For the OBD I system you should be able to disconnect the batteries for a few minutes and get a new TDC learn when you hook everything back up....remember - the GPs may or may not light on the first start up...if they don't light right away just turn the ignition back off and wait a few more minutes....on the next attempt to start the truck you will get the desired glow time...

oh, interesting! Thanks, Jifaire. I guess I will worry about it now, then, since from looking at other posts the TDC re-learn I'll have to do to get my timing correct will cause it to re-poll the resistor value.

That's really very curious. I didn't have that plug off until just this afternoon when I went to look for the resistor, and to my knowledge that's the first time in 215,000 miles that that IP has ever been messed with. At least none of the service records on the truck indicate anything different.

Nah ... can't be. If the PMD is on the IP after that many miles without being replaced, I'll eat Chris' hat.

Somebody replaced the PMD and just forgot to move the resistor over to the new one would be my guess.

The fact that nothing else has been done would explain why your original value is still stored.

Nah ... can't be. If the PMD is on the IP after that many miles without being replaced, I'll eat Chris' hat.



lol...

I'll give you my work hat....lightly seasoned with diesel and grease...:D