Engine/Transmission (1998.5 - 2002) Hard Start

[PSoffe]

I did a little research in the forums this morning and I am trying to make heads or tails of this hard start problem that I am experiencing.



A couple of weeks back we experienced a 1689 and replaced the VP based on information from my mechanic ( a reputable diesel shop). Having done that we left on vacation only to have it throw the same code during the trip. Truck ran fine but every once in a while would hard start, more so when it was warm but not always. Called my mechanic from the road he said drive it and when you get back bring it in.



We returned home just fine (it didn't leave us stranded) but still had the intermitent hard start.



The shop went through all of the wiring harness (checking communication) between VP and ECM all looks fine. Sent VP back to manufacture as they said it was a defective pump. New replacement installed and still have the hard start problem, no codes.



We installed the FASS95 just over a year ago and have never had a problem with starting, fuel pressure is a constant 17psi, 14-15 WOT.



I am baffled. I know that there have been issue with weak diaphrams on the VP and the addition of the FASS but that problem should have been present almost right after install prompting the mod for the delayed pump start that is in there (FASS) instructions.



Someone said that Smarty had a line of code in there programmer that is left behind that delays the LP on start up. Is this a possible fix?



Truck down two weeks now. HELP! Shop is doing everything they can and doing it under warranty. Just confused.

 

[JLandry]

Pat,



In an older post, you said your truck had a P1698 trouble code. Your current post says it has a P1689 code (note last two digits swapped). I'm curious if one of these is a typo? Knowing the correct code will help nail down the problem.



In either case, these trouble codes indicate a communication problem on the CAN bus. The problem could be with the CAN bus itself, with the PCM (a failure), or with the ECM (a failure).



Assuming the repair shop has eliminated a communication problem with the wiring harness or connectors, then these codes point to either the PCM or ECM having a problem. It's not a fuel injection pump problem as the replacement has proven.



I believe I read in an old post of yours that you replaced the ECM... is that correct? If so, did you install a new, rebuilt, or plain used unit? Where did it come from? I ask because with the symptoms you're describing, my vote is that either the ECM or PCM (depending on which trouble code you really have) has an intermittent internal fault.



In the mean time, one long-shot thing to try...



Swap the ASD relay found in the PDC (Power Dist. Center) on the driver's fender under the hood with another non-essential relay (such as the wiper relay) and see if that cures the hard-start problem. A faulty ASD relay will allow the truck to crank, but will prevent the PCM and ECM from sending run commands to the VP44 fuel injection pump.



Best regards,



John L.

 

[PSoffe]

John,



It was a P1698 (typo) Communication error. I did have ECM replaced by Dodge with a new unit. As luck would have it the 1 year warranty ran out 30 days ago. So hopefully it is not another ECM.

 

[JLandry]

It was a P1698 (typo) Communication error.

Pat,



A P1698 code means there's either something wrong with CAN bus communications in the wiring harness between the ECM and the PCM, or the PCM (not the ECM) has a problem.



A Chrysler DRBIII Scan Tool is normally used to troubleshoot CAN bus communications problems in the wiring harness, and if those tests turn up negative, then the PCM is replaced. A Dodge dealer would have a DRBIII or they can be purchased used on eBay for $2800 and up.



Has the repair shop you're using cleaned the PCM connectors and verified the PCM body is well grounded? I ask because I wonder if they've been focusing only on the VP44 Injection Pump and the ECM.



You can buy a refurbished PCM from Auto Computer Exchange for $299. I and others here on the TDR forum have had a good experiences buying from them.



My thought is it might be worth swapping out the PCM to see if it cures the problem (after you first try that ASD relay swap I mentioned). If swapping out the PCM doesn't fix the problem, you can either keep the PCM as a spare or resell it on eBay to recoup most of your investment.



Please keep us posted on how everything works out.



Good luck,



John L.

 

[PSoffe]

John,



Thanks so much for all of the info. I am hoping to get some kind of update from the shop today. I will gently pass along the info so as not to bruise any egos and see if they have looked into this area deep enough.



I will keep you posted and thanks for all the help.



If something new arises I will post it right away.



Pat