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We have a 2017 GMC 3500 Duramax L5P that has been setting a P1029 code. The PCM has been replaced & updated with new software. The fuel pump module has been replaced along with the NOX sensors, (They set a fault code & were just recently replaced under warranty). The throttle body was replaced, also under warranty. All of the wiring has been tested from the computer to terminals, along with the harness grounds have been cleaned & reattached using Dielectric grease. Currently have a fuel pump driver module ordered. Long story/short as we've been chasing this fault code for 2yrs! So far, none of our research has brought up a solution for this code. Has anyone had this situation and found this & what are we missing?

No experience with this particular fault, however I have some thoughts/questions.

Is this a hard fault or intermittent?

What is the freeze frame data when it fails?

3 items suspect for this, the primary fuel pump, the fuel pump control module and the wiring in between the two. Since the module communicates on the LAN, I wouldn't expect the PCM to be a player. I'm sure you already know all of this.

If intermittent, I'd put a scope on those three circuits at each end of the harness and drive it.

GM has always had issues with fretting. Some stabilant on the terminals at the primary pump and FP control module may do the trick.

ricmorin wrote: ↑

Fri Aug 12, 2022 11:37 am

GM has always had issues with fretting. Some stabilant on the terminals.

I found a product called deoxit that is a very good contact cleaner/enhancer. I have used it in both of my work enviroments with great success. Also have a couple friends into audio/video setups and they say it works great for them as well.

I have yet to have stabilant fix any issues.

I use the De oxit here, it is just extra help to make better connection, a little cheaper than the Stabilant.

brianp87 wrote: ↑

Wed Aug 17, 2022 9:17 am

I have yet to have stabilant fix any issues.

The first time I used it was on a 2005 S430 benz. The right front air strut would set a code for bad circuit in the damper valve. after checking and checking I could not find any issue. I was told to try that stuff out on the connector for the strut at the front of the inner fender well by an old guy in Ga. I ordered me some and used the cleaner then the contact enhancer and the problem has not returned. that was about 8 or tears ago and I have had a couple of other issues that were resolved. The most I have used it for was on some BNC type connectors for CCD camera in an x-ray detector head before they went full digital. They were very sensitive to any signal noise and the deoxit helped on some of the tougher issues we had.