'05 Duramax intermittent P2139 P2140

My 1st post so any feedback is appreciated
'05 Chevy Silverado Duramax LLY diesel motor 200k miles

Intermittent, about once a year since 2012 accelerator goes to idle only, chime and reduced power display, shut truck off, 1 to 3 start cycles accelerator returns to normal. This happens on smooth and rough roads, with engine cold and at normal operating temperature. Twice it's gone to idle-only 3 times in less than an hour, the other times it goes to idle-only just once. In either case it's about a year before it comes up again. My Autoenginuity shows codes --

P2139 The APP sensor 2 and the APP sensor 3 are more than 10 percent out of range of each other
P2140 The APP sensor 1 and the APP sensor 3 are more than 10 percent out of range of each other

P1125 ECM detects condition with more than one sensor never sets.
So seems problem is with sensor 3?

I've also had intermittent codes for VPS P2565, CKP P0335, and Cruise Control, no codes just inop cruise control. I made long-term fixes for these problems by replacing the ECM connector pins for these sensors with pins from a like salvage-yard connector -- spliced salvage yard pin and pigtail with solder and shrink tube into ECM connector. I made these repairs after spotting 1 of the VPS pins in the ECM connector looked enlarged and I closed it up a little with a small pick and that fixed it. I've twice replaced the 9 pins for the APPS and the problem persists.

I have 2 accelerator assemblies and 2 ECMs and the DTCs have come up with both of them. The ECMs have been tuned by duramaxtuner.com. However, I got these codes with 1 of the ECMs before it was tuned.

Back in my garage I've never been able to duplicate the problem. I've never had my Autoenginuity hooked up when the DTCs were current. KOEO I wiggle the 3 connectors and wiring between the pedal and the ECM and listen for the chime to tell me the codes have set. I disconnect and reconnect the 3 connectors key off, go back to KOEO and have never duplicated the problem. Visual inspection of the connectors shows no pushed-back pins or other problems. The wiring harness for the pedal is a separate harness from the pedal to it's own firewall grommet and on to within a foot or so of the ECM before it merges with the large wiring bundle to the 3 ECM connectors. So it's easy to inspect up to the point it merges with all the ECM connector wiring.

Autoenginuity shows the 3 APPS in range for 0% and 100% pedal and the 3 5 volt reference signals stay right at 5 volts each time I've looked at them with the truck running and also with the key in run, engine off. I have alldata and it only shows values for the 3 APPS at 0 and 100% and says the voltage should change smoothly as the pedal is depressed which it does. I've logged APPS signal volts, pedal percentage, and 5 volt references while I drive and see nothing that gets my attention. Since I've not been able to duplicate the problem and because Autoenginuity shows no signal or 5 volt reference problems I've not checked anything with my DMM or test light, just visual inspection, wiggle test, and what the scanner shows when pedal operation is normal. The truck is a southwest truck (Tucson) so there's very little to no corrosion on electrical connectors.

Any response is appreciated.

Ahh yes diagnosing intermittent conditions can be very difficult it looks like the problem lies with app3 as 1 and 2 are both not matching it it sounds like you have covered your basics with checking connector pins and wiggle wire testing , I see you have tried a 2nd accelerator pedal assembly? Was it new or used ? If new what brand? When it did act up what were the other electrical loads on the truck? Sometimes if you have a bad ground wire this can cause issues like this if your pulling more load then a corroded connector can carry for example headlights might have a ground that attaches to inner fender or core support and make no difference to any load in cab but something like radio or rear defrost or trailer brakes may be hooked to cab ground and under certain instances cause electric load problems. However I should mention every time I've had app correlation codes it's been a faulty accelerator pedal but I still verify wiring integrity first.


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Thanks for the post--I agree the problem is with APPS 3.

1 pedal is the original stock the other a new Airtex/Wells.

Electrical loads were mostly light when the DTCs set--in town, daylight, no AC, and no trailer. Once set the DTCs 3 times on a 5 mile 6% hill climb.

I've got 2 Ford Taurus electric fans for radiator cooling, but see no correlation between fans and DTCs.

Maybe I'll buy a new GM pedal just to help eliminate pedal as problem.

You could try using data logging on all the time while your driving to see what happens to signal and 5v reference when the problem occurs, wells is a decent brand it's hard 2 believe that app3 would be intermittent on both pedals(the odds are probably better at winning lottery.. i don't think I'd be to quick to run out and buy a 3rd pedal if the 2nd pedal were used id be skeptical of it .

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Good inputs, thanks.

I can log the 3 sensor voltages, pedal % 0-100, and the 3 5 volt references that are used by lots of sensors in the truck--oil pressure, EGR, fuel pressure, CMP, boost, Baro, VPS, A/C . I'll get more diligent about logging, hopefully see what's up when the DTCs set. I like your lottery odds input so I'll keep thinking/working on diagnosing it.

I'm leaving my laptop in the truck connected to the diagnostic port and logging any time I drive the truck.

So, if I manage to set P2139 P2140 (1 and 2 >10% out of range with 3) while data logging the 3 APPS with Autoenginuity what am I looking for to help me find the problem?

My scanner will show 3 signal voltages, 0-100% pedal, and 3 5-volt reference voltages that are used by the APPS and lots of other sensors--CMP, EGR, Baro, ...... 5-volt reference 3 is used only by the CMP and APPS3. I point this out since it seems APPS3 is the sensor that gets out of range and sets the DTCs.

Are there other PIDs I should log?

I have Alldata and it shows a signal volts range for 0 and 100% pedal. APPS3 at 0% pedal is 3.95-4.13, 100% 2.69-3.16 volts. So if I set DTCs and the log shows APPS3 at 0% and 3.55 volts and that's 10% out of range with 1 and 2 what do I do with this info to find my problem. I don't see how to determine that I'm seeing >10% difference accept that the ECM says it is!

I have wiggle and visual checked wires and connectors many times to no avail. The DTCs are fleeting, they come up about once a year, then it takes a key cycle or two to clear them. Any thoughts on how I can do a better check of the 3 APPS wires and their 3 connectors when the DTCs aren't set.

Hey now thats good informatiom to have that app3 shares 5volt ref with cmp! Log all your apps and all your 5 volts and your cmp as well as any other sensor that is on any of those shared 5v lines . A faulty sensor category your 5v ref and cause app 3 to read low causing it to be over 10% out from the other 2 and those are way better odds than winning the lottery!

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Yep, sounds good, I'll add in the other sensors that use 5 volt reference.

I'll add that I've never had DTCs for 5 volt references, high or low. My truck will set codes for each of the 3 5-volt references. But maybe they were not off enough to set DTCs.