reduced engine power 2yrs allmost ready to sell

[mkcom1]

okay so here goes:

2005 silverado 1500 hd, 6.0 135k. Codes p2135 throttle pedal position sensor switch a/b voltage corelation, p0300 random multiple cylinder missfire detected, p0120 throttle pedal position/switch a circut. I have been fighting this isuue for the last two years and it is getting to the point I am ready to sell. I hate to do that as the truck is in overall great shape, well maintained with no other mechanical issues. As I said this issue has been going on for at least two years with some limited success for intermittent times at a resolution. I have replaced at different times all of the following all with oem ac delco parts. some of these were done due to other codes etc. throttle body, pedal postion assembly, wiring harness to the throttle body with new wires allmost going to the ecm ( did strip the old harness/plug and did come across a bad wire), the ecm, fuel injectors, cats, all 4 o2 sensors, map, mass air flow, knock seensors, plugs wires , intake gaskets, fuel pump and fill sensor, alternator, battery, I have also ran a new wire for the two grounds at the back of the block direct to ground. Currently after the ecm was replaced last, about 3 weeks ago, i have been getting this problem only upon start up at different times, hot or cold about 12 times a week. It always resets after I shut it down and wait a minute or two and I haven't had to erase the code to get it to go away. My next step short of selling the truck would be to replace the whole engine harness as I feel this must be a wire problem and trying to find that might take longer than a new harness install. I am in the Chicago area and If anyone has a reputable shop that has dealt with something like this I''d be interested in there name. Ant other reccommendations would be greatly appreciated. thank you

[Swimmer8366]

So what exactly is it doing just miss firing?

 

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[mkcom1]

well no, I do get a missfire random code but not every time. on start up it goes into reduced power with the two mentioned codes. This has happened without even starting the engine, just in the run position.

[Swimmer8366]

And it's not constant? You said you replaced harness ggoing to pedal?

 

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[Swimmer8366]

This is a shot in the dark but have you played with the fuse box yet? I would check the wiring in the bottom of there. Again at random shot in the dark.

 

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Have you been to dealer? To check for TSB?

 

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[Swimmer8366]

 

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[Swimmer8366]

Check your pig tail on the throttle body and do and relearn and let us know what you find.

 

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[mkcom1]

not constant meaning at every start up but like I said about a dozen times per week. no not the pedal harness just the tb harness. And yes I know about the TSB and it relates to shorts in the harness at the TB. It has not been to the dealer, I'd be broke at this point. Ecm has been replaced n flashed as has a crank relearn done.

not constant meaning at every start up but like I said about a dozen times per week. no not the pedal harness just the tb harness. And yes I know about the TSB and it relates to shorts in the harness at the TB. It has not been to the dealer, I'd be broke at this point. Ecm has been replaced n flashed as has a crank relearn done.

not constant meaning at every start up but like I said about a dozen times per week. no not the pedal harness just the tb harness. And yes I know about the TSB and it relates to shorts in the harness at the TB. It has not been to the dealer, I'd be broke at this point. Ecm has been replaced n flashed as has a crank relearn done.

not constant meaning at every start up but like I said about a dozen times per week. no not the pedal harness just the tb harness. And yes I know about the TSB and it relates to shorts in the harness at the TB. It has not been to the dealer, I'd be broke at this point. Ecm has been replaced n flashed as has a crank relearn done.

[Swimmer8366]

Could have a problem with that wiring going to to the pedal. Hope you get it and don't have to sell after all that work.

 

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[Swimmer8366]

Have you had time to foul around with your truck was just curious if you've made any progress with checking out the wiring for the pedal.

 

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[tbarn]

not constant meaning at every start up but like I said about a dozen times per week. no not the pedal harness just the tb harness. And yes I know about the TSB and it relates to shorts in the harness at the TB. It has not been to the dealer, I'd be broke at this point. Ecm has been replaced n flashed as has a crank relearn done.

 

not constant meaning at every start up but like I said about a dozen times per week. no not the pedal harness just the tb harness. And yes I know about the TSB and it relates to shorts in the harness at the TB. It has not been to the dealer, I'd be broke at this point. Ecm has been replaced n flashed as has a crank relearn done.

Seems to me that you're going broke throwing parts at it.

[mkcom1]

other than to just take the connector off n check out the wires and pins no. with the connector at the tb there was nothing obvious or damaged on the connector or wiring. I replaced it anyhow and after the old one was off I took the time to strip each wire, I found one wire that was broken inside the sheathing. So that beening said unless you shot each wire and did a wiggle tes talong the length of each wire in my opinion its nearly impossible to find an open or short.

[Swimmer8366]

That's what your gonna have to do check each wire

 

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