Check Engine Limp Mode and Won't start

[shirienchappell]

Dec/Jan, 2016/17, Check Engine Light and Limp Mode: Silverado

 

Dec, 2016: The "check engine" light came on on the way back from St. Paul, MN, and then the truck went into "limp mode". Also on that trip there were several days that the truck wouldn't start easily in the morning.

 

Dec. 16: In Elk City, OK, the truck started hard in the morning and then went into limp mode before we got back onto the freeway. We took it to the Gene Smith Chevy dealer. A tech. who read the codes said it probably wouldn't affect our drive home and reset the codes. He said the problem read out as being in the five volt system but that we very likely could drive the truck on home. When we turned it back on after he reset the codes the limp mode was gone. The truck drove ok for the next day but the check engine light came back on.

 

Dec 20: The truck did make it all the way back to Cottage Grove, Oregon, with the check engine light showing. Interestingly, when we unplugged the U-Haul car transport trailer the check engine light went away. We thought maybe the plug-in on the trailer might have caused a short in the truck system and when the trailer was gone, the short went away. Turned out that theory was wrong.

 

Dec 21: The check engine light came back on and the engine went into limp mode so we took the truck into Madras, Oregon, Chevy dealer who said Left it there for a few days, and then paid them $456.21. Here's what their bill says:

 

"Customer states when temps are in the range of freezing or below the vehicle will not start as if no fuel preheat. If is cool yet warmer than freezing and does start it will set a mil light and go into lip m0de. Diagnosis found multiple codes set, P03040, PO3041, PO193 and P2545. Bulletin existed to check wire harness for chafing, none found. Pressure tubes and sensors checked good. The fuel filter housing not holding pressure and the exhaust soot level high. We replaced the fuel housing and regenerated the Def system."

 

 

Tuesday, January 3, 2017: the check engine light came on again and the limp mode started again but we limped all the way in to the Bend Chevy dealer. The dealership didn't have any idea what was wrong, nor when we'd get the truck back.

 

Wednesday, Jan. 4: David from Bend Chevy says they've replaced one wire harness but think they need to replace another one, and it has to be ordered, but maybe Monday or Tuesday it might be done.

 

Wed, Jan. 11, 2017: Got a call from David from Bend Chevy this morning; said the truck was done. John paid Bend Chevy $656.75, and drove away. He didn’t get more than a block away before the check engine light came back on, so he went back to Bend Chevy. The read the error codes again and said it would take more time to find the problem. They’d had the truck for eight days so John brought the truck home. He asked how many miles the truck could be driven while in limp mode: no problems, he was told. Does driving the truck with the check engine light on cause a problem? None, he was told. If the limp mode comes on and John stops the truck and starts it back up again and the limp mode is gone, would that cause any problems. No, he was told.

 

"Date started: Jan 3, 2017

Date ended: Jan 11, 2017

 

A customer states the check engine light is on and vehicle has gone into reduced engine power. See attached for previous work performed. Advise.

Eng Diagnose short at SV Refence. Repair connector for brake pedal position 176077 CCRC

1 12672642 (S) Sensor

Parts: $41.75 labor: $614.00 Other: $0.00 total Line A: $656.75

 

114926 checked vehicle dtcs and found multiple codes stored as history including p0340, p0341, p0193, p2454, p0522, p0641, all of these codes are for the sensors on the 5 volt reference one. which means that a short to ground on one of these circuits or internal short on one of these sensors would shut down the whole 5 volt reference. The main connectors would set a p057c which is for the brake pedal position circuit. Disconnected the connector and performed a pin drag test everything was normal, opened the wiring harness and inspected wires found no faults, possibly another problem with the brake pedal position sensor circuit but could not duplicate code. Conditions were intermittent the only code that would consistently return would be for the cam position sensor. Inspected wiring and tested all there circuits to the cam position sensor and everything tested normal. Replaced cam position sensor wrapped the wiring harness and test drove vehicle. No further diagnostics unless codes come back and can be more persistent."

 

 

 

Note: as I look at the bill above I don’t see any wiring harness charges

 

Thursday, January 12, 2017: truck was plugged in all night; it started easily this morning and sat in the driveway, defrosting windows and warming up. When we started to back out of the driveway the limp mode and check engine light went on. John turned off the truck, tried to turn the truck back on, and it would not start.

 

If Chevy mechanics can't figure this out, what do I do?

 

any help? Thanks so much.

[O_J_Simpson]

You describe the truck as "Silverado" but we have no idea what model truck or power train you are trying to fix.

[Jsdirt]

Well first off ... and I tell people this ALL the time - DON'T go to a dealer unless it's under warranty or for a recall!

 

ANY small garage should have been able to troubleshoot this within 3 days and had it fixed once, for less than half what you've paid already.

 

Find a small garage with a good reputation. One that specializes in diesels, even better.

[shirienchappell]

You describe the truck as "Silverado" but we have no idea what model truck or power train you are trying to fix.

Oh. Sorry. Silverado 3500 Duramax 6.6 Diesel with an Allison transmission. 4 wheel drive, 4 door. Thanks.

[O_J_Simpson]

Oh. Sorry. Silverado 3500 Duramax 6.6 Diesel with an Allison transmission. 4 wheel drive, 4 door. Thanks.

Why is warranty not covering it? These engines eat injectors.

[shirienchappell]

It's got over 100,000 miles on it; warranty probably doesn't go that far...?

[Tyler Larson]

What did you figure out with this issue? My 2017 Chevy Silverado 1500 5.3L z71 is also having similar issues. I got the codes read and it says something about the Throttle Position Sensor. Does anyone concur?

[Supreme Pizza]

Those 6.6 diesels can be a nightmare. I personally do not work on them, due to the high level of failure and difficulty in troubleshooting. I know a guy that has one. I did replace a starter for him, but beyond that I wont touch it. He bought the truck, and so far he has not been able to drive it more than a few hundred miles. He has replaced both heads twice, along with a TON of other stuff. He has over $1,000 into towing bills alone, just getting the thing home time and time again. Several different mechanics and several different repair shops worked on it. It just sits in his driveway collecting dust. He kept saying that he has too much money into it to stop now, but apparently that logic did not work out well in the end. He has spent over $25,000 in repairs alone, and it still doesn't run reliably at all. That does not include the cost of buying the truck.