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2008 gmc 2500 reduce engine power
Wes1978 posted a topic in 2000-2014 Silverado & Sierra HDFirst time posting here, I’ve got a 2008 gmc 2500 6.0l, very very long story short I did a variable valve timing delete , mild summit cam, headers and injectors, I’ve had this thing to the tuner a dozen times and when the truck is running it runs like a bat out of hell but that’s only when it’s not going into reduce engine power randomly, I’ve replaced the wiring that goes to the throttle position sensor , the Throttle position sensor twice, gas pedal. My tuner can’t seem to help and he’s a reputable intelligent guy, if I could figure out how to control the 6l90 transmission I’d do a carb swap on this thing………… the only thing I’ve been able to figure out is when I’m driving down the road and it goes into reduce power I’ll pull over and relieve the fuel pressure by pushing the schrader valve on the fuel rail and it comes out of reduce power every time, I don’t know if that has anything to do with my problem ? Fuel pressure 60psi.
Check Engine Limp Mode and Won't start
shirienchappell posted a question in Ask the GM TechnicianDec/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.
Please Help. We're working on a 2001 Chevy Silverado 2500HD.It was stuck in limp mode. We first got the P0783-85 codes, so we replaced both shift solenoids, as well as the wiring harness. Still shot the same codes and was stuck in limp mode. So we replaced the transmission. Still didn't work. Now it's pulling up P1860 and both shift solenoid again. Also I realized it was shooting these codes before I even put it in gear. And that's what makes me think it's the ignition switch. Any help at all will be greatly appreciated and save my sanity.
Transmission stuck in high gear
VinceWeiss posted a topic in 1999-2013 Silverado & Sierra 1500I just put a new valve body in my 2006 Silverado with new accumulator pistons and solenoid’s and now that I have it all put together I went to drive it and it seems like it is stuck in a high gear like second or third and it has reverse has anyone had this issue before, is there some thing to reset like a transmission module?
4 cylinder Solenoid deactivation codes
socalcruiser posted a question in Ask the GM TechnicianI have a 2012 GMC Sierra with 5.3 Vortec. I had to replace one head due to damaged exhaust valve. Completed the work and truck is running but on reduced power. Code reader shows 3425-3441-3401-3449 which are the solenoid deactivation codes for the 4 AFM cylinders. I assume I have done something or missed something that is causing this to all 4 of these cylinders. Any suggestions on what steps to take to resolve? Visual inspection of wiring and vacuum hoses has found nothing. Oil was change with Mobil 1 and new filter. Possoibly in limp mode but these are only codes showing.
I have a 2005 2500hd duramax 6.6l LLy. I have been having a problem with my truck when I drive on the fwy doing over 65mph, the vehicle with go into limp mode and throws a ton of smoke. The only codes I get are for my mass air flow sensor, I've cleaned it several times and replaced it with a brand new one , and still no difference. I have a s&b intake with a S&b turbo mouthpiece, which I thought could be throwing off the mass airflow sensor, but those are the only upgrades I have on it. Cant seem to find a answer anywhere, figured I would try here. Any help is appreciated. Thanks!
James Dixon posted a topic in Gen III and IV Small Block & DrivetrainI’m at my wits end over this I’m not sure if it’s been discussed on here yet but I’m having a serious problem with my truck going into limp mode at random. I have a 2007 GMC Sierra, SLT, Z71 (newer body style) It runs fine for weeks, sometimes even months. Out of nowhere it’ll go into limp mode with these dash warnings: ”engine power reduced” ”traction control off” ”service traction control” ”service stabilitrack” Readings are: P2138 C0242 C0899 C0900 I replaced the engine due to a cam and lifter problem about 3 yrs ago. The truck started acting up about a month after the engine was replaced. The engine is still under warranty. -I’ve changed the gas pedal sensor. -I’ve changed the throttle body and throttle positioning sensor. -I’ve changed the electronic control module (ECM) -I’ve changed the electronic brake control module (EBCM) -I’ve even replaced the battery cables -I’ve added a new ground wire, thinking I had a bad ground somewhere. - I’ve checked and cleaned all connections into the throttle body, gas pedal, and all the plug ins I could see and get to. I had a guy tell me to look at the brake booster and possibly change that. It might be leaking or something. I’m not sure if that’s accurate advice and I haven’t done anything to the brake booster. Other than fooling with the brake booster, I’ve literally done everything I know to do except change the entire wiring harness!!! I don’t want to do that though. I love the truck and I don’t want to sell it but Im tired of putting money into it. Any help would be greatly appreciated. I’m on the verge of pushing it off of a tall cliff! help! - James