GM Automotive Technicians Technical Discussion and Fixes for Nov 15, 2010 - iATN (Members Only)

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Open Help Requests for GM

	Help Request	Answers
	1997 Buick Regal GS 3.8L Cluster & Shifter VIN: 2G4WB52K9V We have a 97 Buick Regal that is possessed in the shop for a week already and need help from some of you experts. The vehicle was driven here with complaint of the vehicle dying, the instrument cluster blinking all of the lights (check engine, ABS, check coola...	View
	1997 Buick Century Custom 3.1L High speed fan inop VIN: 2G4WS5M3V1 Backprobed dark green wire at ecm pin 32. Shows ground with fan off and power with fan on this is for low speed. Backprobed dark blue wire at ecm pin 31 nothing no ground or power and no high speed operation. My question is does the power and ground come strai... Trouble codes: P1652 (Cooler fan 2)	View
	2003 Buick Rendezvous CX 3.4L idle air control VIN: 3G5DB03E13 When received the vehicle from customer, they complained that the engine was idling to high. Well,after some testing I found that the evac codes were present I cleared them and they read the same again.. It was then determined the throttle position sensor was ...	View
	1991 Cadillac Brougham 5.0L high idle VIN: 1G6DW54E6M Hello, Techs I am working on this cadillac Brougham for a high idle concern. The idle is reading 1200 rpm in park and wont idle down. I checked for vaccum leaks couldnt find any and we replaced the IAC valve. The tps angle is reading 0 percent at idle. Does an...	View
	1995 Chevrolet Tahoe 5.7L Surge VIN: 3GNEK18K3S Tahoe came in with a surge, miss, hesitation complaint. No codes. Found EGR opening right off throttle and stays open while driving. Scanner shows EGR duty cycle to be 100% along with the Purge Valve at 100% too. This occurs as soon at you give it the slightes...	View
	1999 Chevrolet S10 2.2L Instrument Panel VIN: 1GCCS1445X I usually specialize in electrical/electronic auto repair so I come across some good ones sometimes. This vehicle was brought in from a used car dealer. No drivability issues but on the instrument panel the following indicators stay on:Gate Ajar(this is regula...	View
	2001 Chevrolet Silverado 3500 LS 8.1L 3-4 shift, shift indicator VIN: 1GCJK39G91 Hello members. This is my own vehicle and ran into a problem on my way home. Stopped to pick someone up. Shut vehicle off, all was normal. When i restarted, Park indicator wasnt highlighted. Reverse highlights, 1st highlights, and 3rd highlights but 2nd, Park,...	View
	2001 Chevrolet Silverado 1500 HD LT 6.0L 4x4 shifting VIN: 1GCGK13U41 Hello fellow techs. I have this 01 Chev thats has got me going in circles. Customer came in with no 4x4 operation/noise from transfer case along with service 4wd light on. Found that the transfer case motor was not engaging and replace encoder/transfer case mo...	View
	2002 Chevrolet Express 3500 5.7L Misfire VIN: 1GAHG39R12 Hey everyone i have a fun one here. Have code po300 misfire on cylinder 4 and 7. Came in with engine knocking replace w jasper complete engine and install kit. Replace w updated fuel injector assembly, fuel filter, cap and rotor twice, distributor, used comput...	View
	2003 Chevrolet Blazer LS 4.3L No Start, Stall, Misfire VIN: 1GNDT13XO3 Customer complained that it died when put into gear, also stated that the oil pressure and rpm gauges went nuts. It doesnt start at all for me, I checked the crank and cam alignment and are in sync.I scoped the cam and crank signals and found a glitch in the c...	View
	2003 Chevrolet Blazer LS 4.3L No Start VIN: 1GNDT13X73 First time this truck has been in my shop. Customer was going down road and stalled, no start from this point. First i checked fuel pump, running fuel pressure in speck. Next used known good modual and coil, started up ran for 10min shut ut off. Restarted seve... Trouble codes: P1626	View
	2003 Chevrolet Silverado 2500 HD 6.6L Poor Idle Quality, Misfire VIN: 1GCHK23103 Owner states heavy exhaust smoke white/grey tint of blue. Shop confirms and noted runs clean cold. Engine oil a little low and no loss of coolant. No service codes and PCM not equipped with misfire monitor. Noted engine miss at idle to appox 1600 RPM then runs...	View
	2006 Chevrolet HHR LS 2.2L trans control and steering VIN: 3GNDA13D56 car came in from another shop with P0700 but could not read transmission codes. we found U0073 in transmission but have no info on this particular code. any help would be appreciated. thanks.	View
	2000 GMC Sierra 1500 SL 4.3L Cuts out VIN: 1GTEK14W2Y Truck come in with no start , had spark at the coil , but not the plug leads. Replaced cap and rotor and truck fired up. Keep in mind this truck is poorly maintained 23000 past its last oil change. So we talk to customer that a tune up is in order , replace pl... Trouble codes: P0339	View
	1998 Oldsmobile Regency 3.8L Misfire VIN: 1G3HC53K7W car came in with a miss fire on 1 and 4 swaped coil with a known good coil with no luck so i put an ignition module on it and the same problem happened so i went further and checked my grounds at module and computer all are ok also checked cam and crank sensor... Trouble codes: P0300 (Random cyl miss)	View

Fixes & Summaries for GM

	Fix/Summary	Answers
	2002 Cadillac Seville SLS 4.6L Mode Door VIN: 1G6KS54Y42 Our tech 2 does not have the ability to do bi-directional controls on this system so we will have to look into an update. However, after going thru data and the actual description of operation of the system we came to the conclusion that the system bleeds some...	3
	2009 Chevrolet Express 2500 6.0L Poor Idle Quality, Misfire, MIL Lamp on VIN: 1GCGG25U84 the negative fuel trims were being throwed off by a defective and sticking rich oxygen sensor on bank1 sensor1. This problem was most notable at warmer engine temps and while observing the fuel trim data you could actually watch the sensor stick around .8mv an... Trouble codes: P0172, P0300.	13
	1997 GMC C3500 Sierra SLT 6.5L Crank-No-Start VIN: 1GTHC33F2V Thanks for the direction. I removed the PDM from the pump, elongated the harness and mounted a new PDM on the firewall above the A/C accumulator.	19
	2001 GMC Sierra 1500 SL 5.3L t case VIN: 1GTEK19TX1 thanks to all of those that helped it was a compo of things on this one first it had been driven on a hunting trip and then also had to out of balanced drive lines and to bad u joints that you were un able to feel when checking them	15
	2002 GMC Envoy SLE 4.2L Unknown VIN: 1GKDT13S02 Thanks to all who replied. I disconnected drivers memory seat module and draw dropped down. After reconnecting I expected to see it return but it was gone. I let it sit over weekend with no problems at all. I checked the voltage on the alternator field wire am...	6

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