GM Automotive Technicians Technical Discussion and Fixes for Jan 16, 2007 - iATN (Members Only)

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Open Help Requests for GM

	Help Request	Answers
	1993 Buick Century Custom 3.3L Excessive Emissions, No Start, Poor Idle Quality, Surge, Cuts out, Stall, Misfire VIN: 1G4W092W0P car runs very bad cold pops through intake brakes up when you try to rev it up runs very rich. back fires through exhaust. problem will re occure after car sits outside in 2 hours after being at full operating temp when it is 29 out side. starts running bad as...	View
	1998 Buick Regal LS 3.8L abs VIN: 2G4WB52K8W Car sets code 1232 and 1225. Ohm check is ok, ac volt test ok. Abs light is on but on test drive scanner shows left wheel speed the same as rf, lr, rr. Can there be a short to ground or 12 volt if scanner will show correct wheel speed with the light on? If cod...	View
	2000 Buick Regal LS 3.8L No Start, Cuts out, MIL Lamp on VIN: 2G4WB55KXY Came in as a no start.Turn key it started with foot on gas.Iac was inop.ECM was not controlling IAC.Now it starts and runs BUT when you use turn signals it dies and won't re-start for a couple of minutes,won't even crank.When it does run runs well but shifter ... Trouble codes: U1000 (communication problem), U1040 (ebcm communication problem)	View
	1996 Cadillac Fleetwood 5.7L oil consumption VIN: 1G6DW52P3T this car is maintained on a regular basis. every three months or three thousand miles which ever comes first. customer came in at the end of november with add oil light on. changed oil and started oil consuption test, car uses one quart of oil in 998 miles. ca...	View
	1981 Chevrolet Corvette 5.7L head lamps VIN: 1G1AY8769B This car used to be a 1/4 mile drag car , completely stripped down just for racing . Now the owner wants to put it back original for the road. I need a vacuum diagram for the headlight opperation. I have 16 to 18 inches of vacuum . I can manually get them to g...	View
	1990 Chevrolet Corvette 5.7L Misfire VIN: 1G1YY238XL Hello all, I have a 1990 corvette that has 3 dead cylinders at all times, #5,6,7 CYLINDERS. Have scope tested igntion and even replaced all igniton components except internal distributor parts, have tested compression-good, have scope tested injector pattern...	View
	1995 Chevrolet Monte Carlo Z34 3.4L No Start VIN: 2G1WX12X3S i have a monte carlo with a 3.4 no start. when cranking engine, car will start for 5 sec and than dies immedietly. checked fuel pressure, and it's 40 psi. while cranking fuel pressure does not drop off. checked timing belt and timing marks, all ok. no codes pr...	View
	1996 Chevrolet Blazer 4.3L Rear Lift Gate VIN: 1GNDT13W3T Hello everyone, I have this 1996 Blazer in the shop and the rear liftgate won't open. When you press the dash switch you can here the lock operate inside the door. Whan you press the button on the liftgate you here the same sound. when trying a key in the tum...	View
	2001 Chevrolet Silverado 2500 6.0L Misfire VIN: 1GCHC29U11 This truck has a shudder when you pull a hill.I think it is a missfire.It is very consistent,fills exactly like you drove over those groves they put on the side of the highway.I Replaced plugs and wires with no change.fuel pressure is 55 koeo.I also cleaned in...	View
	2001 Chevrolet Silverado 2500 6.0L No Start VIN: 1GCGK29U51 Security Issues: Here's to the GM techs out there... This is the second time this year this has happened to me and it is gets very frustrating. Vehicle was towed in as a no start, immediately recognized it as a security problem, would crank and fire but shut d...	View
	2003 Chevrolet Astro 4.3L Misfire VIN: 1GNDM19X43 Ok guys i got one i can`t get rid of. this astro seems to drop a cylinder every once in a while at idle & seems to misfire under a light load at cruise speed. i have had my genesis hooked to it when it drops a cylinder & misfire under a load but it so slight i...	View
	1999 GMC Sonoma SLE 4.3L Steering VIN: 1GTDT19X4X Hello folks in iatn land. This truck will intermitantly seem to loose power assist during parking menuvoirs at any time any where. Does seem to happen more in reverse and close to lock. Ha anybody seen this? And what fixed it? Thanks for the help.	View
	2001 GMC Sierra 1500 SL 4.8L Hard start This one has a hard start (long crank) after sitting while hot it fires right up when cold or right after it's been shut off...but if it sits for a while it has a hard start... I was going toward a regulator leaking but I see no sign of leakage and it still do... Trouble codes: P0332 (Knock sensor performance)	View
	2002 GMC C6500 8.1L Poor Idle Quality, Hesitation, Stall VIN: 1GXG6H1E82 This tow truck has an 8.1L engine which stalls and backfires when cold. It also has low power when cold. It runs ok when warm but still has some loss of power even when warm. I supect low fuel pressure but we don't have the fuel pressure specs. Any help would ...	View
	1999 Oldsmobile Cutlass GLS 3.1L high idle VIN: 1G3NG52M7X dear techs this veh came in with high idle complaint.checked all obvious like vacuum leaks,iac operation.this problem occurs shortly after you start veh.the idle will go to 2500 and stay there.we can control idle using genisis spec test for iac position.it res...	View
	2004 Pontiac Grand Am SE1 3.4L No Start, extended crank VIN: 1G2NF52E34 Customer complains of an intermittent extended crank time when starting the car. This seems to happen under all conditions (hot, cold, etc). One time the car would only crank and not start (she said the theft light was NOT flashing), but when she tried it late... Trouble codes: U1000 (Loss of class 2 serial comm.), U1088 (Loss of SIR SDM comm.), U1128 (Loss of IRC comm.), U1040 (Loss of EBCM/EBTCM comm.), C1298 (PCM class 2 serial data link fault)	View
	2004 Pontiac Sunfire SE 2.2L Cuts out, Stall VIN: 3G2JB52F34 hello i have this sunfire thats suppose to stall and the re- start without a problem. i've drove this and have never had it stall on me ever.have checked fuel pressure (60) and lab scoped the pattern,it looked ok.scaned the computer, no codes& data looked ok ....	View

Fixes & Summaries for GM

	Fix/Summary	Answers
	1994 Chevrolet Camaro Z28 5.7L MIL Lamp on VIN: 2G1FP22P5R I have not fixed this yet. I did not receive any info that I had not checked into before. If anyone knows how this system check the knock sensor via the computer it might help. I have ordered anothe PCM and knock module. Such a simple system but unable to make... Trouble codes: 43 (knock sensor).	9
	1995 Chevrolet K3500 6.5L all brakes VIN: 1GBHK34F6S thanks to everyone that took the time to give us advise on this problem. abs unit was found at fault, special thanks to Raymond [...] for the quick response, did as you suggested and blocked off master cylinder and abs unit ports individully and found probl...	11
	1996 Chevrolet C2500 Cheyenne 5.7L Misfire, MIL Lamp on VIN: 1GCGC29R2T This one is fixed. Thanks for all of the replies. Most of the suggestions involved the fuel pressure regulator, and that's what it turned out to be. Before removing the plenum, I removed the throttle body and pressurized the fuel system. It was pretty easy to ... Trouble codes: P0172, P0175, P0300.	19
	1999 Chevrolet K1500 Suburban 5.7L No Start VIN: 3GNFK16R9X Thanks for all the replies. The customer nned the vehicle quicker than we were able to repair it so off to the dealer it went. We did though test the whole system and found that while cranking we had injector pulse and lost it when the engine started briefly. ...	11
	2001 Chevrolet Monte Carlo LS 3.4L Radio, headlight VIN: 2G1WW12EX1 Well I hope this one is fixed. My co-worker installed a new ignition switch and everything seems to be working fine, so far. I checked for codes and the only code was 'Oil pressure switch High Volts', I erased the code and it hasn't reappeared and it's been a ...	6
	2001 Chevrolet Silverado 1500 5.3L abs VIN: 2GCEC19V61 tHANKS once again for everybody's help. As it turned out it was the ebcm module that was shorted. Checked all the power and ground supplies. Replaced module did tests. Okay Jaime	12
	2002 Chevrolet Silverado 1500 4.3L security VIN: 2GCEC19W42 Hi all thanks to everyone who offered help. The problem was the BCM although it was new. The BCM is suppose to send the B+ to the passlock cylinder this was not happening. All grounds and B+ into the BCM were good, so I sent the BCM back to the Dealer in Flori...	13
	2002 Chevrolet Venture LS 3.4L Surge VIN: 1GNDUO3E32 WELL... IT'S FIXED. tHANKS TO ALL THE GUYS WHO OFFERED ASSISTANCE ON THIS ONE. I RECEIVED SOME GREAT SUGGESTIONS. IT TURNS OUT THAT THE VEHICLE HAD TWO PROBLEMS, AFTER SMOKE TESTING THE INTAKE AGAIN, I FOUND THAT SOMEONE HAD LEFT THE THROTTLE BODY BOLTS A LITT... Trouble codes: P0171, P0446, P0453, P0300, P0507.	12
	1999 GMC Safari SL 4.3L all guages and turn signals VIN: 1GTDL19WOX Most all of the replies were for the ignition switch, which is probably the culprit. Unfortunately the customer has not returned to try this fix. When he does return I will post an update!	9
	2005 GMC Sierra 1500 5.3L MIL Lamp on Found out the TSB on putting a heater that won't work until it's below 0 is correct. The engineer at the heater manufacturer said 'no way' couldn't be the heater but eventually we had four 05 and newer trucks in with same problem. Also, an 06 Equnix V6 that wo...	13

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