GM Automotive Technicians Technical Discussion and Fixes for Jan 24, 2008

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	Help Request	Answers
	1988 Buick Century Custom 3.8L Cuts out, Stall VIN: 1G4AH8131J this came in from another shop. sometimes when comeing to a light it stalls. it will fire right back up. it never runs bad just stalls. it has no codes. the coils ohm at 6200-6800. the things i noticed are on the scanner the batt volts drop to 0 when it stalls...	View
	1988 Buick Reatta 3.8L No Start VIN: 1G4EC11C0J We have a strange one here, this car will act like its out of time, when trying to start, it will backfire through the intake. it has blown the air filter box apart. if he keeps tring it will start, although we cannot get it to start at this time. we thought m...	View
	2001 Buick Century Custom 3.1L Sets code VIN: 2G4WS52J21 This has no symptoms other than a CES light that comes on intermittently and only for the customer. It was my recommendation to replace the sensors, which the customer was fine with, however, problem not solved. The P1189 I'm not sure If I'm to worry about thi... Trouble codes: P0336 (Ckp pos sensor fault), P1189 (O/P sensor circuit)	View
	1996 Cadillac Seville SLS 4.6L every thing electrical VIN: 1G6KS52Y4T vehicle came in with intermitent no start no crank, only thing that seems to be working is the p on the prndl lights up,nothing else electrical seems to work.do not want to spend half aday searching for this issue,hoping somebody else has run into this problem	View
	2003 Cadillac CTS 3.2L MIL Lamp on VIN: 1G6DM57N53 I just finished doing some work on this Caddy, I am unable to find the correct procedure to re-learn the throttle actuator. I tried Mitchell and Alldata but could not find the correct procerdure. Thanks for you help. Trouble codes: P2101, P2119	View
	1989 Chevrolet C1500 Cheyenne 5.7L No Closed Loop VIN: 2GCEC14K0K Well..., ECM never enters Closed Loop. Data stream showed coolant temperature at 145Deg and steady, so we changed thermostat. Now it shows coolant temperature above 195Deg; MAP voltage about 0.9vdc; O2 voltage normal at idle. At cruise, O2 voltage drops off to...	View
	1989 Chevrolet K3500 Cheyenne 7.4L Poor Idle Quality, Hesitation, Stall, MIL Lamp on VIN: 2GCGK39N8K this vehicle came in for poor run. First it recieved a tune up (cap, rotor, plugs, and filters) still poor run. It has been through 4 techs and has had a new camshaft (old one had 3flat lobes) and lifters, injectors cleaned and flow tested, new iac, new map sn... Trouble codes: 44 (lean exhaust)	View
	1993 Chevrolet Corsica LT 3.1L stays runnin VIN: 1G1LT53TXP This car has an intermitant problem, it will stay running after the key is removed, it will not do this problem in the shop, and may go away for a month or more, or act up 2 times a day. If the key is turned on and off a few times the car will shut off. The ke...	View
	1994 Chevrolet S10 Blazer Tahoe 4.3L Excessive Emissions, Poor Idle Quality, Poor Fuel Economy VIN: 1GNDT13W0R Hello, Hope to get some help, this car came in not running flooded. we put plugs in got it running, it ran only at raised rpm, running very rich, (we then replaced injector) OEM part. Still runs just as bad, no codes, if we give it a vac leak taking off brake ...	View
	1997 Chevrolet Astro 4.3L t.c.c. pulse width modulator VIN: 1GCDM19WOV vehicle originally came in with a abs light on . had no communication with abs computer . i found a blown fuse #18 brake in the ip fuse panel . had a rear speed sensor code . tested speed sensor and all appeared normal . cleared abs code . when i installed new...	View
	2000 Chevrolet Malibu 3.1L Unknown VIN: 1G1ND52JXY This malibu came in with a noise of a bad wheel bearing. When turn to the right noise goes away, when going straight or turn left noise remains the same. After replacing both wheel bearings we still have the same noise. Any help from you transmission guys woul...	View
	2002 Chevrolet Trailblazer LS 4.2L MIL Lamp on VIN: 1GNDT13592 A good cust. called yesterday from work parking lot with mil on and reduced power lite on. I told him too tow it over. He did and when it got here we checked codes and had po507 and po601. , also he drove it here in low range at 5 mph. we cleared codes shut it... Trouble codes: P0601, P0604, P0606, P0607	View
	2003 Chevrolet Monte Carlo SS 3.8L front timing ch/balancer VIN: 2G1WX12U03 Vehicle has been having problems in the last 2 weeks. we've been down to 15 Deg above and below zero the last month. The fist notice for the customer was when accelerating onto the freeway it was losing power and would hardly get up to 70 mph. as it has progre...	View
	2004 Chevrolet Trailblazer LS 4.2L sputters VIN: 1GNDT13S14 hello to all here at iatn and thanks in advance for reading my post. 2004 trailblazer i have this car here that is giving me problems need help. i get a consistent p2135 and p2138 that keep returning on this thing i've ohm out all the wires to my app sensor th... Trouble codes: P0495 (cooling fan speed high), P2135 (tps 1-2 correlation), P2138 (app sensor 1-2 correlation), P0641 (5v ref. 1 circuit), P2122 (app sensor 1 circuit low), P2123 (app sensor 1 circuit high)	View
	2004 Chevrolet Silverado 1500 LS 5.3L 4x4 VIN: 2GCEK13T04 Good Day, I have this Silverado in for service 4x4-encoder circuit malfunction. Switch lights up with(this is auto4x4) key on,then all go out. I was hooking up dvom for 5v reference testing and I had it-but!!! the key is off. I can communicate with transfer ca...	View
	2004 Chevrolet Cavalier LS Sport 2.2L modes cable VIN: 1G1JH52F64 Hello! Vehicle came in with complaint of modes not working correctly. Upon inspestion found that mode cable was kinked at control head. Replaced cable from dealer and modes worked, but seemed alittle stiff. Customer took vehicle and all was fine until today. V...	View
	2004 Chevrolet Tahoe LS 5.3L 4 4 system VIN: 1GNEK13Z04 i need some help on a electronic transfer- case problem , has a code co237 stored in history, encoder circuit, customer says at times cant shift out of 4 hi , not been able to duplicate problem yet, but thought i get some input first, any help would be great,	View
	1993 Oldsmobile 98 Regency 3.8L Cuts out, MIL Lamp on VIN: 1G3CW53LM4 Hey guys i have this olds that i can't seem to figure out. It was towed in not running. the customer is not much help but here's what i know. The car will quit while driving. Had it towed to a shop and they put a ignition module / coil assembly on it. customer... Trouble codes: P0041	View
	1995 Oldsmobile Aurora 4.0L Hesitation, Stall, Misfire VIN: 1G3GR62C2S Car has misfire cond. seems worse coming off idle at approx 1100 rpm. Clears out higher RPM. Veh has flap at end of intake plenum, seem to have minor leak during smoke test, not sure if normal, have ck'd cam and crank signals ok, Ignition wires and plugs repla...	View
	1995 Oldsmobile Achieva S 3.1L No Start VIN: 1G3NL55M6S Please help this one is driving me crazy, Customer complains that car is very hard to start when the engine is cold. After it cools down a couple of hrs. it will start after a long period of cranking, the colder it is out the longer it takes to start, at 40 de...	View
	2000 Pontiac Grand Am GT 3.4L Stall VIN: 1G2NW12EXY This car will shut down while driving down the road.When it shuts down the speedo quits also even though you are still moving.If you wait 5 mins. It will restart and run for a few miles then do the samething all over again. It has no codes.	View
	2002 Pontiac Aztek 3.4L odometer light VIN: 367DA03E62 Hi GM Pro's, the odometer reading is working just fine, BUT the back light illumination on the odometer reading is NOT working...as I understand, I have to try to SELL another complete cluster. How do I tell the customer that there is NO bulb or LED to replac...	View

Fixes & Summaries for GM

	Fix/Summary	Answers
	2001 Buick Regal LS 3.8L temp in car VIN: 2G4WB55K71 WHAT TO THANK YOU FOR THE REPLIES THAT I GOT, IT DID HELP TO FIX THE PROBLEM, FOUND THE WIRES GOING TO THE TEMP SENSOR BY CONDENSER HAD BARE SPOT WORN IN THEM BY RUBBER AIR DAM. REPAIRED AND THAT FIXED THE PROBLEM, THANK AGAIN FOR THE HELP.	5
	1994 Cadillac Seville STS 4.6L Blower Motor VIN: 1G6KY5290R It's fixed. The blower module is in the blower motor. As most of you said this was the problem. Expensive repair. Thanks to all that replied. Special thanks to Gary for the easy test & to Juan for the removal tip. Bill	21
	1997 Cadillac DeVille 4.6L instrument cluster lights VIN: 11G6KF5491 Thanks to all. It was the twilight photocell sensor that was bad. Replaced it and light work fine	3
	1997 Chevrolet K1500 4.3L Hesitation, Misfire VIN: 1GCER14W7V Sorry for the delay. Since the fuel pressure was dropping at KOEO and also the fuel gauge was not working, I decided to replace the fuel pump as some of you recommended. Fuel gauge is working now and the fuel pressure changed just a little bit. Someone asked ... Trouble codes: P0172 (A/F ratio B1 too rich), P0175 (A/F ratio B2 too rich), P0300 (Random misfire).	13
	1998 Chevrolet Metro LSi 1.3L No Start VIN: 2C1MR522XW For starters, I'm sorry I forgot to mention that I was all over the injectors looking for problems, all of them checked out good. The fix ended up being a strange one. The crank signal was not exactly as strong as it should be and that was due to increased a...	5
	2000 Chevrolet Astro 4.3L No Start VIN: 1GNDM19W0Y Thanks everyone for the quick replies. The problem turned out to be a faulty coil. We were getting 20KV on our scope, and we assumed that this would be enough. We were wrong! A brand new coil and module shows 45KV output and the truck lit instantly after w... Trouble codes: P0300 (Random misfire).	24
	2000 Chevrolet Silverado 1500 5.3L Misfire VIN: 1GCEK19T2Y I'm sorry that I can't post this as a fix, but I have learned a lot. especial thanks to Kent for sticking with me through all of the testing that I did. In the end, I guess that the problem would be resolved through a teardown of the engine. the main indica... Trouble codes: P0300 (Random multiple cyl misfire).	31
	2003 Chevrolet Silverado 2500 6.0L speedo and tach VIN: 1GCHK29U53 WOW, I HAVE NEVER GOTTEN SO MUCH HELP SO FAST. ALL RESPONCES WERE THE SAME IT IS A BAD DASH UNIT. WE HAVE A NEW UNIT COMING FORM THE DEALER IT WILL BE HERE TOMORROW AND THIS TRUCK WILL BE BACK ON THE ROAD. THANKS AGAIN FOR MAKING AN OLD MAN LOOK SMARTER THAN H...	33
	2006 Chevrolet Trailblazer LT 4.2L Starting VIN: 1GNDT13SX6 ok this one is fixed. checked voltage at signal wire for starter signal in start to see if it had voltage in run, it did not. figured everything looked fine there. also didn't state another problem that this had of wipers inop. took a chance on getting a n...	10
	1989 GMC Safari SLE 4.3L Overheat VIN: 1GKDM15Z4K I would like to very much thank all those that replied to my post –I've looked into each and every reply. The elderly couple that owns the vehicle has been very patient and understanding. I only get the vehicle for tests a few days a week to run tests/checks. ...	11
	1993 GMC K3500 Sierra 5.7L Pressures/shift VIN: 1GDJC34K3P Good Good news, after chatting with the trans shop after the truck was returned to them from the dealer, the trans shop said what the hey, and tried a second hand computer from the wreckers (keep in mind it had both an aftermarket and a GM computer and memcal ...	3
	1995 GMC K2500 Sierra SL 5.7L Poor Idle Quality, Surge, Cuts out VIN: 1GTGK24K55 well this ones fixed, had 13 very quick replies most suspected fuel concern as i did however after swapping tbi, map ect from my personal truck we had same concern, all pcm grounds at front of intake had already been cleaned ground at rear of rh cylinder head ...	13
	2002 GMC Envoy SLE 4.2L battery VIN: 1GKDT13512 consulted chevy dealer about problem was told that they dissconect every module and reconnect one at a time until draw returns problem was with liftgate module and they are hard to get because its a common problem but not posted as bulletin or recall yet than...	6
	2004 GMC Sierra 1500 SLE 5.3L looses ps assist at idle VIN: 2GTEK19T74 Great replies all- We used a new GM ps pump & it fixed problem- the reman Napa pump was not cutting it.	12
	1993 Oldsmobile 98 Touring 3.8L steering VIN: 1G3CV5313P This one is fixed. Of course talking with the customer he wanted to try to flush the ps system and try the Lucas treatment. Saw no change in steering effort and the problem when braking remained the same. I should have mentioned that the tires were bald due to...	7
	2002 Oldsmobile Alero GL 2.2L Excessive Emissions, Poor Idle Quality, Hesitation, Misfire, Poor Fuel Economy, MIL Lamp on, P0300 I would like to thank everyone who took the time to help me. In short, the problem was the ignition module. After I replaced it I checked the vacuum and had 18 inch at idle. I guess what through me off was the low vacuum pressure. I did not think a secondar... Trouble codes: P0300 (Random Misfire).	8
	2004 Pontiac Grand Prix GT1 3.8L Cuts out, MIL Lamp on VIN: 2G2WP52214 well we replaced maf sensor. vehicle has been gone a whole week. still no problem. will call this a fix. i am so glad i did not replace the pcm. thank you all you gm techs. the best website ever. Trouble codes: P1106 (maf ckt intermittently high).	8
	2000 Saturn SL2 1.9L starting VIN: 1G8ZK5279Y Thanks to all, we replaced the coil, customer has had car for 2 wks no problem, this was a updated part no. from saturn.	5
	2002 Saturn SL1 1.9L Forward Engagement VIN: 1G8ZH52832 We never did actually find a "smoking gun" on this unit. Physically, nothing looked bad. As per most responses, we installed a new valve body and solenoids. We also installed a new forward sprag assy. The customer has had the car for about two weeks. He came i...	9

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