GM Automotive Technicians Technical Discussion and Fixes for Dec 15, 2008 - iATN (Members Only)

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Open Help Requests for GM

	Help Request	Answers
	1995 Buick Riviera 3.8L aLTERNATOR VIN: 1G4GD2216S This Riv came in not charging and we found out that it has the exciter wire, terminal "L" controlled by the ECM. The boss jumped to the alternator on that terminal and it would charge and continue to charge as along as the engine was running. The ECM had some ...	View
	1997 Buick LeSabre Custom 3.8L No Start VIN: IG4HR52K3V This is my personal vehicle. I mostly work on imports and thought a GM person might be able to steer me in the right direction. The car has a hard start condition when cold and sometimes warm. The engine will crank over for a long time before firing. It will...	View
	1999 Cadillac DeVille 4.6L Excessive Emissions, Poor Idle Quality, Misfire, MIL Lamp on VIN: 1GEEH90YXX Any Cadillac guru! I need your help... 99 Cadillac Deville 4.6 liter. Will not pass emissions due to miss fire. Vehicle came in with codes up the ying yang. Everything that has been has help but not there yet. Compression check good. 135 is the compression.... Trouble codes: P0300	View
	1989 Chevrolet Camaro Iroc-Z 5.0L Poor Fuel Economy VIN: 1G1FP21F2K Help, been fighting this car for months. the owner brought it in for poor mpg, running rich. owner says it gets 9 mpg. runs great on road but fouls o2 sensor immediately. Check fuel pressure-normal,timing-correct. check o2 sensor- dead. replaced o2 sensor and ...	View
	1992 Chevrolet Corsica LT 3.1L No Start, Poor Idle Quality VIN: 1G1LT53T2N car came in with no start after hot,no codes,no crank rpm,changed crank sensor,starts ok,but seemed to floodand cust noted after the fact it alwys ran hot,changed t/stat,runs cooler but no fan,ground relay fan runs ok.checked for ect reading seems ok but when ...	View
	1994 Chevrolet C1500 5.7L Hesitation VIN: 1GM35FG354 Okay so I replaced plug wires, cap, rotor, plugs, air filter, fuel filter and added seafoam. Checked fuel pressure and it,s good. so it stumbles on it's face when you give it full throttle or even half but when you let off on the gas a little it will kick in. ...	View
	1995 Chevrolet K2500 5.7L Hesitation, Surge, Cuts out, Stall VIN: 1GCFK24K5S This one come to the shop with a stall concern when put into drive and a no power concern when accelerated. We found the pcv port on the tbi to be pluged rebuilt tbi unit and replaced pvc this for the most part stopped the stalling. tune up was out of whack so...	View
	1999 Chevrolet S10 4.3L MIL Lamp on VIN: 1GCCS19X68 Here is a good one. This vehicle came in with a P0131 (Bank 1 Sensor 1 Low Voltage). Found and repaired open Hi signal wire (purple)from O2 sensor to PCM. After repair, scantool indicated a fixed 450 mv reading. A back probe reading at the PCM indicated a fluc...	View
	2002 Chevrolet Blazer LS 4.3L oil pan VIN: 1GNCS13W22 Hello fellas. This is my personal vehicle which developed a oil leak the same week i switched to mobile 1 synthetic 5w30 (coincidence or not!) i believe its leaking from the right rear corner of the oil pan. i removed the cover in the trans bell housing and lo...	View
	2003 Chevrolet Avalanche 1500 5.3L starter motor VIN: 3GNEK12T56 Hi This truck has a qwueer problem with the starter. It stops half way through the start cicle. The negative signal that goes to the starter relay from the PCM when you apply the key disappears and the relay disactivates. The positive signal from the key to th...	View
	2003 Chevrolet Silverado 1500 4.8L Misfire, MIL Lamp on VIN: 1GCEC14V43 Hello all, thank you for taking the time to read, I have a 03 chev picup (owner of the shop truck) that is going to drive me nuts, have a misfire on #4 and #6 all the time, i have fuel, spark, and compression, i have removed the valve cover and checked the roc... Trouble codes: P0304 (Cylinder 4 misfire), P0306 (Cylinder 6 misfire)	View
	2004 Chevrolet Colorado LS 3.5L ecm VIN: 1GCDT13694 some times on startup cel comes on engine goes into reduced power turn key off restart runs fine no cel this has got me stumped any ideas thanks.	View
	2007 Chevrolet Monte Carlo LS 3.5L Excessive Emissions, MIL Lamp on VIN: 2G1WJ15KX7 Hello fello iATN members. This Monte Carlo is giving me some unknown grief. The engine runs rich at all times, enough to set a code in idle or non-idle conditions. The engine seems to run ok, no hesitation etc. I have not been able to determine anything wrong ... Trouble codes: P0172 (Engine rich bank 1)	View
	1999 GMC Yukon Denali 5.7L Back Up Lights & Instrument Lights VIN: 1GKEK13R2X Hello and Merry Christmas Fellow Technicians, We have this 99 Denali that has the back up lighs remianing on all the time. The wiring dighram shows that it is involved with the power/auto mirrors. We have eliminated the reverse switch and headlight swtich by d...	View
	2000 GMC Sierra 1500 SL 4.3L Excessive Emissions VIN: 1GTEC14W6Y hello folks. this truck is not closing any OBD monitors and needs to be smogged. no drivability symptoms and no codes present.the only symptom is a whacky ipc. the battery light is always on, despite a good charging voltage, and the temp gauge and fuel level g...	View
	2006 GMC Yukon Denali 6.0L Rear HVAC temperature blend door actuator VIN: 1GKEK63U96 It would be easy to blame the "Evil Car Gods" for this one but we all know that is not the case. A new customer brought vehicle in to have the rear HVAC temperature control repaired. He said he was supposed to bring it in to a local GM Dealer who just closed t...	View
	1992 Pontiac Grand Prix SE 3.1L wont move unless cold VIN: 1G2WJ14T8N Hey folks. Not very much experience in transmissions but here it goes. The car has done a hesitation when shifting in reverse for a couple of seconds for probably a year. The fluid is red and I already replaced the tcc solenoid about a year ago. But this morni...	View

Fixes & Summaries for GM

	Fix/Summary	Answers
	1996 Buick Skylark Limited 2.4L dash lights VIN: 1G4NJ52T6T the problem was in the data line loosing comunication to cluster from pcm under the passenger seat there is a sdm module air bag module water got in it and shorted it out that was replaced cleaned connectors and on its way it whent	4
	1980 Cadillac DeVille 5.7L Brakes Apply when started VIN: BD69NA9213 Hey All, Thanks for all the replies but it appears I missed something. While pressure bleeding the brakes I noticed the flow was poor out of the rear wheel cylinders so I started undoing lines until I found adequate brake fluid. As stated the system was ...	13
	1991 Chevrolet K1500 Cheyenne 5.7L Misfire VIN: 2GCEK19K0M Hey guys. Here is the lowdown on this pickup. The misfire is always present, and most noticeable on idle, but also there under load. This means that for the most part, a vacuum leak is not likely the cause. I received replies to block off the brake booster...	24
	1994 Chevrolet C1500 5.0L Unknown VIN: 13MV456GH6 transmission filter fell off, replaced filter and fluid , working fine now	6
	1999 Chevrolet Cavalier LS 2.2L hard start VIN: 1G1JF5245X GREAT RESPONSE AS ALWAYS FROM IATN MEMBERS. RECEIVED 12 REPLIES WITH RECOMMENDATIONS VARYING FROM FUEL PRESSURE CHECKS, LEAKING #4 INJECTOR AND FUEL PRESSURE REGULATORS. PHILLIP [...] ALL HIT THE NAIL ON THE HEAD. THE C...	12
	2001 Chevrolet Silverado 2500 HD 6.6L 4wd VIN: 1GCHK24G71 IT WAS THE ENCODER THE REASON I PUT THE MODULE IN,(I DID TRY A SWITCH FIRST)KOEO WITH SOLIS INSTALLED FOR BIDERECTIONAL TESTS.I COULD NOT TURN THE LIGHTS ON THE SWITCH.MITCHELL DIRECTED ME TOWARD THE MODULE THEY DID HAVE YOU DISCONNECT THE ENCODER AND USE SCAN...	11
	2004 Chevrolet Malibu Maxx LS 3.5L steering VIN: 1G1ZT64834 Customer think it is better The steering position sensor was calibrated and centered (need a tech 2)to do this I also crossed the front tires with esch other I still thought it was pulling, but customer is happy Thanks to the guys that emailed me. Hope I can r...	5
	2004 Chevrolet Tahoe LS 4.8L Starter VIN: 1GNEK13V64 Well, I am forced to close this help request due to the rules of membership. I am not completely confident in this truck being fixed. Truck ended up at 2 dealships. Both wanted to 'throw' a starter at it. They never could get the truck to not start but still w...	10
	2006 Chevrolet Equinox LT 3.4L Temp Air Door VIN: 2CNDL63F56 Thanks for the help. Most replies said to assemble the car to a point where all power could be hooked up and move door motor with a scanner or the cars control. And some said to buy a new motor and it would be in a position that could be installed. Also som...	6
	2007 Chevrolet Suburban 1500 LTZ 5.3L traction control VIN: 1GNFK16307 well every body was correct that code c0561 was just set because of codes in the pcm. i did have two codes a 171 and 174 lean codes both caused by an incorrect ethanal content in the tank. it is a flex fuel vehicle but it was reading 15% when ethanol content ...	6
	1999 GMC Sierra 2500 SL 6.0L No Start VIN: 1GTGK29U3X Thanks to all that replied I honestly don't know at what step I fixed the passlock problem the body control I think (it was full of water) but this truck was doing the same identical thing firing and stalling after a weekend to clear my head I went back to rec... Trouble codes: P1626.	5
	1989 Oldsmobile Delta 88 Royale Brougham 3.8L blower motor control module VIN: 1G3HY54C8K checked the amp draw of the blower motor on high speed, was 14 amps - should be ok. found fresh air intake vents clogged with leaves / debris. thinking maybe causing blower module to overheat. installed another module and cleaned debris. so far repair seems su...	8
	1998 Oldsmobile Intrigue GL 3.8L abs VIN: 1G3WS52K5W Andre hit this one out of the park!!! Replaced bad left front hub problem gone. Old hub tested perfect for all tests but new one fixed it. Thanks for all the great info people!!! Hope I can help someone down the line. Happy Hollidays to all!!!	5
	2001 Oldsmobile Intrigue GL 3.5L eng had to use a air lift tool borrowed one from a friend work like a champ thanks for all the replys.	21

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