GM Automotive Technicians Technical Discussion and Fixes for Sep 14, 2011 - iATN (Members Only)

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Open Help Requests for GM

	Help Request	Answers
	1997 Buick Park Avenue Ultra 3.8L Stall VIN: 1G4CU5210V Today's patient is a high mileage supercharged Buick 3800. Customer came in last week with a complaint of eng stall. I did not get symptom but did have low/ unstable idle on decel w/ MIL (p0171 lean run)- AND +40% fueltrim @ idle. Found & replaced leaking gask... Trouble codes: U1255 (ABS module-class 2 comm fault), C1276 (ABS module- torque signal ckt fault), U1016 (BCM- lost comm with PCM), U1255 (ABS module-class 2 comm fault)	View
	2004 Buick Rendezvous Ultra 3.6L u1000/u1300 VIN: 3G5DB03784 this vehicle came in lots of lights on in dash and no gas or temp gauge working. put scanner on and have no class 2 communication and lots of other codes to do with communication u1301/u1300/p1629/u1040/u1064/u1000. these codes are in engine/abs/airbag/ipc/tpm...	View
	2006 Buick Terraza CXL 3.5L chime VIN: 5GADX33LX6 Customer complaint was that at random times while driving it will beep at her. I road tested and sure enough occasionally it will chime loudly twice while driving. No lights come on and nothing comes on the info center. I hear there are lots of issues with the...	View
	1999 Chevrolet Silverado 1500 4.8L Abs Module VIN: 1GCEK19V4X good afternoon everybody. have a major problem that i'd like to ask all the gm techs out there. have a 99 silverado that came in a couple of days ago with a code C0267 abs pump motor open.motor was running all the time. ran through the flow charts which lead m...	View
	2001 Chevrolet Express 1500 4.3L No Start VIN: 1GCFG15W01 The VTD system dose it disable both the fuel pump and injectors or just the injectors. This van came into our shop a no start, Cranks ok and has spark, but no fuel pump or injectors. Computer dose not turn on the fuel pump or let injectors fire. Computer shows... Trouble codes: P1631 (Theft code. Pass lock and computer not agree)	View
	2003 Chevrolet Blazer LS 4.3L No Start VIN: 1GNDT13W82 got an interesting one here. cust. brought to shop with crank no start, other tech checked and found battery dead. charged battery and car started right up. cust picked up and calls next morning with crank no start again. service run and checked for spark and ... Trouble codes: P0101 (Maf sensor)	View
	2003 Chevrolet Silverado 2500 HD 6.0L harsh shift VIN: 1GCHK23U63 Ok,here goes P0717-- input speed sensor..4L80E tranny...On the left side of trans, there is a place for the sensor but it is not there..In its place is a plastic dummy sensor,with no electrical connector,no wiring & looks like it is factory plug.. When you cle...	View
	2004 Chevrolet Express 3500 6.0L No Start VIN: 1GBJG31U94 Truck towed in for no start, cranks but kicks back. Scope cam and crank signals. When starter is jumped, so cranked without key, patterns look fine. Except they are both at about 8.5 v max. When cranked with key (alowing fuel) pattern looks ok exept that the h...	View
	2007 Chevrolet Uplander LS 3.9L instrument cluster VIN: 1GBDV13107 Not really A problem, I was wondering if anyone can tell me where I can get replacement bulbs? GM says you have to reman the cluster, but the bulbs twist in! not going to pay $350.00 for three light bulb . Any help is appricatied!	View
	2007 Chevrolet Tahoe LT 5.3L Hesitation, MIL Lamp on, Loss of power VIN: 1GNFK130X7 Truck brought to shop with codes po641, po606, po532, po107. As soon as you clear the codes, it may not come back for a couple of days. It normally happens when the car is idling on park. As soon as code po641 comes out, the reduce engine power in dash message... Trouble codes: P0641 (5v ref. 1 ckt.), P0606 (Control module internal performance), P0532 (A/c reference pressure sen. Ckt low volts), P0107 (Map sensor ckt. Low volt.)	View
	2008 Chevrolet Silverado 1500 LT 5.3L mode control and air temp VIN: 1GCEK14098 This truck when you fist start it in the mornings will have no control of the mode for heat defrost to change where the air comes from in the dash and you can not change the temp control eather it is stuck from where it was left from the night before but after...	View
	1997 Geo Prizm 1.6L No Start VIN: 12JW833EUE ok guys any help with this one will be greatly appreciated. this is my friends car and we are working on it at the house, so having said that i have limited access to scanner etc.. at home. ok this car is getting no spark and no injector pulse width, we instal...	View
	1997 GMC Savana 1500 5.7L Poor Idle Quality, Hesitation, Surge VIN: 1GBFG15R7U Good evening gentlemen.I have this van that idles rough for a few seconds then it clears up ALMOST entirely.It starts fine but you can see O2 sensors Bank 1 & 2 pegged high(readings 1076mv)stft go down to -80 then pcm goes open loop and van idles fine except i... Trouble codes: P0102 (maf ckt low)	View
	2005 GMC Sierra 2500 HD 6.6L Black smoke VIN: 1GTHK23295 Client brought in vehicle complaining of black smoke on accel. Confirmed black smoke with client and found it to smoke out a huge cloud of black smoke enough to blind and hide the vehicle next to me at a stop light. Started diagnosis with scanner hookup and ch...	View
	2007 GMC Acadia SLT 3.6L No Front Blower Motor Operation VIN: 1GKER33747 Costomer came in with no front blower motor operation. Removed blower motor and benched test ok. Have bright bright test light at blower motor purple wire and bright test light at black wire at blower motor. Scoped a blower motor speed control wire to find a v...	View
	2009 GMC C5500 Topkick C5C042 8.1L MIL Lamp on VIN: 1GDE5C1G09 THANKS IN ADVANCE FOR ALL YOUR HELP, This truck belong to us, drving down the road goes into limp home mode, pull over turn ign off for about 3-4 minutes it will drive normal again for a while, there is no pattern to this,we replaced throltle body few months b... Trouble codes: P1516 (Throttle Actuator Control TAC Module Throttle Actuator Position Performance), U0107 (Serial comm)	View
	2003 Hummer H2 6.0L Chain & Sprockets VIN: 5GRGN23U63 I have an 03 H2 with Borg 4484 transfer case. Vehicle has rattle sound out of the t-case above 15mph, most noticable between 15-30mph. Replacing the chain made it a little quieter but rattle is still there. Any wise words from you guys out there?	View
	2002 Pontiac Montana 3.4L trac control VIN: 1GMDX03E2D We replaced it with a used unit and when it was come it was working great. now customer returns and the traction control light doesnt come on in the dash when they switch it off and on mannually. with scanner hocked up and switching it the scanner shows it is ...	View

Fixes & Summaries for GM

	Fix/Summary	Answers
	2000 Buick LeSabre Limited 3.8L lifter noise VIN: F123456689 Thanks for all the help. Parts are on order. Although not yet running correctly we are confident that this will fix this issue. There are two types of gasket designs for this engine. We ordered the newer one. Other then the regular small things that break off ...	25
	1996 Chevrolet Camaro 3.8L Eats ignition coil's VIN: 2G1FP22K8T I would like to thank all 18 people who took the time to reply. I'm going to call this one fixed. I was leaning toward a PCM but it's frustrating when you can't actually "see" the problem or catch it on a scope etc. I had a very difficult time trying to measur... Trouble codes: P0300 (Random misfire).	18
	1999 Chevrolet Tahoe LT 5.7L Pedal Height VIN: 1GNEK13R1X There were lots of good replies to this, thanks everyone! This car had multiple brake probs & we never got it 100% fixed as customer ran out of willingness to follow it to the end. (he couldn't understand an over $2000 brake problems, however he has 300,000...	21
	2000 Chevrolet Tahoe 5.3L Hesitation VIN: 1GNEC13T0O First off, I would like to thank everyone that replied. Many thanks to Robert from Indiana, Timothy from Wisconsin & Timothy from Arkansas. Robert was first out of the box about faulty o2 sensors causing this problem. The strange thing about this being the pro... Trouble codes: P0301 (Misfire 1).	17
	2003 Chevrolet Silverado 2500 HD LT 6.6L Left front axle seal VIN: 1GCHK29173 Well after reading all the reply's, I had already hit it as hard as I thought I should have. I didn't feel like taking it out, so I cut a U shape hole in a piece of 3/8" steel, put it behind the flange, put all but one of the bolts back in the flange and tig...	13
	2005 Chevrolet Silverado 3500 6.6L Hesitation VIN: 1GBJC39245 I want to start by thanking everyone for their help. It was the wrong crankshaft reluctor wheel installed on this engine. After we installed the correct reluctor wheel and reassembled the vehicle, it fired right up. I spoke to my local JASPER sales represen... Trouble codes: P0335 (Crankshaft position sensor circuit), P0336 (Crankshaft position sensor performance).	8
	2008 Chevrolet Express 3500 6.6L starter VIN: 1GBJG31658 Had to send the vehicle to the dealer because the problem was the ecm and it was still under factory warranty. It is what turns the starter micro relay on in fuse box. The ecm had to be replaced. The engine starts every time with no problem. Getting to be ridi...	4
	2002 GMC Savana 2500 5.7L Rear brakes VIN: 1GTGG25R32 We finally fixed this vehicle. We replaced the hardware on the rear. No change. We then machined both rear drums that were new. They were definetly out of round. That got rid of the shuttering in the rear, but the rear brakes would just lock up and overheat at...	16

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