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post #1 of 97 (permalink) Old 05-27-2012, 10:39 AM Thread Starter
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Possible Bad Engine ECM?

Hello all. I could use some help on my 2010 cobalt w/2.2 dohc. I bought it as a rebuilder it was invovlved in a front end accident and was totaled. It only has 6,000 miles . I have finished the bodywork and have reassembled the car. the fuse block(that holds the engine ecm) in the engine compartment was damaged in the impact and the housing is cracked where it mounts to the frame. I am now experiencing 10 DTC's as stated by my hand held scanner. Car will run but when I clear the codes the car stalls and will not start for many attempts ..but will start and run after many attempts.
Codes are p0443,p0036,p0030,p0102,p0135,p0141,p0443(again) also the key faub will not work and the service air bag light is displayed in the info display as well as the idiot light.. I have blanks in the tire pressure info display as well and cannot get it to relearn the sensors on the tire. BY the way...air bags were never deployed. I am starting to wonder if the engine ecm took such a hit that it was scrambled????
Is there a way for me to diagnose the air bag system? and what do you guys think on all these trouble codes. I did have to weld on the car in that area as well. Can you give me some leads to try??ty ken from Coachworks bodyshop in Iowa.
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post #2 of 97 (permalink) Old 05-27-2012, 12:10 PM
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It appears one of your harnesses is disconnected because all these codes are related to engine. Check to the right front of engine for the harness containing MAF and HO2s wiring.Make sure all relays and fuses are seated in fuse block.

---------- Post added at 02:51 PM ---------- Previous post was at 02:47 PM ----------

Other problems appear to be related to BCM. So check the BCM fuse in the trunk beside the battery. I think it's a 50A.

---------- Post added at 03:06 PM ---------- Previous post was at 02:51 PM ----------

Make sure C1 & C2 connectors are well seated on the ECM Module. You might be missing a ground body to engine also.

---------- Post added at 03:10 PM ---------- Previous post was at 03:06 PM ----------

Check ground under fuseblock to see if wire wasn't pulled away from the lug.

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post #3 of 97 (permalink) Old 05-27-2012, 01:42 PM Thread Starter
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Checked mega fuse in trunk it was not blown. wiggled all relays. pulled grounds and cleaned .checked fuses in console .radio fuse was blown didnt notice any other bad ones ,checked fuses under hood none were bad. i had pulled harness connector and it wasnt clamped back in all the way...that gave me hope. got in started it still have codes but not as many...cleared codes with my hand held....it died....damn it... tried to start many times ,it did start again. but received pending codes which turned into DTC,s did manage to get tire pressure system to boot and I set all the tire sensors...radio works now. air bag service light still on...codes are nowp0443,p0030,p0102,p0135,p0141. checked on car parts.com and my local salvage yard has a engine ecm for $35.00 which i thought was super cheap. should i just get one? see what happens. the fuse block and ecm was right behind where it got hit...any thoughts??? PS i will try to get some pics of damage reapir for you guys..Ken from Iowa....shame im working on a holiday.... on a non paying job :[
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post #4 of 97 (permalink) Old 05-27-2012, 05:35 PM
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Did you take the covers off the two connectors going to the ECM to investigate and see if any wires had been ripped out in the impact? Because frankly you would need a huge impact to damage the ECM. Did you pull the ECM out to inspect for damage? But I'm still betting on a missing ground because P0102 code is missing low reference to MAF sensor, P0030 is open circuit to HO2 sensor 1 meaning either B+ or ground is missing my guess ground, P0135 is HO2 sensor 1 malfunction ( well without its ground reference it will malfunction),same with P0141 HO2 sensor 2 malfunction. P0443 is set because the car won't start within 15 seconds of first try so don't worry about that one for now.

Best bet check at MAF sensor connector for a ground on pin "B". And report back.

Mass Air Flow (MAF)/Intake Air Temperature Sensor
Pin Wire Color Circuit No. Function
A YE 492 MAF Sensor Signal
B BK/WH 451 Ground
C PK/BK 5291 Ignition 1 Voltage
D TN/BK 2760 Low Reference
E TN 472 IAT Sensor Signal



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post #5 of 97 (permalink) Old 05-27-2012, 06:23 PM Thread Starter
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TY coby . i have my multimeter handy. But I want to admitt i am a ASE master certified collision tech. my skills in electrical are limited. can you assist me on how to check that ground pin...with some direction i am sure I can do it..ty ken
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post #6 of 97 (permalink) Old 05-27-2012, 06:46 PM
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post #7 of 97 (permalink) Old 05-27-2012, 07:10 PM Thread Starter
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OK checkin back in. I put multi meter on setting that if you touch blk and red leads it will make a beep. i put the red lead on the pos post on the fuse block and inserted the black lead in the B pin on MAF and received a report of a beep. that must mean that the ground is working. Pulled the covers off the plug connectors to the ecm and saw no wires ripped out. I cheched the plug on the upper ecmbox (has single plug) what is that ecm called? cleared codes again and now in a no run situation...it will start but only for a momment. By the way impact was pretty bad...it broke spindle and drove wheel into the A-pillar and ripped the cv axle ujoint apart. I follow your lead coby...ty for your assistance. kenny

---------- Post added at 08:10 PM ---------- Previous post was at 08:03 PM ----------

man its hot here in Iowa today 95 and humid ....perhaps its a short from my sweat dripping on ecm...LOL suns going down though and its starting to cool thank goodness.
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post #8 of 97 (permalink) Old 05-27-2012, 07:33 PM
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First it should been from pin "B" to ground like engine or frame not B+ post. Check it again if you didn't burn your meter. lol.

One ground that often breaks in frontal collisions is the one that goes to the engine.
This is the best picture I could take of it.


---------- Post added at 10:33 PM ---------- Previous post was at 10:23 PM ----------

If it was hit on drivers side there is also a ground under the overflow reservoir attached to the fender well. I just noticed in the picture I just took that mine is turning green and will need a good cleaning soon before things start to act funny.



But this one usually affects lights on drivers side and wipers. Other stuff also act funny.

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post #9 of 97 (permalink) Old 05-27-2012, 08:13 PM Thread Starter
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I will check mine in the morning...ty for the great pics I replaced the unibody apron which is where the resivoure mounts I do not recall a ground there . this may be a good lead. will know more in the morning. I should get a tutorial on how to post pics here...i have a few of the repair i did on the body

---------- Post added at 09:13 PM ---------- Previous post was at 09:11 PM ----------

PS I didnt fry the meter...
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post #10 of 97 (permalink) Old 05-27-2012, 08:48 PM
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Gm refers to the first one as G105.


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Drives 2016 Sunset Orange Trax LT1 1.4L Turbo auto 3GNCJPSB8GL142716

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Last edited by Coby7; 05-27-2012 at 09:14 PM.
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