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07 SS, drove home one day, next day no start, gear range letters/numbers lit up, no outline box indicating gear selected. Turned key to start, dash went out and headlights dimmed, no starter click.
Jumpered starter relay in fuse box, starter cranked over but wouldn’t start with key on.
I get service brake assist and traction control messages on DIC, plugged in my Matco E123 scanner and get no communication message.
I have to suspect ECU is the problem.
Anyone else had this issue or repair reccomendations?
 

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162487
I would check the grounds near the starter (picture is for reference) v8 are in similar position, wiggle them and have someone on the inside check the scanner , also check the one by the battery to radiator support. I've been chasing an electrical Gremlin for a few months now my next option is to bypass neutral safety switch to see if that's the culprit.
 

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View attachment 162487 I would check the grounds near the starter (picture is for reference) v8 are in similar position, wiggle them and have someone on the inside check the scanner , also check the one by the battery to radiator support. I've been chasing an electrical Gremlin for a few months now my next option is to bypass neutral safety switch to see if that's the culprit.
Thank you for the reply.
I don’t mean to be rude but, as I mentioned in my post, I jumped the starter relay in the fuse panel and the starter cranked over.
I was thinking neutral start switch as well, but after searching and seemingly reaching the end of the information highway there doesn’t seem to be two people who agree on this
 

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Thank you for the reply.
I don’t mean to be rude but, as I mentioned in my post, I jumped the starter relay in the fuse panel and the starter cranked over.
I was thinking neutral start switch as well, but after searching and seemingly reaching the end of the information highway there doesn’t seem to be two people who agree on this
A dodgy ground to the BCM, ECM & TCM doesn't mean you can't run the starter using brute force.
If you bypass the control modules by jumping terminals in the fuse panel you can make the starter crank with the BCM & ECM unplugged. All you need is the big fat 4ga cables and the 10ga hot connection to the fuse box attached on both ends.
The big fat 4ga electron hoses from the battery to the starter and the block generally don't give much trouble.
Those unsealed ring terminals with little 16ga & 18ga grounds for various control modules can and do break and corrode right where they connect to the front of the transmission. It's a known problem with the 8th gen Impala.

Get out your meter and test light so you can test the basics.

Terminal 4 on the OBD II J1962 diagnostic jack is Chassis ground.
Terminal 1 is Ignition Switched power.
Terminal 16 is Battery power.
Terminal 5 is a digital ground... This is the control modules logic reference ground not a chassis ground... there is a diffrerence. DO NOT test this terminal with ham handed equipment like a meter or test lamp.
Terminals 10, 6, & 14 are data lines. You can look for activity on these connections with an oscilloscope or a logic probe.

-Test from 16 to a body ground with your test lamp. The lamp should light.
-If 16 and body ground lights the test lamp test from 16 to 4.
-If the light doesn't light check the resistance from terminal 4 to a body ground with your meter then find and fix the damaged ground.
-If the light works then turn on the ignition and test from 4 to 1 with the test lamp.
162491
 
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Discussion Starter #5
A dodgy ground to the BCM, ECM & TCM doesn't mean you can't run the starter using brute force.
If you bypass the control modules by jumping terminals in the fuse panel you can make the starter crank with the BCM & ECM unplugged. All you need is the big fat 4ga cables and the 10ga hot connection to the fuse box attached on both ends.
The big fat 4ga electron hoses from the battery to the starter and the block generally don't give much trouble.
Those unsealed ring terminals with little 16ga & 18ga grounds for various control modules can and do break and corrode right where they connect to the front of the transmission. It's a known problem with the 8th gen Impala.

Get out your meter and test light so you can test the basics.

Terminal 4 on the OBD II J1962 diagnostic jack is Chassis ground.
Terminal 1 is Ignition Switched power.
Terminal 16 is Battery power.
Terminal 5 is a digital ground... This is the control modules logic reference ground not a chassis ground... there is a diffrerence. DO NOT test this terminal with ham handed equipment like a meter or test lamp.
Terminals 10, 6, & 14 are data lines. You can look for activity on these connections with an oscilloscope or a logic probe.

-Test from 16 to a body ground with your test lamp. The lamp should light.
-If 16 and body ground lights the test lamp test from 16 to 4.
-If the light doesn't light check the resistance from terminal 4 to a body ground with your meter then find and fix the damaged ground.
-If the light works then turn on the ignition and test from 4 to 1 with the test lamp. View attachment 162491
I had already done these tests, but when I tested key on power I only got 2 - 2.2 volts, so I suspected corroded terminals somewhere and proceeded to check at the ecu/cm area, where I found this
162516
6B4BFBED-B17C-42AC-BBCE-D0C7BC193AB6.jpeg

6B4BFBED-B17C-42AC-BBCE-D0C7BC193AB6.jpeg
6B4BFBED-B17C-42AC-BBCE-D0C7BC193AB6.jpeg
7C7BF2CC-9F3B-4122-9B82-049034A4F05B.jpeg
6B4BFBED-B17C-42AC-BBCE-D0C7BC193AB6.jpeg
7C7BF2CC-9F3B-4122-9B82-049034A4F05B.jpeg
The joys of living in the sticks.....

Sorry if this comes out goofy but it’s my fourth stab at this reply and I hope it goes through.
 

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Those little bastards carry Hanta Virus and they pee and crap everywhere they go.
That's nothing to fool around with. Wear gloves and wash it out with Clorox and water.
 

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I had already done these tests, but when I tested key on power I only got 2 - 2.2 volts, so I suspected corroded terminals somewhere and proceeded to check at the ecu/cm area, where I found this
View attachment 162516 View attachment 162516

View attachment 162516
View attachment 162516
View attachment 162517
View attachment 162516
View attachment 162517
The joys of living in the sticks.....

Sorry if this comes out goofy but it’s my fourth stab at this reply and I hope it goes through.
Where is this picture taken from? I have an 08 SS and have had the same kind of thing going on for the last 2 weeks. Started out having the battery dead, jumped it and it started fine. I thought it was a fluke. Couple days later it died on me while it was running. The service brake assist light came on. Service stabilitrak light as well. Jump started it again and figured it was the alternator. So my dumb ass ordered a remanufactured one. Had the battery tested and it was at 97%. Changed out the alternator and serpentine belt. Was fine yesterday. Today on my way to work everything went goofy again. All the service lights came on. Door locks started locking and unlocking. I pushed it out of the way and tried to jump start it. Then I noticed the new alternator smoking. So I left it and came to work. Any guesses?
 

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Discussion Starter #10
Where is this picture taken from? I have an 08 SS and have had the same kind of thing going on for the last 2 weeks. Started out having the battery dead, jumped it and it started fine. I thought it was a fluke. Couple days later it died on me while it was running. The service brake assist light came on. Service stabilitrak light as well. Jump started it again and figured it was the alternator. So my dumb ass ordered a remanufactured one. Had the battery tested and it was at 97%. Changed out the alternator and serpentine belt. Was fine yesterday. Today on my way to work everything went goofy again. All the service lights came on. Door locks started locking and unlocking. I pushed it out of the way and tried to jump start it. Then I noticed the new alternator smoking. So I left it and came to work. Any guesses?
You don’t have my problem.
Transmission control harness was chewed by rodents, car would not start, yours runs (intermittently?)
Sounds like you could have a short or bad connection in a harness somewhere or bad grounds.
Good luck with the repair.
 

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You don’t have my problem.
Transmission control harness was chewed by rodents, car would not start, yours runs (intermittently?)
Sounds like you could have a short or bad connection in a harness somewhere or bad grounds.
Good luck with the repair.
I replaced the alternator, serpentine belt and battery and now the car starts fine. But my steering is off. The car feels loose and the steering wheel is always at an angle to go straight
 

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You may need to calibrate the Steering Angle Sensor.
You need a Tech 2 or Autel Maixisys or Snap On Verus or another bi-directional diag tool on that level of sophistication.
Of those three the Chinese knock off Tech 2 is cheapest at around $250-$350 and it does more on your 08 GM. The 2013 model year is where the Tech 2 completely stops being useful. It's probably more like 2011 or so because the last few years are neutered. I have a handful of earlier software revisions burned to flash cards. These revs give me more functionality on the older vehicles back to 1991/92 ish and less on the newer.
By 2010 ish GM was putting more development into the Daily/Monthly/Yearly subscription GDS software coupled with the Bosch built MDI interface hardware than updates for the Tech 2 with updates that don't expire.
Just a way to keep the unwashed masses from repairing their own vehicles while appearing to comply with Magnusson Moss and other similar legislation. GM can extract $ from you even if you refuse to use thier woefully inadequate dealer service departments. Ummm... I mean Dealership parts changers.:rolleyes:
 
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You may need to calibrate the Steering Angle Sensor.
You need a Tech 2 or Autel Maixisys or Snap On Verus or another bi-directional diag tool on that level of sophistication.
Of those three the Chinese knock off Tech 2 is cheapest at around $250-$350 and it does more on your 08 GM. The 2013 model year is where the Tech 2 completely stops being useful. It's probably more like 2011 or so because the last few years are neutered. I have a handful of earlier software revisions burned to flash cards. These revs give me more functionality on the older vehicles back to 1991/92 ish and less on the newer.
By 2010 ish GM was putting more development into the Daily/Monthly/Yearly subscription GDS software coupled with the Bosch built MDI interface hardware than updates for the Tech 2 with updates that don't expire.
Just a way to keep the unwashed masses from repairing their own vehicles while appearing to comply with Magnusson Moss and other similar legislation. GM can extract $ from you even if you refuse to use thier woefully inadequate dealer service departments. Ummm... I mean Dealership parts changers.:rolleyes:
They have hydraulic power steering, not electric
 

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Yes it is hydraulic assist. However, the electronic stability control systems (ESC) like Stabilitrak can actually influence vehicle steering to some degree.
Some ESC systems more than others but that is the job of ESC.
It's far more noticeable in the Gen 9 Impala and the K25 chassis SUV and Pickups and even newer models that have lane control but it is noticeable when the SAS calibration gets out of whack on slightly older vehicles like ours that have earlier embryonic versions of ESC as well.


You might be noticing a mechanical fault that slowly crept up on you and you just plain got used to but was there all along. Some time in the driver seat of a car in better shape has made it glaringly obvious that something ain't right with your machine.
I would recommend that you check tire inflation, tie rod ends, ball joints, control arm bushings, etc.
 
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