2008 Avalanche LTZ Severe Electrical Issue

[ScienceMonkey]

I had looked at the following issue last year and thought that I had solved it, but it is recrruing again and I am at a loss.

 

The RPMs drop, the "Park Assist Off" display comes on, and the doors lock. When moving, the truck hitches a bit then resumes as normal. If at a stop, the truck stalls.

 

About every fifth occurrence, both the electronic and physical gas gauges drop to zero. The values increase over 10-15 minutes time if there is no reoccurrence, but immediately go back to accurate if there is a reoccurrence.

 

Last year, I replaced the 75amp mega (looked OK) and cleaned and reset the ground wire behind the driver's side tire. I have traced all of the visible wiring and haven't been able to locate any issues. All of the fuses appear intact.

 

I only put about 2,000 miles per year on the truck, and yesterday was the first occurrence since last fall. It was also the first warm day I have driven it in since then. The air conditioner was not on. Correlation doesn't equal causation and I have a very small sample size, but I just want to throw the temperature issue out there as additional information.

 

I have not been able to catch anything with my OBD reader and two dealerships have found nothing.

 

Any clues?

 

Thanks in advance,

SM

[Cosmic Charlie]

maybe the Body Control Module isn't right, they can reset themselves, and you can reset it by dis-connecting the battery for 20 minutes +-

 

its free to try

 

check out this BCM failure

 

 

 

Grounds ? ... OMG !

 

Expert: Dan replied 8 years ago.

This can be a very extensive list as there are several electrical systems involved and even though some share a ground there is still alot from front to rear.

G100

In the Forward Lamp Harness on the Lower Left of the Radiator Core Support

Power and Grounding Component Views in Wiring Systems

G101

In the Chassis Harness, left side of the engine near the generator

Power and Grounding Component Views in Wiring Systems

G102 - Except 4.3L

In the Engine Harness, on the left side of the engine block, #3 cylinder area, below the exhaust manifold

Power and Grounding Component Views in Wiring Systems

G102 - 4.3L

In the Engine Harness, Right Front of the Engine near the Crank Sensor.

Power and Grounding Component Views in Wiring Systems

G103 - Gas

In the Engine Harness, on the Left Rear of the Engine Block

Power and Grounding Component Views in Wiring Systems

G103 - Diesel

In the Engine Harness, on the Right Front of the Engine Block

Power and Grounding Component Views in Wiring Systems

G104 - 4.8, 5.3, 6.0L

In the Engine Harness, on the Left Rear of the Engine Block

Power and Grounding Component Views in Wiring Systems

G104 - 4.3 and 8.1L

In the Engine Harness, on the rear of the left Cylinder Head

Power and Grounding Component Views in Wiring Systems

G105

In the Main Battery Harness, Main Battery Ground on the Right Front of the Engine

Power and Grounding Component Views in Wiring Systems

G106

In the Main Battery Harness on the Right Side of the Engine

Power and Grounding Component Views in Wiring Systems

G108 - Diesel

In the Engine Harness on the left front of the Engine Block

Power and Grounding Component Views in Wiring Systems

G109 - Diesel

In the Engine Harness on the Right front of the Engine Block

Power and Grounding Component Views in Wiring Systems

G110

In the Chassis Harness on the frame to the rear of the left front tire.

Power and Grounding Component Views in Wiring Systems

G200

In the HVAC Harness, on the Right Side of the I/P Near the A-Pillar Below the I/P Top Cover

Power and Grounding Component Views in Wiring Systems

G203

In the I/P Harness, On the Left Side of the I/P Near the A-Pillar Below the I/P Top Cover

Power and Grounding Component Views in Wiring Systems

G302

In the Chassis Harness on the frame to the rear of the left front tire.

Power and Grounding Component Views in Wiring Systems

G304

In the Body Harness, Under the Passenger Seat

Power and Grounding Component Views in Wiring Systems

G305

In the Body Harness, Behind the Drivers Side B-Pillar Trim Near the Bottom

Power and Grounding Component Views in Wiring Systems

G306

In the Body Harness, Behind the Passengers Side B-Pillar Trim Near the Bottom

Power and Grounding Component Views in Wiring Systems

G390 (Crew Cab w/Rear Window Defog)

Defogger Grid Harness, Near C-Pillar

Power and Grounding Component Views in Wiring Systems

G401

In the Chassis Harness, On the Spare Tire Hoist Assembly

Power and Grounding Component Views in Wiring Systems

G402 (Export Only)

In the Chassis Harness, Near the Rear Bumper Assembly

Power and Grounding Component Views in Wiring Systems

G403

In the Chassis Harness, Near the Left Rear Body Mount

Power and Grounding Component Views in Wiring Systems

G410

In the Body Harness, Right Rear Interior of Vehicle Behind the Right Side Cargo Area Trim Panel

[ScienceMonkey]

I'll give it a shot and update thie afternoon.

 

Thanks for the idea. I'm kind of desperate at this point.

[ScienceMonkey]

All of the grounds have been checked an it's not a ground issue. I detached the battery for nearly an hour and it's not something where a simple reset can fix it.

 

There is a very strong correlation to outside temp. The event occrued seven times in a three mile trip on an 83 degree day. It didn't occur once on a similar trip on a 48 degree morning.

 

I have it with a pro with a great reputation now. if a solution is found, I'll update the thread.

[d250]

Could the cap and rotor be bad.

 

 

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[PhilB]

Check your battery and battery cables. There have been incidences where acid corrosion occurs inside the cables. As the temperature increases, it could cause separation within the cables.

 

As a side note, I bought a used Altima as a commuter car. Test drive was fine. Day after I purchased it, my wife was driving around and it started doing funky things including stalling. My dealer sent someone over to get it. Had to have it towed. Ended up being a bad battery.

 

Long story short, voltage fluctuations can cause weird things to happen.

[finn5033]

Check your battery and battery cables. There have been incidences where acid corrosion occurs inside the cables. As the temperature increases, it could cause separation within the cables.

 

As a side note, I bought a used Altima as a commuter car. Test drive was fine. Day after I purchased it, my wife was driving around and it started doing funky things including stalling. My dealer sent someone over to get it. Had to have it towed. Ended up being a bad battery.

 

Long story short, voltage fluctuations can cause weird things to happen.

I can attest to the battery thing as well. About 2 weeks after I picked up my current Silverado the wife and I went out to eat breakfast in the morning. When I started the truck to leave the restaurant the truck gauges and radio went nuts like nothing I have ever seen. I was thinking oh my I think the computer just fried or something because the battery had showed no indication it was bad at all. Sure enough I replaced the battery and everything was fine. It is amazing the issues that can be caused from the battery.

[dkjbama]

Could the cap and rotor be bad.

 

 

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No. Distributors haven't been used on GM trucks since before the turn of the century.

[ScienceMonkey]

SOLVED: Faulty ECM was replaced and the car has been performing without an issue, even in 80+ degree weather. The truck has been driven over 100 miles since the repair.

 

My pro had the same issues, but as with my experience, they ONLY occurred when the outside temp was above 70. There was never an issue when the temp dropped 70.

 

I felt better that he and the guys he works with had never seen the issue before. I was fortunate that the part still had a few weeks left on the warranty.

 

 

[Cosmic Charlie]

A car's electronic control module is the computer responsible for providing fuel to the engine and controlling the quality of the car's emissions. The ECM uses a microprocessor and software to analyze and respond to the input values from an array of sensors. An ECM is typically part of a larger system, with multiple modules that control everything from power steering to airbags, commonly called the car's computer