Weird Electrical Issues - 2003 Z71 Sub

[Houston54]

I have a 03 Z71 suburban which currently has 81K on it. Other than the gauge cluster being swapped out at 50K and a new fuel pump/filter at 58K it has been a good vehicle.

However I recently have been experiencing weird electrical issues which I cannot nail down a cause for.

The problem is intermittent though which complicates a diagnoses. I hope someone has some suggestions or has solved this issue already.

It includes the dash lights, chimes and door locks cycling as you are driving. The first time it happened I took it to my mechanic and he pulled two sheets of codes off the ecm. Since it was damn near impossible to get a direct replacement ecu that matched for some reason we wiped the old unit clear and reprogrammed it. This mitigated the problem but did not solve it.

At intermitate times the chimes will sound, the cruise control will become inop, the ABS dash light and parking brake light will come on and stay on. The message center will say to service brake system, check washer fluid and sometimes check 4wd. If you shut the ignition off and restart it will reset everything until the next occurence.

It seems that most often than not, but not always, the issue happens when you go over a large bridge transition, bump or expansion joint.

I have pulled the battery cables and cleaned them, I have checked all ground connections I can locate and the problem persists.

Has anyone else experienced this or can some suggest a cure?

[Huck]

Check for mice nest --chewing the wiring under the main fuse box under the hood. Buddy had similar problems that the dealer couldn't find easily. His insurance company paid for all the damage repair.

[redneckgirl]

My 03 Denali has strange electrical issues happening right now too, but not the same ones you have.
Radio ocassionally not having sound, driver's side seat heater not working (comes on, then shuts off whenever it feels like it) Radio still playing when the CD Changer is in use (that's kinda freaky to hear two songs at once ) door lock issues sporatically, etc...Maybe I'll be checking for a critter nest as well...

[Houston54]

My problems with the electrical issues continues.

I pulled the battery out and had it tested at the local parts house. It tested as being good but only had 4% of its charge. They charged it up and it tested out fine. I reinstalled it but the truck will not start now. The starter is not working and the security symbol is on constantly. I have tried the reset procedure with no success. I decided to let it sit overnight to see if it would time out.

This morning the battery was almost dead again. I swapped in another battery I had with no success either.

Has anyone had a continous battery drain before? I confirmed all the accessories and lights are off.

[truckdude239]

bad alternator will cause a battery drain. try taking your keyless thingy lock the doors and then unlock the doors and try to start

[Houston54]

Thanks for the tips but that has been tried. Also tried unlocking the passenger side door manually.

Anyway the key fob routine will only work if you have power and the battery is drained.

Going to focus on the BCM in the morning if I can find it.

[Houston54]

After researching this problem on the web over a couple of days I determined there were many other 2003 Suburban/Tahoe/Pickup owners out there with this same problem.

I also found there is a recall notice for a battery drain issue which I was also experiencing. Unfortunately my VIN was not within the recall scope. For anyone else who may be having a battery drain issue with their 2003 you might want to check to see if your VIN is covered by recall notice 02066.

As to the other problems I was experiencing I came across another owner who was having the same problem with the chimes sounding, dash lights flashing, cruise control going inop, and door locks cycling. He had tried the dealer for a solution with no success. He then ran down all the ground connections on his Tahoe and found one wire loose. He reconnected this ground to a more positive position (the braided ground strap) and the problem went away.

I located this same wire on my 2003 Suburban Z71 and found it was intact. It appears to be a ground for the ignition system. To locate it you need to removed the plastic engine cover. Then, looking at the engine from the front, locate a black/yellow wire on the back left side coming out of the wiring harness. It is connected to the back of the engine block with a bolt. Disconnect this bolt and inspect the lug connection. Clean it and the block area and reconnect. You could also solder some additional wire to this lead and connect it to the ground strap located on the right rear of the engine.

I know this sounds too simple but it worked for this other owner and also for me. If you are having intermittent electrical issues with your 2003 you might want to try this.

If it solves the problem please reply here.

[killer71]

Thanks for the info. could you tell me why you had to change your speedo. cluster?