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?