H3 Weird computer issues.

[ponchoV8]

My '09 H3 is exhibiting some weird computer gremlins. If it has been sitting unused a while, after start-up the display center in the dash flashes stability control, 4wd and brake malfunctions. In addition, the a/c will shut off and the power windows will quit working. The truck still runs fine, brakes work normal, 4wd engages hi-lock to low-lock; just the a/c and windows stop working and all these dash lights flash and do not go away unless I disconnect the battery for a time. The problem disappears then eventually the same issue pop up again at start-up. I've cleaned the battery terminals and my engine is unmodded except for a K&N filter and Sherpa snorkel. It has been raining a lot here in FL, perhaps a connector of some kind is corroded? Any advice much appreciated. Thanks.

 

[Happy Hummer]

Hi poncho

Have you removed the oem battery connectors?
Also how old is your battery?

Chris

 

[Steve #1]

Agreed, sounds like battery, battery terminals or a ground issue.

 

[ponchoV8]

The battery is still the one that came with the truck when I bought it in '11. The terminals are still in decent shape but unless I coat it with dielectric grease they tend to corrode quickly. Perhaps you guys are right. My '02 Trans Am started having weird electronic issues then the battery died. Replaced the battery and everything was ok. I'll have the battery tested, thanks. Are the battery terminals an issue on H3's?

 

[Bigunit]

YES, a big and common issue. Replace those first and report back to let us know if the issue has gone away.

 

[ponchoV8]

Went through all the external chassis grounds. Found the main negative ground from the battery to the engine block was loose; compared to all the other grounds this one was loosened with barely a flick of the wrench. I went through all the external grounds and cleaned them off with sandpaper and added some dielectric grease prior to bolting them back on. No intermittent dash lights since then. I did buy new Tsunami terminals and will be installing those this weekend. But so far the grounds suggestion has held true. Much appreciated.

 

[Happy Hummer]

Great news.

 

[Renagade132]

Good to hear it worked out!