NEED HELP Electrical gremlins

[Denis]

We recently purchased a 2008 trailblazer (history unknown). First noticed that only one front passenger side speaker was working, then noticed that the 4x4 selector switch would only select 2wd. Then the dome lights would not extinguish and finally dash lights have gone crazy several times. (once while exercising the shifter - and another time while driving). Then every thing started to work - sound from all speakers, dome light and ajar indicator working. As I drove up our driveway and hit a small bump - everything went blank. After turning the truck off and let it sit for awhile - everything is working again.... (no engine warning or chk engine lights are on right now) although the intrusion indicator has come on and off.

The rear wipers also are not working nor is the rear washer pump. The wiper select switch rotates but doesn't appear to be doing anything.

I did replace the 4x4 selector switch with a new unit - same problem. This truck is equipped with remote entry - we did not get any fobs so I do not know if this feature works.

Just need a little guidance as to where to look first or what to check first.. Thanks

 

[Sparky]

Generally if there are electrical gremlins, the first thing to do (because it is pretty easy and cheap) is the ignition switch.

 

[Denis]

Yep, Thanks.. The ignition switch is touchy.. That will be the first thing.

 

[xavierny25]

Welcome to the nation!!!!

There's a common ground on the passenger side between the glove box and floor but closer to the shifter area. Have a look and check if it's clean and tight.
The ignition switch has done that to my brother-in-law in the past when hitting bumps. Might aswell grab one since there cheap and are a known to cause issues.
Good luck and welcome aboard.

Edit: damn @Sparky your fast.

 

[Denis]

Yep, I replaced the starter switch and that did solve some of my problems.. Thanks for that one. I will check the ground as you suggested.

Now, I have a rear hatch that is not working. The rear wipers are not working either. And I do not hear the rear washer pump working.

Any suggestion??

 

[Sparky]

Check the wires in the boot going to the rear hatch. Sometimes one breaks in the insulation and can cause stuff back there to not work.

The rear pump though is still up front, in the washer reservoir next to the front washer pump. Swap the electrical connectors and see if the rear washer switch causes the front to spray after the swap, and/or if the front washer switch causes the rear to spray. This will help narrow down if it is a power feed issue to the pump, or a pump failure itself.

 

[Denis]

Unfortunately, the original symptoms are back - everything worked after replacing the switch - now as I drove down the road the dash lights came on the radio went out - Once home I turn key off / on now lights are out, however the radio is playing though one speaker (original symptom).

I removed the module in the box behind the drivers seat. Pulled all the connectors and cleaned with contact cleaner ( have done this several times) - nothing seems to change.. Ordered another module from ebay to help troubleshoot - have to wait as we are leaving town for a week.. If the module doesn't work it will be heat gun and cool spray and wire pulls

I did notice that the little solenoid near the ignition lock and cylinder was warm to hot during the switch replacement - do not know if this is normal?

So, until next time thanks for the guidance..

 

[Mooseman]

Did you check the grounds? This thread has all the locations:
Electrical Ground locations

 

[SpeedUp]

How old is the battery? Might be time for a new one

 

[Denis]

You said: Check the wires in the boot going to the rear hatch. Sometimes one breaks in the insulation and can cause stuff back there to not work.
I did find two (2) wires broken in the rear hatch in the boot.. Now the read door latch and wiper / pump are working - I think that some of the initial troubles were caused by the wires shorting.

Still have the 4x4 switch troubles! Tried replacing the 4x4 switch and the T-Case ECU with another unit.. Same issues: switch lights flash but then extinguish. I can hear a servo sound when I switch the switch.

Replaced Front Axle Disconnect Actuator Switch with a new unit - still the same problems.

The battery looks to be a newer battery - no corrosion on the terminals, fairly clear overall. I did disconnect the negative terminal for about 15 minutes - This was suggested by a local chevy dealer - same troubles..

[Mod edit: Please edit your last post instead of posting consecutively. Thanks.]

 

[JimInRadfordVA]

I had weird gremlins on my 2005 TB I-6. Would get random rear wiper sweeps and occasional no crank issues. Turned out to be a loose battery cable.

Clean and tighten both battery posts. Check the grounds, as listed above. Check the main harness connection from the battery. Your problem lies somewhere in there or the ignition switch.