vent fan, 4x4 selector, ABS all at once!

[mister moose]

First was the 4x4 control, it started with no 4WD low, and then shortly after no 4WD at all. Had a mechanic look at it, diagnosed the module and recommended I swap it out. I checked the fuse, and discovered the 4wd would work once if the fuse was pulled, as if it reset something. Then no additional function after the reset.

I got a used module and it didn't work at all. However, while removing the module mount screws, the vent fan turns on, all by itself. Key wasn't on. I swapped out the fan relay and it still does it.

And then the next time I drove it the ABS light comes on. And then this mystery beep comes from behind the radio while driving, different that the key reminder or seat belt chime. It's a fairly long 1.5 second be-e-e-e-e-p

I'm up in snow country and need the 4WD. Really need it. I'll order a new module, but wanted some opinions first:

Are these events related or coincidental? I'm thinking they aren't related, but it's worth asking.

Any other reason the 4WD doesn't work? The lights come on properly (once) after the reset. The mechanic said the actuator in the txfr case was ok.

What else can I check on this obnoxious vent fan? Yes, I can turn it off by selecting the off position, but if I forget to do that it's going to be dead battery in the morning.

I'm begining to think I'm in some electrical bad karma zone.

thanks.

 

[black_demon69]

sounds like a short or bad ground to me

i would get a wiring diagram of affected systems and start tracing the circuits

 

[Earl43P]

In 2000, all those systems used Ground 103, located on the top center of the LH fender apron. Might try cleaning that ground up.

Heater relay has to have key in Run to energize, so it really messes with my electrician mind how that is happening. 02 may differ from these 2000 EVTM schematics though.