Electric issues with 4x4, fan & dash lights

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Hey All,
Looking for a bit of help on some electrical issues I'm having with my 2000 K2500 (has the 454 in it). Some of the dash warning lights started flickering on and off a while back (ABS/seatbelt/e-brake) but not a big deal. Truck still started and ran fine, then the ac blower fan would only work on High. Again no big deal, but now she won't shift from 2 to 4 wheel drive. I'm up in the mountains and slipping and sliding in 2wd in the snow sucks. Again, still fires right up and drive fine.
The battery was 9+ years old so I swap that out and cleaned the +/- wiring that connect to the battery. That didn't do the trick so started researching more and it sounds like maybe a bad ground somewhere? Does having all 3 of these issues at once indicate a specific ground I should look for? Also saw posts about an ignition switch possibly being the issue in some of these cases. It's below freezing out where I am so trying to get together a game plan before crawling under!
Thanks in advance for any help.
-Michael

 

[AK49BWL]

Classic grounding issue... Well, the blower issue could be entirely separate, but check the ground point above the OBDII port, make sure it's clean and tight. The cluster and 4x4 controller both ground there. The blower issue, could be your resistor blew out, but with everything else going on, definitely check the grounds first.

 

[Repstar]

Thanks for the suggestion Brandon. I found the ground above the OBD2 port and it looked like it was in good shape. I still disconnected it, cleaned it up and then reconnected it. Unfortunately still seeing the same issues with the dash warning lights, 4x4 and fan. Let me know if you have any other suggestions. Thanks again.

 

[sntrym]

There is also a ground from the rear of the passenger engine head to the firewall. I would check that one, and also the battery to engine ground just to be sure.

 

[Chevy-SS]

I totally concur with others - you've got a classic ground issue. There are a number of grounds spread around, look carefully at each one and clean them all thoroughly. If any doubt at all, replace the ground strap or main battery cable(s).

 

[Repstar]

Thanks all! I'll have a closer look later this week looking for voltage drops at the grounds once it gets above 14 degrees and stops snowing out there

 

[Repstar]

Update: The 4x4, dash warning lights & fan are all working again!

I rigged up my voltage meter on a long wire running from the positive battery terminal and went around testing the voltage drop. Battery was 12v, engine block was 12v, frame was 12v, firewall was 12v and the ground near the OBD port was 12v. So everything seemed good. Not knowing what to do next I had a look at the negative cable from the battery to the frame on the passenger's side and thought it looked pretty cruddy so I figured I'd at least clean it up even though the frame was reading 12v. After cleaning it all up to my surprise the 4x4, fan and dash lights were working again. Went for a test drive and fan on all speeds worked and I popped it in and out of 4wd at least 12 times with no issues.
So maybe the frame was grounded fine but the wire coming off the frame had some crud on it and that was the issue. Hopefully everything keeps working and this wasn't a coincidence.

Anyways thanks for the help!