Multiple simultaneous electrical failures

2003 Silverado
4.8L
Manual Transmission / Manual 4wd


Posting for a friend: About a week ago, he got into his truck and started it to find the following:

ABS light on solid
Check Engine light on
HVAC controls (manual) no longer work, stuck on full hot w/no fan at all
4wd no longer working
Cruise control not working

Nothing happenned that corresponded to these failures; when he drove to work that morning, everything was fine. When he came out that afternoon and started the truck, this happened.

Right now, the only code that shows is P0704, which is the clutch switch input circuit. However, he has not had any ABS or Transmission codes pulled yet so there may be more that we're not aware of.

We are just now starting to look into this today and are going to check as much as possible before turning it over to the dealer. We are going to start with the obvious such as bad grounds and bad connections at the various modules and connectors and then go from there.

Has anyone here ever run into anything like this before?

Thanks.

2003 Silverado
4.8L
Manual Transmission / Manual 4wd


Posting for a friend: About a week ago, he got into his truck and started it to find the following:

ABS light on solid
Check Engine light on
HVAC controls (manual) no longer work, stuck on full hot w/no fan at all
4wd no longer working
Cruise control not working

Nothing happenned that corresponded to these failures; when he drove to work that morning, everything was fine. When he came out that afternoon and started the truck, this happened.

Right now, the only code that shows is P0704, which is the clutch switch input circuit. However, he has not had any ABS or Transmission codes pulled yet so there may be more that we're not aware of.

We are just now starting to look into this today and are going to check as much as possible before turning it over to the dealer. We are going to start with the obvious such as bad grounds and bad connections at the various modules and connectors and then go from there.

Has anyone here ever run into anything like this before?

Thanks.

check all fuses with meter then with voltmeter check for power with engine running to find what circuit lost power....could be bad ignition switch...or wire /feed off of switch/ground....


if ground is lost that will make it harder...


dealer will be expensive in most cases so don't give up easy..

2003 Silverado
4.8L
Manual Transmission / Manual 4wd

ABS light on solid
Check Engine light on
HVAC controls (manual) no longer work, stuck on full hot w/no fan at all
4wd no longer working
Cruise control not working

Nothing happenned that corresponded to these failures; when he drove to work that morning, everything was fine. When he came out that afternoon and started the truck, this happened.

Right now, the only code that shows is P0704, which is the clutch switch input circuit. However, he has not had any ABS or Transmission codes pulled yet so there may be more that we're not aware of.


I'm the owner of said truck and in addition to the above, it's a manual trans and the upshift light no longer functions. All dome lights, guages, stereo, horn, etc. is still working. I haven't found anything other than what's listed above to not be working.
About a month or so ago, I did notice the tach started reading about 1000 rpm too high for about 2 or 3 minutes. This has not reoccured since then.
I've checked the fuses and ground points at G200 and G203. We're very quickly moving into the area at which I'm completely confused and can do nothing but sit around with a "divide by zero" look on my face.

I did disconnect the battery cables hoping to reset codes, but everything returned as it was (error states) instantly.

Please help!!!! I'll send beer!!!

Rodents?

Bad PCM?

I have a strange one too where I get bad misfires only when it rains. Thought I had it fixed but it came back in the last storm.

...good luck...

Rodents?

My first thought as well.

Look under the fuse box in the engine compartment and see if there's missing insulation anywhere.