Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 6 of 6 Posts

·
Registered
2002 chevy trailblazer_ls
Joined
·
9 Posts
Discussion Starter #1
Have the dreaded 4WD service light on, and have read posts that say to check #8 fuse underhood;which is appreciated.
My haynes manual showed this circuit for selector switch feed coming off of the underseat fuse box, and was on a common feed with headlight switch.

Find that unbelievable, so am asking if anyone can post or email the correct schematic?

Thanks
 

·
Banned
2004 gmc
Joined
·
26,181 Posts
That Haynes connection might be just for the dimmable instrument panel lamp feed, so the selector switch lights will dim with the rest of them.

Anyway, this system's my specialty. What's the maintenance history of your vehicle, if any? Do you regularly exercise the 4WD system?

Don't just check the fuse - pull it for 30 seconds to reset the TCCM, then turn the ignition on but don't start the engine. Move the selector switch to A4WD and see if you hear two different motor noises. One high pitched for 3-4 seconds, and the other lower pitched for 1-2 seconds. If you do that, does the service 4WD light come on?

2002 had an issue of some bad TCCMs that need to be replaced. They can also be helped by a flash update from the dealer, if the TCCM hardware is OK. The indicator of these problems is a TCCM that doesn't want to wake up and talk on the data bus to the rest of the vehicle after you turn on the ignition. To conform this diagnosis, you can turn on the ignition, THEN go and pull underhood fuse #8 for 30 seconds, then plug it back in (it's safe to do this with the ignition on) and then move the selector switch and see if it works OK. You don't have to replace the TCCM in this case, as long as you know you have to go under the hood whenever you want to change 4WD modes. Annoying, but can save a lot of $$ if you only rarely ever use the 4WD system.
 

·
Registered
Joined
·
1 Posts
is there anyway to bypass the switch and all the other BS and just wire hi and lo onto toggle switches
 
1 - 6 of 6 Posts
Top