Author Topic: Service 4wd Light on, 03 Chevy Trailblazer  (Read 5189 times)

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Service 4wd Light on, 03 Chevy Trailblazer
« on: October 10, 2008, 04:31:42 AM »
Drove to work yesterday morning, and my Service 4wd light came on.  Also, on the switch where you turn to swith between 2wd and 4wd usually has an indicator light to show what one it's in was off.  Truck drove fine.  I was in 2wd at the time, have never had it in 4wd yet.  But with winter coming on, I'll be needing it soon.  Then when I went home, the light was off and the indicator light is now working.

I will be going to my mechanic on Saturday and he is going to scan it to see if we could pull up any codes, but was wondering if anyone had any ideas.  I did some research on the net and found some that were having problems with some type of switch. Other's solved the problem by pulling number 8 fuse, though I don't see how that will "fix" the problem if there is one.  I'll post codes if it gives us any.

Linkback: http://www.trustmymechanic.com/forum/b1/service-4wd-light-on-03-chevy-trailblazer/18496/

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discretesignals

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Re: Service 4wd Light on, 03 Chevy Trailblazer
« Reply #1 on: October 10, 2008, 07:56:04 PM »
There are two known problems with your symptoms and both of them require having the TCCM(transfer case control module) reflashed with the latest calibration.

I suggest that you drive down to the dealer or a shop that has the capabilities of flashing the TCCM and have it updated before doing any other diagnosis.  More than likely it is a software issue causing your concern.

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Re: Service 4wd Light on, 03 Chevy Trailblazer
« Reply #2 on: October 11, 2008, 11:23:56 AM »
We hooked up his Genisis 3.0 scan tool and came up with U1000 code.  Which is basically a generic code and does not specify very much.  Came up something like "No health at modulator".  We read the snapshot at the time the light came on, and everything looked normal.  Light came on at .06 seconds after starting truck (already warm).  Nothing seemed out of wack.  We left the code in history.  Called the dealer, and they will preform the reflashing according to a known TSB for nothing.  Also, they want to take a look at some sort of wiring harness, seeing how it was raining at the time it came on and they know of some problems with rain getting on some wire and causing similar problems.  After the reflash, they will hook back up to the computer and try communicating with the module to make sure no other codes are being given out.

Man, I spent an hour or so with my mechanic going over all the things that scan tool can do.  All the different sensors it can communicate with.  I was simply amazed!!!  Even my power seats have a sensor on it!!  

Light hasn't come on since that one time.  Maybe just a flook, but want to make sure before snow comes and can't use 4wd.

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