been trying to troubleshoot the rear defrost issue on my '03 3800 impala. connections all look good at window, at breaker box...relays and fuses both under hood and under dash look good..checked the "hidden| glove box 30amp breaker behind the junction box as outlined by the Maniac in repair guide section and the breaker is good. dont appear to be getting power at rear window terminal...any other ideas i can check? not sure if its related but the stereo is not getting power either. ... read something on another forum about a ground wire in the trunk area...???

dave

 

I don't believe power to the stereo and the defroster are related (but I won't say 100%). Here are some thoughts (and you may have covered them already):
- When you hit the rear defroster, do you hear the relay click?
- Even though you went over the circuit breaker, do you know if you are getting power passing through the circuit breaker when you turn on the rear defroster?

Next, the Montes and the Impalas of this era, they have a box hidden behind the rear passenger side trim that controls signaling between the defroster and the radio antenna in the glass. That is the next spot to check. You have to pop off the rear interior quarter trim and follow the wire from the glass to the box. It's a dealer part to replace and I've heard there are two different part numbers for it (so you have to get the old one out first). I'd check if you are getting power to that box. If so and there is no power to the glass, I think that box is bad. Now, in a world of uneducated hypotheticals, if that box failed, I wonder if it allowed voltage to go back to the radio via the radio antenna and popped the radio. One way to check, pull the radio and see if you are getting power at the harness.

 

Is that the "radio antennae module?" I've read a little about this...where you exactly am I looking?

 

I believe that's what it's called.
To find it, you need to pop off the plastic trim on the back passenger upper quarter (if you look were the rear speaker desk is, the trim on the passenger side that comes down to that, you have to pull it off).

My wife has an '05 Impala and I pulled that trim off when installing a Driver Info Center (to get access to the wiring harness under the speaker deck). I am not sure of the rear seat has to come out to get the trim safely out or not (I don't think it has to). Double check for screws/bolts, but I don't think there are any, I'm pretty sure a couple careful tugs and it pulls out.

 

why did you say dealer only part. i tried a search and weirdly.. rock auto and few others have the module listed for the 05 supercharged motor only. acdelco part 10399641

ACDelco 10399641 Radio Antenna Module

wouldnt it be the same for 00-05

 

When i was chasing defroster issues, the only place I could find with that module was the dealer. Apparently things have changed since then.
That sounds like the right item.

 

maniac---

is this easy to remove and re-install....i think im going to replace that module.

 

ok, i located the module. it is actually on the drivers side. anyway, i have limited electrical knowledge. i have a dc voltmeter... how exactly can i test that power is getting to or out of this area?

 

Easiest test is using a test light. The test light needs one end connected to ground and then the probe contacts to a point you want to test. If it has power the light turns on.

I would test the wire going into that box, verify power is getting to the box that way.

 

i dont currently have a test light but when i checked the connector clips at the window a few weeks ago with the test light it indicated no power. would my assumption most likely still point to a bad module?