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Discussion Starter · #1 ·
Especially when going over a bump, the radio and windows will lose power. The windows will stop working and the radio flickering on and off. Seems like a loose wire to me, causing a short. Does anyone know which wire would likely be the culprit affecting both radio and windows at the same time? :smilie_help:
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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The power windows and audio system are fed power through the "Retained Accessory Power" (RAP) module that has been incorporated into the Body Control Module (BCM) from 96 and up. The BCM is notorious for stress on the terminals that cause intermittent (or permanent) breaks in the circuit. I believe GaryDoug has posted a "how to" for resoldering the BCM contacts that cause this problem. Let me see if I can find it.
 
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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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Ramblin' Wreck
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I'm not familiar with any test procedure for this. But I would just open and drop the front of the glove box, turn on the radio, and tap and/or push on the BCM to see if that causes the radio to silence.

Push in on both sides of the glove box to open it fully past the stops. To put it back just push the glove box inward.

Automotive tire Motor vehicle Tire Bumper Automotive exterior Automotive tire Motor vehicle Automotive exterior Bumper Steering part
 

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Discussion Starter · #6 ·
Thank you guys for helping. I have diagnosed the BCM by tapping on it, and I have acquired all the materials I need to attempt this repair. Can you please tell me if removing the BCM will cause the car to be inoperable, or will it still run and drive without the BCM?
 

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Ramblin' Wreck
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The engine won't start without the BCM connected, but you can always plug in the cables and leave it hanging under the glove box.

Once the BCM is out, it should only take a few minutes to repair.
 

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My question is; did you buy a new or used bcm? If you bought a new one, it will program itself to your ignition key when you turn ignition on.

If you bought a used one, it is already programed to 1 of 15 key resistor pellet values. So unless you are very luck and have the same key pellet resistance as your old bcm, vats security will prevent starter and fuel injectors from operating.

But alas, there is a cure. You can get the lock cylinder from the car you got bcm from. Install it and all will be golden.

Or you can find out which resistor value your new used bcm needs and install that resistor value. Car will be good again. Here's where to go to read up on vats and installing the resistors.http://www.shbox.com

#'s 25 , 26 , & 27 in the how to section. Even though info is geared to lt1 models, it is still good for ls1 cars.

Also download the 2000 service manual. It will have wiring diagrams, component location views, etc. There's a link to it in the 4th gen tech section.
 

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Ramblin' Wreck
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I think he is repairing it, not replacing it.
 

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Discussion Starter · #11 ·
Correct, I am pulling out the original BCM to repair it. I was just wondering if this is likely to work out ok for me. In other words, on a level 1-10, what is the difficulty of this repair, or the likelihood it will work out ok?
 

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Ramblin' Wreck
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The success rate of this repair, if done properly, is nearly 100% as this is a well-known problem. The biggest problem for me was in pulling out the BCM from below. It is snapped into the holder and there is almost no wiggle room to move it around. Getting it back is almost as difficult. Patience and some trial and error is essential here. Remove the long kick panel first for the easiest results but take care to not break the panel.

Use static control, to minimize the chance of your generating a damaging static spark, by laying the BCM circuit board onto a sheet of aluminum foil which is somehow already connected to a ground. A metal water faucet/sink or the center screw of an electrical outlet cover plate are good grounds. If your soldering iron has a 3-wire plug, the heating element is a good ground and you can briefly touch it using a screwdriver so as to avoid burns,, Frequently touch your hands to the foil in order to drain off any static from your body before touching the circuit board. I mention all this because of the dry conditions that go along with the winter season.

If you can use the soldering iron, even minimally, this repair is easy. You are just melting the existing solder at the 5 locations to allow it to cool and reform without the crack(s).
 

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Very glad I found this post. I currently have the same issues with my 2000. It coincided with a stereo install so I keep second guessing myself. Over the past week I have been thinking more about the BCM. Thank you all very much for the great info. You guys rock!!! I will let you all know when I get it fixed. Might be a couple weeks tho.
 
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