XPTB

iTrader: (1)

Hey,

My HU keeps cutting off and on by itself randomly while I drive. It was completely stock then I replaced it with an aftermarket HU... still stock speakers though. The aftermarket one does it also.

To make this odd, my power windows also will not work when the HU cuts off. My door locks work fine, just the power windows. Does anyone know if the HU and the power windows meet somewhere in the wiring? Anyone ever heard of this before?

Thanks.

XPTB

iTrader: (1)

I bought a haynes manual and I can't find anywhere in the wiring diagrams that the power windows and HU meet.

Anyone know?

jm4designs

I believe they are connected through the R.A.P. (Retained Accessory Power) circuit, and I'm pretty sure there's another thread on here about this problem. (pretty common) Not sure if there is a fix or not yet for it. I'm actually downloading wiring diagrams as we speak to try and figure something out.

XPTB

iTrader: (1)

Thanks for the info. I did some searching on the RAP and found that it's related to the BCM and that it usually needs to be replaced if its not something simple like a loose wire or dirty door open sensors.

rmpitzer

iTrader: (5)

Yup, replacing the BCM fixed the radio and window problem in my car.

XPTB

iTrader: (1)

Was this complicated to do by yourself? Did you have to let GM flash it? I heard the BCM controls your ignition security deal.

rmpitzer

iTrader: (5)

I have the factory service manual, and followed the procedure to install it. But, basically, you unplug the old one, plug in the new one, and turn on the car. The first use programs the BCM for your key pellet.

At least that was the procedure for my 97. Not sure if anything may have changed in later years.

-Rich

mattgofaster

how much does a new bcm cost? my radio and windows do the same thing.

slow

iTrader: (7)

the headunit (radio fuse) and the power windows share the same circuit going into the fuse box.

Ryan

rmpitzer

iTrader: (5)

It was a little over $200 from my local Pontiac parts department.

SSNixon

Can you buy any BCM from any LS1 F-body? In other words, I have a 2000 SS with a M6. Can I buy a used one off of a 01 z28 with an A4 tranny?

rmpitzer

iTrader: (5)

Well, there were a few different BCMs (one with keyless entry, one with the alarm, etc).....but more importantly, if you are thinking about trying a used one, it has to match the resistor in your key. If you buy a new one, the first time you use it, it programs itself to match your key.

SSucese

iTrader: (1)

I just happened to stumble across this thread being that just in the last week my SS is experiencing the exact same problems. Now forgive me for asking but what does BCM stand for and where exactly is it located at? Before I did a search on this problem I was thinking it had something to do with my power antenna i just installed on the car being that everytime it happened the antenna went down but what I did not notice was that the whole radio and windows(as mentioned above) all would not work from time to time. Any more info is greatly appreciated!!

rmpitzer

iTrader: (5)

BCM is the Body Control Module. They started using them in 96 or 97? Before that, I hear the cars had a seperate RAP module (Retained Accessory Power....the system that gives the radio and power windows power after shutting off the ignition). In cars with a BCM, the RAP system is part of the BCM.

The BCM on my 97 TA was located behind the dash, on the passenger side, directly behind the glove box.

I can't emphasize enough to follow the diagnostic procedure in the factory service manual before replacing the BCM. I've heard people fixed the intermittent radio problem by wiggling connectors, or tightening grounds. I wasn't so lucky, after following the diagnostics, it pointed to the BCM (about $250 for a new one). If your problem is something other than the BCM, spending $250 for nothing would not make you happy.

-Rich

SSucese

iTrader: (1)

I ended up taking the advice of others on here and checked the wiring going to the BCM the other night. What I found about a minute upon troubleshooting was everytime I shook or grabed the wires going in to the BCM I was able to recreate my orginal problem with the HU going out along with my power windows. It did look like one of the pins was not secure and I proceeded to uplug the harness fix the pin and so far (cross my fingers) everything has been good since.

Phil8616

iTrader: (11)

I'm having the same problems, I want to check the BCM wires as well. You have to pull the glove box out and the BCM will be behind that? There isnt a picture or step to get to it is there? Or is it pretty self explanatory? Thanks

SSucese

iTrader: (1)

Well crap, I thought I had mine all fixed and then today right when I step in to my car after a long day of work I noticed the radio and windows are a no go But yeah its located right under the glove box on the right side. Funny thing was I left the underside of the dash off because I had a feeling this might come back and haunt me so I again found myself shaking the wire harness while driving the car just so I could get some tunes on the way home from work I have a strong feeling however something is still loose because on the drive home I noticed that everytime the HU loss power i had just went over a bump in the road however, I dont understand why in the hell this is all happening all of the sudden?? Its not like I was every underneath that area of the inside of the car dicking around with the wiring or anything so it leaves me puzzled Lemme know if you find out anything else on yours as I might end up having to take a closer look at it this weekened

Phil8616

iTrader: (11)

Yeah, ill be spending Saturday morning trying to fix this problem and a few other electrical related problems...we just need to all get together and bring some cold beer and brainstorm.. ..hopefully the solution is fixing a short or the BCM like stated above.

rmpitzer

iTrader: (5)

This same exact thing happened with my car. I thought I had it figured out, a loose connector. When I wiggled it, it would cut out. I tightened up the connector and it worked fine for a little bit, then went back to cutting out, like you state, usually when going over a bump. I was convinced it was wiring, and did more wiggling, and at one point, wiggled the BCM itself (after removing it from it's mount).....well, when I did that, something sparked inside it, and it smoked. After that, I had no power door locks, no interior lights, no radio, or power windows. At that point, I was pretty sure it was the BCM itself.

Buying and installing a new BCM fixed it all, and everything has been working fine for a year now.

-Rich

Phil8616

iTrader: (11)

Whered you get your BCM by chance? Dealership? Price?