When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Does anyone know where to buy a new BCM? MInes all messed up and I don't want to attempt to fix it without having a replacement. I've looked on summit and google but nothing has turned up. If anyone knows where I could get one I would appreciate it.
What are the problems with your existing BCM? A lot of people tend to blame the BCM for all sorts of electrical issues - many of which aren't even related to it. You might be chasing a replacement part that isn't necessary. Other than the infamous solder joint problem with the RAP circuit (windows and radio cutting out), there is very little that commonly goes wrong with a BCM.
If you post the symptoms you're trying to fix, perhaps we can help with an easier solution.
What are the problems with your existing BCM? A lot of people tend to blame the BCM for all sorts of electrical issues - many of which aren't even related to it. You might be chasing a replacement part that isn't necessary. Other than the infamous solder joint problem with the RAP circuit (windows and radio cutting out), there is very little that commonly goes wrong with a BCM.
If you post the symptoms you're trying to fix, perhaps we can help with an easier solution.
The radio and power windows switch on and off. I can send power through the fuse to make them work. But then I have a wire sticking out. Also, the speakers stop working and the alarm goes off randomly.
The radio and windows cutting out intermittently is a symptom of the retained accessory power (RAP) circuit solder problem. That's easily fixed using the instructions in this thread: https://ls1tech.com/forums/general-m...blems-fix.html. The photos that were deleted by the original poster were replaced starting at post #185.
If the speakers are cutting out other than when the radio cuts off due to the RAP circuit problem then it has nothing to do with the BCM. The BCM is not connected to the stereo system in any way other than providing power to the radio head unit. It could be the Monsoon amp or its wiring. Firebird or Camaro? The amp powers all speakers in Camaros but not the tweeters in Firebirds so if you have a Firebird and all speakers cut out except the tweeters then you can be reasonably sure the amp is involved.
The alarm going off randomly is not directly related to the BCM... 99.9% of the time it's due to water getting in the shock sensor under the right quarter trim in front of the spare tire. You should unplug it (the alarm will still work except for impact detection) and confirm that the false alarms stop. Then you can either leave it unplugged if impact alarm is not important to you or you can buy an aftermarket replacement - there are several makes and models available that will work.
The radio and windows cutting out intermittently are a symptom of the retained accessory power (RAP) circuit solder problem. That's easily fixed using the instructions in this thread: https://ls1tech.com/forums/general-m...blems-fix.html. The photos that were deleted by the original poster were replaced starting at post #185.
If the speakers are cutting out other than when the radio cuts off due to the RAP circuit problem then it has nothing to do with the BCM. The BCM is not connected to the stereo system in any way other than providing power to the radio head unit. It could be the Monsoon amp or its wiring. Firebird or Camaro? The amp powers all speakers in Camaros but not the tweeters in Firebirds so if you have a Firebird and all speakers cut out except the tweeters then you can be reasonably sure the amp is involved.
The alarm going off randomly is not directly related to the BCM... 99.9% of the time it's due to water getting in the shock sensor under the right quarter trim in front of the spare tire. You should unplug it (the alarm will still work except for impact detection) and confirm that the false alarms stop. Then you can either leave it unplugged if the impact alarm is not important to you or you can buy an aftermarket replacement - there are several makes and models available that will work.
I disconnected the shock sensor in the back and it still goes off. There is a lot of "Custom" wiring from the previous owners. But I wanted to look for BCM before messing with it because I don't know how to solder. I also looked at mine they don't look bad.
And for the stereo where is the AMP and how do I know if I have the Monsoon amp or not. my car is a Camaro its got the speaker webbing in the back by the quarter panel but I haven't even looked at it. The speakers go off inconsistently so I haven't been able to take a test light to everything yet.
The Monsoon amp is located in basically the same place as the alarm shock sensor (in front of the spare tire). There is a photo of the location in the Monsoon FAQ sticky at the top of the section.
If there is a lot of modified wiring in the car, are you sure the factory alarm is active and that it isn't an aftermarket alarm producing the false alarms? Replacement aftermarket stereos and alarm systems are the two most common reasons for modified wiring.
The Monsoon amp is located in basically the same place as the alarm shock sensor (in front of the spare tire). There is a photo of the location in the Monsoon FAQ sticky at the top of the section.
If there is a lot of modified wiring in the car, are you sure the factory alarm is active and that it isn't an aftermarket alarm producing the false alarms? Replacement aftermarket stereos and alarm systems are the two most common reasons for modified wiring.
I think so I ripped that **** out and threw it in the trash lmao. It was draining the battery every night. But there is some stuff hooked up to the BCM. I had to put the resistor in the ignition for it to start the car. Otherwise the alarm will set off and the car won't start.
Stuff connected to the BCM wiring could only be an aftermarket alarm (other than a VATS bypass) unless someone was doing something incredibly stupid.
They had a remote start system, an alarm bypass, and an aftermarket alarm all connected to wiring under the steering column. I removed all of it cause it was draining the battery but there is a wiring from BCM going towards where all the aftermarket electronics were. But I still don't see why the alarm would go off if the shock sensor is unplugged. It would mean there has to be power going to whatever wire/module that tells the car to set off.
YES YES.! I need it bad! Im a newbee and dont know how to pm yet
Originally Posted by 69gto96z
I’m in the process of re-wiring my entire car, no longer need the BCM. 2002 SS. Worked perfectly. PM me if interested.
I need that info bad! I came on here looking for that info and you got exactly what i need!
How can i get jt from you? Im trying to figure out how to pm?
Email is usstickers@gmail.com
I need that info bad! I came on here looking for that info and you got exactly what i need!
How can i get jt from you? Im trying to figure out how to pm?
Email is usstickers@gmail.com
They are vehicle specific and it reads up to you ignition so it wont start if its the wrong OHMs in the resistor. I've tried i got one from the junkyard and plugged it in car wont start.
Installing a used BCM is possible but requires some extra work. If you get the original ignition key that went with the BCM (or the seller can tell you the resistance on the key pellet) then you just have to buy an ignition key blank that has the same resistance and get it cut to match your existing key (so it will turn the ignition cylinder). If you don't get that information then you will have to buy all 14 possible resistor combinations and try each one until you find the one that matches the used BCM, then get a matching key cut. There are VATS bypass modules which allow you to select resistor values using a rotary switch or series of DIP switches... expensive but easier than combining resistors manually (most of the original values can't be matched with just a single resistor).
Installing a used BCM is possible but requires some extra work. If you get the original ignition key that went with the BCM (or the seller can tell you the resistance on the key pellet) then you just have to buy an ignition key blank that has the same resistance and get it cut to match your existing key (so it will turn the ignition cylinder). If you don't get that information then you will have to buy all 14 possible resistor combinations and try each one until you find the one that matches the used BCM, then get a matching key cut. There are VATS bypass modules which allow you to select resistor values using a rotary switch or series of DIP switches... expensive but easier than combining resistors manually (most of the original values can't be matched with just a single resistor).
Can I just get the resistor and shove it in the back end of the connector? I can just program my keyless entry to it? and it will work as normal?
They are vehicle specific and it reads up to you ignition so it wont start if its the wrong OHMs in the resistor. I've tried i got one from the junkyard and plugged it in car wont start.
Can I just get the resistor and shove it in the back end of the connector? I can just program my keyless entry to it? and it will work as normal?
Well, yes you could do that. Someone on another LS1 forum foolishly did that and bragged about how much quicker it was. It must have saved him 20 minutes or so. It's also a good way to end up with a failure down the road that would be hard to diagnose and could leave you stuck somewhere with a car that won't start. If you're going to do it, spend a few more minutes and do it right... solder or at least use crimp connectors and insulate properly (electrical tape is sufficient).
Only one of the 15 possible VATS resistance values can be recreated with a single standard off-the-shelf resistor - all the others require at least two resistors wired either in series or parallel, so that makes shoving them in the back of the connector even more likely to fail.
Here is a table of the possible VATS resistance values and examples of how they can be matched using off-the-shelf resistors (10% resistors are acceptable but 5% would be better, all combinations shown are less than 1% off from the expected value)...
VATS Resistance Values. + means wired in series and || means wired in parallel.
NOTE: GM used 15 different resistance values across all product lines but only 14 of those were ever used on f-bodies. That's why you'll see 14 or 15 used interchangeably when talking about VATS in these forums.
He was just offering to sell the BCM from his car that he no longer needs because he's rewiring. If you need one, this would be a good opportunity because you would be able to get the VATS key resistance value to match.
Well, yes you could do that. Someone on another LS1 forum foolishly did that and bragged about how much quicker it was. It must have saved him 20 minutes or so. It's also a good way to end up with a failure down the road that would be hard to diagnose and could leave you stuck somewhere with a car that won't start. If you're going to do it, spend a few more minutes and do it right... solder or at least use crimp connectors and insulate properly (electrical tape is sufficient).
Only one of the 15 possible VATS resistance values can be recreated with a single standard off-the-shelf resistor - all the others require at least two resistors wired either in series or parallel, so that makes shoving them in the back of the connector even more likely to fail.
Here is a table of the possible VATS resistance values and examples of how they can be matched using off-the-shelf resistors (10% resistors are acceptable but 5% would be better, all combinations shown are less than 1% off from the expected value)...
VATS Resistance Values. + means wired in series and || means wired in parallel.
NOTE: GM used 15 different resistance values across all product lines but only 14 of those were ever used on f-bodies. That's why you'll see 14 or 15 used interchangeably when talking about VATS in these forums.
I got one a BCM from the junkyard i ordered a pack of the GM VATS resistors comes with all 15 resistors. Im sure i can figure a way to make a good connector rather than the dinky through the back. Ill test and see if it starts up. Tell ya how it goes.
11-14-2020, 12:29 PM
98-02 Body Control Module 
