May 18, 2016, 05:53 PM
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Does New BCM have to be Flashed by the Dealer?
Registered User
Joined: Apr 2015
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Old BCM Post Sorry to bother you, just really need that question answered and haven't been able to find a straight one for days.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Believe it or not, the easiest way to tell if a vehicle needs its new BCM programmed is to look at the radio. If it has the 1.5 DIN radio used in 4th generation f-bodies and most other GM vehicles up to around 2001 (varies by model) then the BCM is plug-and-play and will match itself to the first key used automatically. If the vehicle has a double DIN radio then it has the newer electronics which encode the VIN into both the radio and the BCM for theft prevention purposes. Those require the new BCM to be programmed.
Teching In
Joined: May 2018
Posts: 2
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2013 camaro There is no programming involved - the dealer is either clueless or trying to rip you off. The only thing that the BCM has to learn is the resistance value of your ignition key for the VATS system. A new BCM learns the resistance value of the first key used and it can't be changed after that.
All you have to do is plug in the new BCM and start the car with your regular key. There are no special programming steps involved. Then call your dealer and tell them to look it up in the service manual. (It's not Nimnicht, is it?)
All you have to do is plug in the new BCM and start the car with your regular key. There are no special programming steps involved. Then call your dealer and tell them to look it up in the service manual. (It's not Nimnicht, is it?)
Teching In
Joined: May 2018
Posts: 9
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From: Florida
Teching In
Joined: Jul 2019
Posts: 2
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Need help So I have a 2005 Chevy trailblazer. Last month, after fillingbmy tank up at the gas station, my car wouldnt start or turn over. All lights worked and windows and radio still worked. Had my car towed home. 5 different ppl looked at my car. I was told it was the battery (bought a new one), it was the starter (had it tested and it worked), alternator (no problem), fuel pump (did squirt test, it worked), relay fuses (had a couple replaced), ignition switch (left alone), and finally had a diagnostic done (no codes popped up) also just want to state that I have not had a check engine light come on before or even after car stopped working. The guy who did the diagnostic also used a tool and tested the relay and fuses under my hood and told me the BCM was getting a low voltage reading and that he believes that to be the reason my car will not start or turn over or move out of the park gear. Upon googling, since I have no idea about cars, I've read mostly that the BCM is for lightening, power windows, and stuff like that.. but I havent read too much about a car not starting, turning over, or gear shift not moving because of it. The guy told me to replace the BCM will be around 350. And then to program it will be another 100 or so... I just want to make sure this is the correct reason as to why my car wont start before I spend this type of money on it. Does this sound right? Or am I back to square 1 on what could be causing my vehicle not to start or anything?
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
The BCM in your Trailblazer is not remotely like the one discussed here for f-bodies. It controls many more features than the simpler model discussed. It has three connectors with a total of 96 wires (compared to only 38 wires in an f-body BCM). I would not be surprised if a failure could cause your starting problem but this is not something that needs to be guessed - the module can be tested with the right equipment that a dealer would have. That would let you know for sure whether your BCM is faulty and needs to be replaced.
The quoted price is also too high. The BCM for your model costs under $200 online (most are under $150) and can be replaced in 30 minutes or less. It's under the left rear seat. Just move the seat to the "cargo position" to access the electrical box underneath, open up the box, disconnect the three connectors and pull out the BCM. Installation is the reverse. Programming is required and I suppose $100 is not completely unreasonable for that.
The quoted price is also too high. The BCM for your model costs under $200 online (most are under $150) and can be replaced in 30 minutes or less. It's under the left rear seat. Just move the seat to the "cargo position" to access the electrical box underneath, open up the box, disconnect the three connectors and pull out the BCM. Installation is the reverse. Programming is required and I suppose $100 is not completely unreasonable for that.
Teching In
Joined: Jul 2019
Posts: 2
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Online? The BCM in your Trailblazer is not remotely like the one discussed here for f-bodies. It controls many more features than the simpler model discussed. It has three connectors with a total of 96 wires (compared to only 38 wires in an f-body BCM). I would not be surprised if a failure could cause your starting problem but this is not something that needs to be guessed - the module can be tested with the right equipment that a dealer would have. That would let you know for sure whether your BCM is faulty and needs to be replaced.
The quoted price is also too high. The BCM for your model costs under $200 online (most are under $150) and can be replaced in 30 minutes or less. It's under the left rear seat. Just move the seat to the "cargo position" to access the electrical box underneath, open up the box, disconnect the three connectors and pull out the BCM. Installation is the reverse. Programming is required and I suppose $100 is not completely unreasonable for that.
The quoted price is also too high. The BCM for your model costs under $200 online (most are under $150) and can be replaced in 30 minutes or less. It's under the left rear seat. Just move the seat to the "cargo position" to access the electrical box underneath, open up the box, disconnect the three connectors and pull out the BCM. Installation is the reverse. Programming is required and I suppose $100 is not completely unreasonable for that.
would you happen to know where online? I have been trying to look and when I think I've found one, I get worried that it's the wrong one.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
I don't have a parts manual for that model so I just used the listings on sites like Rock Auto. If you're concerned about different options, you could go to your local dealer and ask them to price a new BCM for you. If their price is too high, tell them you'll have to wait but ask them to give you the part number for when you come back. You can then use that part number to confirm what you order online.
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Verdad Gallardo Joined: Nov 2003
Posts: 11,331
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From: Jacksonville, FL (originally from Toronto Canada)
First, what problem leads you to the conclusion that you need a new BCM? There may be other options. BCMs seldom fail completely.
Second, you can install a used BCM from a junk yard if you can match VATS. If you get the original ignition key from the donor car then VATS is no problem - just buy a key blank with the resistor that matches the donor key and have that cut to match you current key. Otherwise, you'll have to try each of the 14 possible key resistor values with the used BCM until you find the one that works then get a new key with that value. You can do that with a pile of various resistors but that can get messy and tedious. Or you can buy a VATS box which has every combination attached to a dial switch so that you can just cycle through them until you find the right one - much easier but costs more.
Second, you can install a used BCM from a junk yard if you can match VATS. If you get the original ignition key from the donor car then VATS is no problem - just buy a key blank with the resistor that matches the donor key and have that cut to match you current key. Otherwise, you'll have to try each of the 14 possible key resistor values with the used BCM until you find the one that works then get a new key with that value. You can do that with a pile of various resistors but that can get messy and tedious. Or you can buy a VATS box which has every combination attached to a dial switch so that you can just cycle through them until you find the right one - much easier but costs more.
Staging Lane
Joined: Dec 2017
Posts: 52
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From: Virginia
No it has not failed completely but my windows and radio hardly work anymore and I wanted a New BCM. I am very aggravated that GM would discontinue the BCM that has keyless entry but still sells the BCM w/o keyless entry?? I do not want a used or remanufactured BCM and I do not know how to solder so that is not an option either and I have been trying to find a Mechanic that can solder and am not having much luck with that. Just wanted to see if I have any other options.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Learning to solder is one option. It's really not difficult or expensive. You can get a soldering iron and solder for $15 or less. Then just take a couple of pieces of wire and practice soldering them together... you'll get the hang of it in less than an hour. Resoldering the joint on the BCM circuit board is even easier - you don't have to be particularly neat or have professional skills, you just need to heat the existing solder to make it reflow on the joint while avoiding applying so much heat that the board melts. That's really easy - just let the soldering iron reach its full temperature (i.e. don't be in a hurry, the warmup takes time) than apply the tip to the joint for just a few seconds as you watch the solder melt enough to flow. Then pull the iron away and you're done.
GM (and all manufacturers) discontinues parts that don't sell. They are under no obligation to continue to produce parts other than those necessary to fulfill their warranty obligations. Beyond that, they make and stock parts that sell and discontinue the ones that don't. In this case, either the non-keyless BCM is still selling or, more likely, they had excess inventory of that part while the keyless model sold out over time. These cars are at least 17 years old now so they probably stopped making these replacements years ago and the one part eventually sold out and was discontinued while there is still inventory left of the other part.
GM (and all manufacturers) discontinues parts that don't sell. They are under no obligation to continue to produce parts other than those necessary to fulfill their warranty obligations. Beyond that, they make and stock parts that sell and discontinue the ones that don't. In this case, either the non-keyless BCM is still selling or, more likely, they had excess inventory of that part while the keyless model sold out over time. These cars are at least 17 years old now so they probably stopped making these replacements years ago and the one part eventually sold out and was discontinued while there is still inventory left of the other part.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Assuming you mean part number 9353681, it will probably work but there is no guarantee since that part number is not listed in the 98-02 f-body parts manual. Assuming it works, you would lose keyless entry (AU0) and, if you have it, the optional factory alarm system (UA6). Several parts sites are already reporting it discontinued and unavailable. Some list it as special order and out of stock. So you may not be able to get it anyway. And if you do, it will be over $200 - a lot of money for an incorrect part compared to a $10 soldering iron. But it's your car and your money so if you are really that terrified of attempting the proven repair then by all means go for it.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Okay, the same question as asked earlier applies... what makes you think you need a new BCM? The BCM can almost always be repaired to solve the most common problems. Unless the car has been struck by lightning, flooded or experienced some similar physical damage, there is little chance that the BCM actually needs replacement. There's no point throwing $250 parts at a problem without a firm diagnosis. So what problem leads you to believe a new BCM is necessary?
I found one place claiming to sell remanufactured BCMs for $350 including a $100 core charge. You can always get a used one from a junk yard. You'd want to get the original ignition key that matched it to simplify VATS matching but it can be done even without the key with a little patience.
I found one place claiming to sell remanufactured BCMs for $350 including a $100 core charge. You can always get a used one from a junk yard. You'd want to get the original ignition key that matched it to simplify VATS matching but it can be done even without the key with a little patience.
Teching In
Joined: Jul 2019
Posts: 12
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I took the bcm apart to make do the common solder fix to little prevail was not my issue. Upon further inspection of the board, I noticed a couple spots on the board actually looked burnt or fried.
Last edited by chad cunningham; Jul 31, 2019 at 03:12 PM.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Honestly, I don't see anything in those photos that is worse than the normal overheating from the sloppy manufacturing provided by the lowest bidder at the time these cars were built. It looks pretty much like every other BCM I've examined but If I've overlooked something, please point it out.
What are the symptoms you're experiencing that make you suspect the BCM?
What are the symptoms you're experiencing that make you suspect the BCM?