BCM problems---have VATS bypass-do I need flashing?
Thread Starter
Teching In
Joined: Oct 2021
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BCM problems---have VATS bypass-do I need flashing? OK, I have three birds with many screwy problems that come and go. lights, radio, windows, etc. 1995, 1997 and a 2002. Ive found vids on how to take the BCMs apart and fix loose solder joints. Thing is, what if I cant fix them? You can buy new or used but all the info Ive found says it has to be flashed by dealer etc. My VATS went bad on all of them and Im installing a bypass set on them. What will that do---will I then be able to use any new BCM? Isnt the flashing or reprogramming just for the stupid VATS system?
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Programming of a BCM... yes and no. A new BCM must be programmed to match the key ignition key resistor but it does that completely automatically the first time you start up the car after the BCM replacement. The BCM will match itself to the first key used to start the car and after that it can never be reprogrammed again. You don't have to go to a dealer - just install your new BCM and start the car.
Used BCMs are a completely different thing. Since they can't be reprogrammed after matching to the first key use, you will have to figure out which of the 14 different resistor values it was originally matched to. The best way is to get the matching ignition key from the seller and then just measure the resistance and get a new key blank with that resistance cut to match your old key. With a VATS bypass, you can make sure you have resistors for all 14 values and then try each one until you find the one that works.
Problems with lights have nothing to do with the BCM since it doesn't control lights other than to flash the parking lights for locking and unlocking or when the (optional) alarm is triggered. That is unless you're talking about some of the idiot lights in the dash (seat belt, parking brake, security, etc.)
Problems with power windows and the radio cutting out intermittently are almost certainly related to the cold solder problem interrupting the Retained Accessory Power (RAP) circuit which provides power to the windows and radio during normal operation as well as for about 10 minutes after the ignition is turned off. Neither lights nor the RAP solder problem have anything to do with VATS other than being in the same physical box.
Used BCMs are a completely different thing. Since they can't be reprogrammed after matching to the first key use, you will have to figure out which of the 14 different resistor values it was originally matched to. The best way is to get the matching ignition key from the seller and then just measure the resistance and get a new key blank with that resistance cut to match your old key. With a VATS bypass, you can make sure you have resistors for all 14 values and then try each one until you find the one that works.
Problems with lights have nothing to do with the BCM since it doesn't control lights other than to flash the parking lights for locking and unlocking or when the (optional) alarm is triggered. That is unless you're talking about some of the idiot lights in the dash (seat belt, parking brake, security, etc.)
Problems with power windows and the radio cutting out intermittently are almost certainly related to the cold solder problem interrupting the Retained Accessory Power (RAP) circuit which provides power to the windows and radio during normal operation as well as for about 10 minutes after the ignition is turned off. Neither lights nor the RAP solder problem have anything to do with VATS other than being in the same physical box.
Thread Starter
Teching In
Joined: Oct 2021
Posts: 37
Likes: 4
Thanks much! That was extremely helpful. Ive found this---is it a total solution so I dont have to solder or change anything?
https://www.ebay.com/itm/28270041228...BoC5kgQAvD_BwE
https://www.ebay.com/itm/28270041228...BoC5kgQAvD_BwE
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
No, that isn't even a complete VATS bypass. VATS disables your car in two ways... it disables the fuel enable signal from the BCM to the PCM preventing fuel from getting to the engine and it removes the ground from the starter relay so the starter won't turn. This module only provides an alternate fuel enable signal to the PCM. It doesn't do anything about the starter relay - you have to rewire the ground there as it mentions in the description. And it does nothing about the security light in the dash which will still be lit all the time. A resistor based VATS bypass will take care of all those things in one simple installation.
Besides, that will only take care of VATS, and as I mentioned, VATS has nothing to do with your windows and radio... only the solder fix or a new BCM will solve that problem. And the BCM is not related at all to any lighting problems, so that is a completely separate problem.
Besides, that will only take care of VATS, and as I mentioned, VATS has nothing to do with your windows and radio... only the solder fix or a new BCM will solve that problem. And the BCM is not related at all to any lighting problems, so that is a completely separate problem.
