secuirity light,vats system
If your car is not starting due to the VATS, you can simply bypass it with a resister wired in line with the BCM.
If the SECURITY light is on steady and the car still starts then the system has detected a fault while running where it could see a resistance but it doesn't match the original key. The car should continue to start until you disconnect and reconnect the battery at which point it will no longer assume it's a system fault and it will prevent you from starting the car. If the light is flashing then it can't see any resistance as though a key without a resistor pellet was being used. In this case, the car won't start.
In many cases, a system fault is caused merely by bad contact due to grime on the key and/or in the ignition cylinder. Use a pencil eraser followed by rubbing alcohol to clean the key contacts then clean the ignition cylinder with spray electronics cleaner and a pipe cleaner.
On an older model like this, it could also be caused by worn contacts on the key. Try a different key if you have a spare.
Bypassing is basically the same process of installing resistors across the white/black and purple/white VATS wires at the base of the steering column. Search on this forum for "vats bypass" to find lots of information on how to do it.
It is possible that the BCM might be the culprit but it's best to go with the cheap fix first before spending money on a BCM. Since your security light isn't flashing, you know that the wiring is intact and that the BCM is reading some resistance, just not the right resistance. If cleaning doesn't resolve the issue, you can bypass VATS with resistors, eliminate VATS by programming the PCM to ignore the missing fuel enable signal and wiring a separate ground for the starter relay coil, or buy a new BCM.
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can use a bypass resistor to replace key and cylinder but needs to be same value as key.
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If your key does match within 10% then you'll want to determine if VATS in the BCM is seeing the same value. Unplug the blue 32-pin connector from the BCM and measure the resistance between the white/black wire and the purple/white wire (with the key in the ignition of course). The two wires are in different rows on the connector. There is only one white/black wire but there are two purple/white wires close to each other - you want the one closest to the end of the connector between a black wire and an open space (the other one is between that blank space and a dark green wire). Check that the resistance is within 10% of the same value in the list that you found with the key. If not, you've got something changing the resistance. That's usually dirt and grime on the contacts but it could be one of the connectors not solidly plugged together or even corrosion within the connectors. If the measurement at the BCM still matches, then check the connector for any corrosion or dirt and plug it back into the BCM. Sometimes that will fix the problem just because the connection might be tighter. Otherwise you'll probably have to replace the BCM. Even a bypass wouldn't work because the BCM is receiving the correct value but not responding to it properly.
I haven't mentioned the possibility that you get no reading at the BCM (infinite resistance or open circuit) because that would make the security light flash rather than stay solid. But if you do experience that, you'll have to look for where the two wires between the ignition cylinder and the BCM are broken or disconnected. First place to look is the connector at the column under the dash.
put that at the connection of BCM for passkeyII.
youll need a key cut that has no resistor pellet. if it starts and light goes out
you have a problem in that circuit.
Someone that's handy with a meter can check it at the BCM and see if its getting what would be key resistor value
this is an easy way of bypassing the passkey system for diagnosis or removal.
If you want to leave it that way install a switch inline that hidden. OR do a correct fix.
if the problem is in the wiring or the device that reads the key at the ignition lock
this procedure will check it.I suggest a key with no resistor so that if its not the wiring or reader
then you wont double the resistor value.This is much easier than tearing into steering column
and cutting wires just for diagnosis.Good Luck







