# Vehicle Anti-theft system by-pass



## DougM (Aug 3, 2009)

Has anyone every had trouble with the existing vehicle anti-theft system when doing a conversion? I am in the closing stages of my 2000 Mazda B3000 conversion and I can't figure out how to stop the headlights from flashing when use the existing key switch to activate the main contactor. I have searched many forums and no luck yet.
I have removed the vehicle ECU (not possible to re-install because I threw away the wire harness with the ICE) and the security module is disconected.
Any suggestions?


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## McRat (Jul 10, 2012)

Not a Mazda guy, but ...

The Body Control Module is what causes the headlights to come on most cars.
It also does power windows, instruments, interior functions, wipers, etc.

Since you already got rid of the ECM, this might be problematic, if it's in charge of communicating via the OBDII port. You won't be able to reflash via the port.

You really need to ask the question at a Mazda performance forum, where folk do engine swaps. On GM's, we program that feature out of the computer. I imagine the same is true for other brands.

Somebody might be able to reflash your BCM if you send it to them.


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## DougM (Aug 3, 2009)

Thanks, i was hoping it didn't have anything to do with the ECU. I thought the flashing must be controlled by a relay, but i can't find it. I've tried disconnecting almost everything in the instrument pannel, no luck. Mazda pick-up trucks of this era are clones of the Ford Ranger. Any Ranger guys see this before?


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## emosun (Jul 21, 2012)

Well I do know that on a ford vehicle like that , the antitheft has to be disabled with the remote on the keys.

Even if you have the correct set of car keys , the system will assume the locks are being picked and the alarm will sound. Only the remote can enable and disable the alarm.


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## DougM (Aug 3, 2009)

I got it! It wasn't the security system causing the headlights to go haywire. It was the daytime running light module. Apparently Ford/Mazda DRL modules have a history of failing in this manner, causing the lights to flash.
Thanks for the replys, and I hope this can help others.


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