How to disable MKIII Anti-Theft Device?


May 3, 2007

I have a 87' MKIII Supra Turbo and I didn't know it had an anti-theft device until I pulled it out of the garage, parked it in the driveway, and attempted to start it to pull it back in the garage. Unfortunately, the car won't start and the lights are blinking and horn on. I have the original key for the car. The hood latch is closed, same with the trunk. I am able to insert the key and lock/unlock the drivers door with the key, but unfortunately the passenger side door the key does not turn it. I have to manually lock or unlock the passenger side.

My question is, can I bypass or disable this alarm so that I can start the car and pull it back in the garage?

I did close all doors, and locked/unlocked the drivers side door a few times and the headlights went down and alarm stopped... but then... when I open the door the anti-theft device goes back on and I cannot do anything.

Any tips? Can I bypass this somehow?


Feb 28, 2013
Tampa Bay Area
I had this problem when I first purchased my '87 Supra In 1996. What can happen is on the back of the drivers key lock is the electric actuator for the alarm system. A crescent shaped sliding copper contact becomes detached from a plastic rivet that holds it in place. I repaired mine by removing the key lock, opening up the plastic cap that houses the contacts and carefully putting the crescent shaped copper contact over the rivet and mushrooming the rivet again. That repair has held up until now.


Active Member
Dec 30, 2005
If you want to semi permanently disable the system, without cutting or removing anything:

Open the hood, and look at the latch on the rad support. The will be a black plastic cover, that hides a switch. This switch tells the anti theft system whether the hood is open or not. If you bridge the two wires together, it tells the system that the hood is open. If it thinks the hood is open, the system will never arm.
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Jeff Lange

Staff member
Mar 29, 2005
Calgary, Canada
If you want to fully disable the system, you can get the following part numbers from Toyota and use it to build a bypass junction connector to replace the anti-theft computer.

90980-10806 - Housing, Connector
82998-12330 - Terminal with Repair Wire; Qty: 2

Solder/crimp and heat shrink the two repair wires together and install them into pin locations 5 and 13 in the connector housing and lock the secondary terminal lock.

Disconnect and, optionally, remove the anti-theft computer and plug the new junction connector in its place.