1990 SC anti-theft or security system

Brett Schneider

Registered User
I bought a 1990 SC and it looks like it has a factory security system. When I hook up the battery the lights blink and the motor will not turn over unless I bypass the ignition and straight off the solenoid. Does anyone know how to bypass the security system or how to permanently remove it?
 
Auto or manual trans? Does it have the switch that requires the brake pedal to be pressed? I don't recall much of a 'factory security system' other than that and I think it's only w/auto trans.

Did you check the multi-wire ignition switch down on the side of the steering column (not the lock cylinder) to see if it is coming apart when the key is turned?
 
Auto or manual trans? Does it have the switch that requires the brake pedal to be pressed? I don't recall much of a 'factory security system' other than that and I think it's only w/auto trans.

Did you check the multi-wire ignition switch down on the side of the steering column (not the lock cylinder) to see if it is coming apart when the key is turned?
It is auto trans and I did press on the brake but that did not fix the issue. I also have not checked the multi-wire ignition switch but will.

Thanks
 
If it is factory system, light in dash will flash-I think its on right side of firm ride light?
Sitting in drivers seat or standing outside,you will also here relay's in left side of trunk cycling/clicking as the activate horns/lights.

Also, I dont think it will even allow the IRCM to power up the ECM & fuel pump, so it shouldn't start by bypassing starter solonoid.

Refer to your EVTM to verify though
 
If it is factory system, light in dash will flash-I think its on right side of firm ride light?
Sitting in drivers seat or standing outside,you will also here relay's in left side of trunk cycling/clicking as the activate horns/lights.

Also, I dont think it will even allow the IRCM to power up the ECM & fuel pump, so it shouldn't start by bypassing starter solonoid.

Refer to your EVTM to verify though
Right, it wouldn't start with bypassing the solenoid it would just turn the motor over. The car did have damage in the passenger rear quarter where the brains of the security system is located.
 
Geez, I'm not sure how to go about bypassing the module?
Its tied into so many other systems, keyless, power locks, door lock tumblers, door & trunk latch's, the IRCM, head/park lights, instrument cluster, horn. I know there is even difference's between sold in U.S. & sold in Canada cars because of the passive vs active seat belt system's. No idea why alarm would be tied into that, but it shows different diagram's in EVTM & wiring supplement fold out pages I have for my 90.

Others on here may know more or be able to direct you better.(Hopefully)
 
The car did have damage in the passenger rear quarter where the brains of the security system is located.
If that's true, it sounds like aftermarket. Also, consider the difference between factory installed and dealer installed.

Summary of items in -left- rear quater (driver side), according to the Component Locater pdf (example is early model SC):
- keyless entry module -or- illuminated entry timer
- anti-theft module
- anti-theft alarm relay
- anti-theft horn relay
- disarm relay
- door ajar diodes (9" from passive restraint module, inside harness)
- passive restraint module
- inertia switch
- fuel pump relay


EVTM 112-4 also lists the following in the same general area:
- anti-theft inline fuse (in window regulator harness)
- anti-theft lamps inline fuse (in window regulator harness)
 
Oh, I must have missed that. If Bretts module is located in the right 1/4 it must be aftermarket or dealer installed.
It's anybody's guess really on where it is tied into the cars wiring or how it will be effected by removing or bypassing it.
 
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