: 1991 Brougham - Automatic Door Locks - Theft Deterrent System

03-27-11, 12:53 PM
I have 1991 Brougham, 5.7 L with option package C. Car has 47,000 miles and is generally in excellent condition. Just bought it a month ago and have couple of questions about the "Automatic Door Locks" and the factory theft deterrent system.

The factory theft deterrent system does not arm when locking the doors, meaning the dashboard light continues to flash after pressing the power lock switch; it never glows steadily. Also, the automatic door looks (which I believe were standard equipment; please correct me if I'm wrong - the window sticker includes a "Auto Electric Pwr Door Locks" line item) only work when shifting back into park. The doors do not lock automatically when shifting into gear. Also, this year is supposed to have "Central Locking" like many european cars, whereby turning the door key to left/right and holding for 2+ seconds triggers the power door locks for all doors). The central locking feature does not work.

The previous owner (who owned the car for 20 years) installed an aftermarket remote starter (which I have since had removed at the Cadillac dealer because it didn't work and I want the car to be original).

I know that there is a connection between starter and theft deterrent system and that there is a connection between power door locks and and the theft deterrent system, which is why i'm mentioning all of this.

I'd like for the automatic/central locks and the factory theft deterrent system to work. Any thoughts about where to start? I have the factory service manual and it goes through several steps about diagnosing problems but I don't have a multi-meter or anything to help test electrical components. In the end I may need to buy replacement theft deterrent controller and auto lock controller but don't want to do that, of course, unless I know that's the real issue.

1) Is there place I should be looking that might fix both systems (e.g. a door lock sensor that is grounded such that auto locks/theft deterrent system that thinks a door is open, hence won't arm/lock?
2) What are the part numbers for theft deterrent and auto-lock controllers?
3) Does this 1991 truly have the central locking feature? The owners manual says that "some cars are equipped", so perhaps I don't have this feature after all?
4) Could there be a wiring problem/short associated with the one-time remote starter that disabled the theft deterrent system? The car has no problems starting using the key.


03-27-11, 06:51 PM
Turning the key and holding it unlocks the doors. I don't think it locks them.

The rest sounds like it is all related to the alarm that was removed. It shouldn't be that hard to dig up under the dash and look for the wires that were cut or spliced in to add in the aftermarket alarm. It would probably be easier to just take it somewhere where they install alarms and tell them what's going on and see how much they would want to look at it.