: 1991 Brougham Theft deterrent system



JTG1536
03-02-09, 05:51 PM
Hey All,

Here goes my first post.

I have a '91 Brougham and I am having a couple of problem with the Theft Deterrent System (TDS) .

Here is problem #1...

If, I choose not to not activate the TDS .The light on the dash continues to blink for days .. I've tried inserting key in door locks and turning it on and off. Again, leaving it alone after. The light still blinks !!!

Problem #2.

If, I choose to activate the TDS . The light will go off on the dash ( blinking finally stops !!!), but after a few minutes or sometimes up an hour later . My alarm will go off .. I have to go and unlock door to de-activate it. The alarm stops ...... But, once again the light will stay blinking..

As you can see the is really just one problem but with two parts to it.

Any and all help would be great appreciated.

Thanks,

Ken

sven914
03-03-09, 09:48 PM
I have the Theft Deterent System diagnostic procedure for my 89 Brougham. I wouls assume the procedure is the same, however the wire colors may be different. I suggest that if your planning on repairing your own Cadillac, that you aquire a Cadillac Factory service manual. Here are several on eBay (http://shop.ebay.com/items/__1991-Cadillac-brougham-service-manual_W0QQ_nkwZ1991Q20CadillacQ20broughamQ20servi ceQ20manualQ20QQ_cqrZtrueQQ_nkwuscZ1991Q20Cadillac QQ_nkwuscZBrougamQQ_nkwuscZserviceQ20manual?_rdc=1 ).

The Diagnostic and Rpair procedure is as follows: The first thing you have to do is aquire a 12 volt test lamp.
1. Sit in

sven914
03-03-09, 11:36 PM
Sorry about that, Firefox messed up and wasn't running spell check, it was only working in "edit post", and then I got timed out because it took more than 40 minutes to type everything.

I have the Theft Deterrent System diagnostic procedure for my 89 Brougham. I would assume the procedure is the same, however the wire colors may be different. I suggest that if your planning on repairing your own Cadillac, that you acquire a Cadillac Factory service manual. Here are several on eBay (http://shop.ebay.com/items/__1991-Cadillac-brougham-service-manual_W0QQ_nkwZ1991Q20CadillacQ20broughamQ20servi ceQ20manualQ20QQ_cqrZtrueQQ_nkwuscZ1991Q20Cadillac QQ_nkwuscZBrougamQQ_nkwuscZserviceQ20manual?_rdc=1 ).

The Diagnostic and repair procedure is as follows: The first thing you have to do is acquire a 12 volt test lamp and a Digital Volt Ohm Meter (DVOM).

1. Sit in the passenger front seat with all doors closed. Reach over and turn the IGNITION SWITCH to RUN and back to OFF. Open the RH Front door and lock it. Close the RH Front door and wait 5 seconds. Pull up the RH FRONT DOOR LOCK CYLINDER and open the RH front door. If the horn and lights come on, continue to step 2. If they do not come on, skip to step 5.

2. With the alarm still going off, turn the ignition to START. If the starter does not operate, continue to step 3. If the starter does operate, skip to step 13.

3. With alarm still going off, get out of vehicle and turn the door lock to UNLOCK using the key. If the alarm stops, continue to step 4. If the alarm does not stop, skip to stop 16.

4. Turn the ignition to START. If the starter operates, the system is operating normally. If the starter does not operate, skip to step 21.

5. Backprobe THEFT DETERRENT RELAY (my book only describes it as being on the RH side of the brake pedal support) connector with a 12 volt test lamp from cavity A (I woulds assume the go in alphabetical order from right to left) to chassis ground. If the lamp does not light, then repair open in IN-LINE FUSE A or the BLACK/YELLOW wire that runs from the in-line fuse to the theft deterrent rely and controller. If the lamp lights, continue to step 6.

6. Backprobe theft deterrent relay with a test lamp from cavity D to chassis ground. If the lamp does not light, repair open in IN-LINE FUSE B or the DARK GREEN/WHITE wire that runs from the fuse to the relay. If the lamp lights, continue to step 7.

7. Connect a fused jumper from relay cavity F to chassis ground. If the horn and lights operate, remove jumper and continue to step 8. If the alarm does not operate, check wiring from the relay to the horns and lights; if wires are good, replace relay.

8. Disconnect the relay and the THEFT DETERRENT CONTROLLER (it is attached above the relay) connectors. Connect a digital Volt OHM Meter (DVOM) from relay connector cavity F to controller connector cavity F. Set the meter to read resistance (OHMs). If resistance is less than .003 OHMs, reconnect relay and continue to step 9. If the resistance is greater than .003 OHMs, repair open in the BLACK/WHITE that runs from the relay to the controller.

9. Backprobe the controller with a test lamp from cavity G to chassis ground. Press the door lock switch to LOCK. If the test lamp lights, continue to step 10. If the test lamp doesn't light, check the power door lock operation. If good, repair open in the LT BLUE wire that runs from the door lock switches to the relay, or the open in YELLOW wire that runs from the LH FRONT SEAT SWITCH to the controller.

10. Disconnect the controller connector. Connect a test lamp from connector cavity N to chassis ground. If the test lamp lights, continue to step 11. If the lamp doesn't light, repair the BLACK/YELLOW wire (mentioned above).

11. Connect a DVOM from controller connector cavity A to chassis ground. If resistance is less than .003 OHMs, continue to step 12. If the resistance is grater than .003 OHMs, repair the BLACK ground for the controller.

12. Connect a DVOM from controller connector cavity J to chassis ground. Measure resistance with the RH doodr open. If resistance is more than .003, repair open in the LT BLUE wire that runs from the controller to the door jamb switches, or replace the door jamb switch. if resistance is less than .003, replace the controller.

13. Disconnect the controller connector. Backprobe the starter interrupt relay (above the lower base of the steering column) connector with a test lamp from cavity 5 to chassis ground. Turn the ignition switch to RUN. If the test lamp lights, continue to step 14. If the test lamp does not light, repair open in the PINK wire that runs from the ignition switch to the starter interrupt relay.

14. Disconnect the starter interrupt relay connector. Connect a DVOM from the relay connector cavity 2 to the controller cavity E, measure resistance. If the resistance is less than .003, reconnect the relay and continue to step 15. If the resistance is grater than .003, repair open in the DARK BLUE wire that runs from the relay to controller.

15. Connect a fused jumper from the controller connector cavity E to chassis ground. Turn the ignition to START. If the starter operates, replace the starter interrupt relay. If the starter doesn't operate, replace the theft deterrent controller.

16. Disconnect both the theft deterrent controller and the theft deterrent relay. Connect a test lamp from relay connector cavity A to cavity F. If the test lamp doesn't light, continue to step 7. If the lamp lights, repair short to ground in the BLACK/WHITE wire (mentioned above).

17. Connect a DVOM from the controller connector cavity H to chassis ground. UNLOCK the door with the key. If resistance is less than .003, continue to step 18. If the resistance is more than .003, repair the LT GREEN, DK GREEN wires that runs from the controller to the door lock cylinders, or replace the door lock cylinder switch.

18. Connect a test lamp from controller connector cavity K to chassis ground. Turn the ignition switch to RUN. if the test lamp lights, continue to step 19. If the test lamp doesn't light, repair the open in the PINK/BLACK wire that runs from the fuse block to the controller.

19. Connect a DVOM from controller connector cavity J to chassis ground. Close all doors and trunk and DO NOT sit in the driver's seat. If the resistance is more than .003, continue to step 20. If resistance is less than .003, repair short to ground in the LT BLUE, TAN, GREY wires, the THEFT DETERRENT DIODE (all are part of the door lock circuit), door lock cylinder switches, door jamb switches, or the trunk lid tamper switch and check the YELLOW wire (mentioned above) if equipped with auto door locks.

20. Connect a test lamp from controller connector cavity G to chassis ground. If the test lamp does not light, replace the controller. If the lamp lights, repair short to voltage in the YELLOW or LT BLUE wires (mention above).

21. Disconnect the controller connector. Turn the ignition to START. If the start operates, replace the THEFT DETERRENT CONTROLLER. If the the starter doesn't operate, then the problem is in the starting system.

I'm not sure which step will fix your specific problem, but if you follow this procedure your probably going to come across it (and maybe some more).

JTG1536
03-04-09, 07:49 PM
Thanks,

I will give it a shot.. Let you know the results later..

Ken

cadillackid64
03-10-09, 02:38 PM
Sounds like a faulty switch, either in the doors or the trunk lock. It's either that or the module is crapped out.