Cadillac Repair: 89 Seville Brake Light and Cruise Control, brake light switch, vacuum switch

Question
First noticed cruise control would not release with the brake pedal and now find out brake lights not working either.  Have checked all fuses and bulbs, haz and turn signals work.

All help appreciated, thanks  John

Answer
Hi John, The symptoms you describe point towards a defective brake light switch and cruise control vacuum switch. If you have a 12 volt test light or voltmeter you will be able to test the switch.

    What you need to do is remove the panel under the dash and locate the brake pedal. Up near where it pivots you will see 2 brake switches...one has a 3/8" vacuum hose and the other just electical connectors. What you want to do is find the wire that has power and then push the brake pedal and see if power is available on the other wire. If you don't or it is intermittant then replace and adjust the switch. If you have a vacuum pump that can be used to verify the cruise vacuum switch is able to release vacuum when pushed otherwise just replace it because it isn't too expensive.

   If you have power on both sides of the brake switch with the pedal pushed you will need to trace the circuits. You could have a bad wire or connector somewhere. Useing a wireing diagram is needed at this point.

   I have replaced alot of switches and that could very well be your problem also. Pull the switch out of the retainer and then push the new switch in so the plunger on the switch is almost all the way into the body with the brake pedal released and both problems should be solved.

   Hope that helps and let me know if you need anymore help. Bill