Hey all…hope someone can help with this one. After recently removing ( and replacing) my dash pad to replace the courtesy switch bezel, I now have no brake lights. I have 12 volts at the pedal switch and it opens and closes normally as it should. Can’t see a burnt fuse (not sure which one it would even be), and all other lights are working. There is no fuse in the emergency flasher slot, but I had working brake lights before this.
any suggestions?
Not a fuse issue if you have power on one side of the switch.
Ok…I really need help with this. I bought a new brake pedal switch AND a new electronic variable flasher today. It made no difference. I still have no brake lights. When I put my test light on one side of the brake pedal switch, it comes up live. When I press the brake pedal in, both sides of the switch go dark. NO power at the sequencer box when brakes are depressed. Signals work, but the sequence seems fast and the rate cannot be varied with the new flasher at all. I was very careful when I removed the dash pad to replace the courtesy switch bezel, and did not remove the instrument cluster at all. I’m really lost…can anyone help?
First verify that your hazard lights work as the hazards and brake light switch are powered from the same 15 A circuit breaker. If the hazards work, while the hazards are on, hit the brakes, did the hazards continue working? If not, then the 15A circuit breaker needs to be replaced or there is a short in the brake circuit pulling more than 15A tripping the circuit breaker.
BTW, make sure the brake light switch you purchased matches the brake system on your car as manual brakes use a different switch than that of power brakes.
On the 69 and 70 Cougars, the brake lights are activated with power from the turn signal switch and the brake light switch. Check the wires at the sequencer with the brakes applied as the left inner brake light is powered by circuit # 442A (Green-Orange) and the right inner brake light circuit #445A (Orange-Blue) are fed from the turn signal switch. Also check circuit #511 (Green) as this provides the power to the Sequential unit from the brake light switch.
If you do not have voltage on these wires when braking, then check the output of the turn signal switch for the 442 and 445 circuits and the brake light switch for the power on 511. If you do not have power on 442 and 445 from the turn signal switch, then check the circuit 511A (Green) at the turn signal switch as this is the input power from the brake light switch. Note the output of the brake light switch feeds both the turn signal switch and to the sequential box.
Hope this helps
Coach Jack
Thank you very much.
Coach Jack, Keep up the good work! You are making a difference.
For anyone still following this thread, it turned out to be the circuit breaker after all. Thanks Coach Jack!
Yeah, Coach Jack alsways seems to hit it right on the money. Helped me out with a diag too.
Hello All, resurrecting this thread with a slight variation - Cruise Control.
I have a 69 XR7 Conv. w/ factory cruise and AC, power brakes. 2nd owner so the good news is most of the wiring is pretty unmolested. I have never used the cruise in my 20+ years with the car as my turn signal lever with the cruise engage button was broken when I bought the car and I could never muster the courage to buy a replacement for $500+.
I have all the same symptoms as the original post, Turn Signals work, tail lights work - Break lights do not, Rear Hazards do not (front do).
I just replaced the turn signal switch because of other sequential issues which were resolved. A short time later the brake lights failed. I have current at the brake switch on both sides when applied. I have no current at the sequential box on any line when brakes are pressed. I suppose it is possible the turn signal switch I just put in has a defect. It worked for a week or two if so… Is there a way to test the terminals on the switch to confirm it’s working properly?
The circuit breaker is mounted under my intermittent wiper switch next to the radio. It has voltage on both sides so I think that indicates it’s OK.
I heard a contact closure clicking out under the hood by my cruise control unit when I applied the brakes. There is a relay (two actually) hidden underneath the cruise control. One clicks (part# FoMoCo C8ZA-9D737-A) when the brake is applied. I see WCCC has this part listed as the Cruise brake release. Makes sense. I’m going to test this unit according to the shop manual procedure. I don’t know where current is supposed to flow, and since I don’t use the cruise, I cant tell if it’s properly cancelling anything. I’m wondering if something in the cruise control might introduce another point of failure like a bad circuit breaker, not letting current back to the tail lights?
I’m not sure what the other “relay” next to the cruise cancel unit is for. There is no part number stamped on it, just yellow wire on terminal 1 and a red wire on terminal 3. None of these seem to pass enough current to illuminate a test light at any point. Photos of the parts I’m mentioning are here
https://photos.app.goo.gl/98F8DQhbA6eXhQDY7
Matti did you resolve the issue I am having the same issue. Power to the brake pedal power to the circuit all turn signals work just rear brake light and rear hazards do not come on
I did notice when emergency flashers are on the dash arrows blink when applying the brake they stay lit and don’t blink?