Brake Lights and license plate light don't work.
I have a 1967 Pontiac Tempest 4 door. My front lights/ dash and tail lights / signal lights/ reverse lights all work. My brake light and license plate light don’t work on car. They used too. My hazards work only in the front of car not on the back of car. When I press the brake while the hazards is on, they stop blinking, that’s the hazards. If I release the brake pedal they blink on and off. I test the brake switch with digital multimeter and the switch is good when pressing down. Why do the tail light work and the brake/ license light don’t? Can someone give some advice before I send her to the shop please.
I would greatly appreciate any and all the help I can please!
Thank you very much.
I would check for corrosion in the bulb sockets and check grounds. You also may want to replace the flasher sending unit to see if that is the problem.
Check the plug where the rear harness plugs into the main body of the car. Sounds like either a bad ground or positive connection that feeds all the lights back there. The hazards stopping their blinking when you step on the brake pedal is normal. HTH. -Jim
Mark, Thank you very much for the feed back. This weekend I will try everything that you told me to do. I really appreciate everything!
How to find a bad ground in the back of the car or positive connection? I check the front of the car and it's ground very good. Thank you very much.
The connector I'm referring to is either behind the back bumper or inside the trunk. Most likely on the driver's side behind the trim panel. I'll check my '67 Fisher Body Manual to see if it shows where the wiring harnesses are. HTH. -Jim
Thank you so much for all your help.
You're welcome. Glad to help. -Jim
I'm back with the same problem above. I tested the light with a digital multimeter and I do get current from the brake lights. Like I said before, the tail light, signal light works. Not the brake light when I apply the brake or license plate light. When I put the hazard light on again the front works, I notices when the hazard light are on the dome light inside of car blinks a little . I also notices that the head light flicker a little. I have a new alternator, battery installed. Fuse are good and nothing blown. I don’t know what else to try. Help please.
Now we're getting somewhere! That's a bad ground. You'll have to determine what is all on the circuit and where the grounds are. Make sure they're clean and tight. HTH. -Jim
Mark, Thank you for all your help. I do appreciate all the advice I can get. I notice a ground strap hanging on the fire wall not connect to anything. I notice it broke off on the other end from something. Should I buy a new ground strap and reconnect it to the fire wall, then to the engine? I never put on ground strap on a car before. Can you please give me advice on putting a ground strap on a car please. Thank you Arty
Thank you very much Jim. I notice that a ground strap from the fire wall is hanging off without begin attach to anything. should that strap be reconnect to the engine? I have been looking to connect it to something, just not sure to what. Can you please tell me where to connect it too.
You're welcome. Glad to help. Yes, you should have 2 ground straps. Both connect from the engine to the firewall. There's one bolted to the back of each head on the engine on one end and the other end slides onto a connector on the firewall. There's a connector on the driver's side of the firewall and a connector on the passenger's side of the firewall for these ground straps. HTH. -Jim
Jim Thank you very much for all the information. Jim, I’m not a mechanic in any way. I have been learning how to do work on my car by looking it up on the inter net or asking question, paying other to do work on car. This weekend I will put on the ground strap on the engine block like you said. Question, if that don’t resolve the brake and license plate lights to work, is there any other suggestion before I send to the shop? Thank you for all of your help. Arty
Definitely hook up those engine ground straps and test the lights. Then look for faulty grounds behind the back bumper. These bulb sockets are grounded to the chassis. For the brake lights you should have bulb number 1157 in there. The two dimples on the bulb are both positive (+) and the socket shell is ground. Make sure the bulbs are in the sockets correctly as well. The two "nubs" on the side of the bulb are offset and designed to go into the socket only one way. Sometimes people would force them in then the bulbs won't work correctly. You can also put some Vaseline on the metal part of the bulbs then insert them into the sockets. This will insure that you have a good connection between the sockets and the bulbs. You can also remove the sockets and clean up the areas where they contact metal. This is how the sockets are grounded. Some GMs of the era also had a pigtail wire on the negative (-) battery cable that must be bolted to the front fender for proper grounding as well. HTH. -Jim
Mark, Thank you very much for all of your input. I greatly appreciate it! Last night I was checking the brake lights when I got home. I notice that when I touch one of the socket that the bulb went out on the right side facing the back of the car. I screwed the bulb back into the socket and notices some play inside of the socket and when I tried putting it into brake light lens. it went out. I wiggle the wire and it came on again. One thing I am going to do this weekend, is order new socket / bulbs to put in. Ground the engine like you said and hope for the best outcome that everything works fine from there on. Again, I thank you very much for everything. I’m sure you will be hearing back from me about the result and progress I make. Thank you very much.
You're welcome. Glad to help. Definitely keep us posted! I really like these old GMs. I've had several '60s era Cadillacs and two '70 Pontiac Catalinas myself. They're great cars!! -Jim
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