In the process of restoring a '72. Replaced the rear bumper and all light sockets, both sides upper and lower. I get good power to the sockets. The tail lights illuminate just fine.

With the headlights on when I turn the blinkers on, right or left, they blink. However the upper light bulb and lower bulb do not flash at the same time and alternate when flashing. Is this correct? Shouldn't both bulbs, upper and lower, flash at the same time?

Also, with the headlights on, when I press on the brake pedal the lower bulbs, both sides, go out. The upper bulbs stay on. I checked the fuses, all good. Bad brake light switch?

Also, when the brake pedal is pushed, should both the upper and lower bulbs light up?

I think have reconnected the wires from each socket to the wiring harness in the wrong order? Any info will be appreciated. Not real good when it comes to electrics.

All front lights and side marker lights work fine.

Thanks,

Will

 

All four bulbs should light up at the same time when you press the brake pedal. There's only one wire coming out of the brake pedal, so there's no physical way for the switch to affect the bulbs differently. If any brake lights work, the switch is fine.

The wire from the brake light switch runs to the turn signal switch, where the circuit splits into two, one for the RH bulbs and one for the LH bulbs. If at least one bulb on either side works, then the turn signal switch is fine.

This leaves the sockets, bulbs, and wires at the bumper as possible sources of the problem. Most likely is that there's a bad ground wire or bad socket connection at one of the bulbs, causing that one to ground through the park light circuit and causing the weird functioning. Be aware that a dirty connection (including where the connector terminals crimp to the wires) could show continuity with a volt-ohmmeter but still have too much resistance to work properly when you try to flow enough current to light the bulb. The other possible problem is where the socket grounds to the tail light housing.

 

Joe, thanks. I'll go back in and see if I can spot the problem. What about the way the upper and lower bulbs blink alternately when the turn signal is on left or right? Should the both the upper and lower bulb blink on the same cycle or at same time? I ver much appreciate your input. Will

 

Yes, they should flash at the same time. The fact that they don't points to a grounding issue.

 

Joe, Thanks. i thought they looked a little funny. I'll start tracing from the bumper forward. I must have done something when I was putting it back together. Will

 

The back lights are grounded through the bumper. If you restored it, is there to much paint on the brackets to where the bumper bolts are not making good ground on the bumper brackets? or brackets to frame? or the opposite, To much corrosion between the bumper and brackets?

 

Its a new repo bumper and I made sure to sand paint off the tabs on the bumper mounts down to bare metal that come into contact with the inside of the bumper. I'll check it again. Thanks, this is all most helpful!