Question: Driver's headlight not lighting

[Dsrtknight]

History: Alternator failed on me and had it replaced. Prior to replacing the alternator, I noticed that the driver's headlight low beam was not working (delayed fixing this until alternator was replaced and battery was charging). I bought two replacement headlights for my C4 1987 Convertible and replaced the left side first. After replacing the headlight, the light worked fine. By the next day, the light was no longer working.

My thoughts:
1. I did not secure the light fully and the connection has jiggled loose
2. While alternator was going bad, it caused damage to the fuseable ink for the driver's headlight (I believe this is under the battery but haven't confirmed)
3. Wire short (I inspected the wires and found no damage)

Is there anything I could be missing? The passenger side headlight works fine, both headlight motors work fine and everything else seems to be working fine.

Is there a fuseblock for the headlights (I haven't found any fuses for headlights and would like something as simple as a replacing a fuse).

Thanks

 

[Hot Rod Roy]

I would suspect that your '87 headlight wiring is the same as my '84, but I could be wrong. My '84 FSM wiring diagram shows the two headlights are wired in parallel, directly to the dimmer switch. There is only one circuit breaker for the two headlights, which is at the headlight switch. They do have separate grounds to the chassis, though. You could check the 12 v to each headlight at each connector. With the headlight switch on, you should have zero volts at the ground terminal of the headlight. If you have 12v at the ground terminal, you have a bad ground connection.

It is possible your new headlight is bad.

 

[Dsrtknight]

Problem solved

I would suspect that your '87 headlight wiring is the same as my '84, but I could be wrong. My '84 FSM wiring diagram shows the two headlights are wired in parallel, directly to the dimmer switch. There is only one circuit breaker for the two headlights, which is at the headlight switch. They do have separate grounds to the chassis, though. You could check the 12 v to each headlight at each connector. With the headlight switch on, you should have zero volts at the ground terminal of the headlight. If you have 12v at the ground terminal, you have a bad ground connection.

It is possible your new headlight is bad.

I pulled the 'bad' light and swapped it with the working light and it worked fine. So, I backtracked from the headlight to the fuselink and there was the problem. Somehow, the fuselink was just loose enough to lose contact. The hood light had come loose as well. So, I fought with the fuselink (it is connected to the car body) and finally got it reconnected. So, I have a new set of headlights, possibly tighter connections and a spare working headlight to boot.

 

[Hot Rod Roy]

Somehow, the fuselink was just loose enough to lose contact. So, I fought with the fuselink (it is connected to the car body)

The fuselinks are never connected to the car body. They are near the battery in the 12v supply circuits. Exactly where did you find the loose connection?

:cool

 

[Dsrtknight]

Loose connection

The fuselinks are never connected to the car body. They are near the battery in the 12v supply circuits. Exactly where did you find the loose connection?

:cool

After disconnecting the battery, I backtracked from the headlight to the fuselink, I followed the bundle from the headlight connectors through the opening in the headlight door body, down to the connections for the hood interior light, door motor and light connections. I found that the headlight connection was not fully seated/locked. So, I pushed it together as best as I could. One challenge was that the connector from the headlight is connected to the body with a plastic clip. I had to remove it from body, to get some slack on the connection, and reconnected. Then the interior light connection became unconnected (it is a tight fit and further down in the well). I again pushed the connection together and reconnected the battery (the hood interior light came on). I pulled the light switch and the light came on but the headlight door wouldn't rotate. So, I disconnected the battery again and checked all three connections and made certain that the headlight bundle wasn't getting pinched in the opening of the headlight door. All works fine now, but the connections are tight and I suspect they have a habit to come loose. I think it might be time for me to check all my connections and ensure they are tight, so I don't get a surprise while driving.