This one really has me stumped!

[BJ8Healeys]

Spridgeteers, this problem has me really stumped. I hope someone can recommend something I haven't already tried.

1. I am reassembling the car ('73 Midget Mk III) after a total repaint.

2. During disassembly, the molded plastic connectors in each of the headlamp harnesses crumbled, so I replace both harnesses with new ones from Moss.
3. Because the headlamps were mis-matched and the left side high beam wasn't working, I replaced both headlamps with new ones. (NOTE: the left lamp high beam did not work in the car (with the old harness), but I just tested it directly to the battery and both beams worked).

4. I drove the car to a location where I could adjust the headlamp aiming according to instructions at danielsternlighting.com. Both new lights worked on both high and low beams.

5. When I finished the aiming procedure, I turned off the headlamp switch before starting the car to drive home. That's the last I have seen of either the high or low beams of either lamp. Fortunately, it was not too dark to see and less than a half-mile down a neighborhood street to home.

6. I have checked the headlamp wiring end-to-end per the BMC wiring diagram. With the headlamp switch on, I have 13 volts at all locations checked: headlamp switch blue wire to turn signal switch (power input), turn signal switch blue/white wire (high beam circuit), turn signal switch blue/red wire (low beam circuit), 13 volts to both circuits at the headlight connector of the new harness (since neither light is working, I am only troubleshooting the right one so far).

7. Continuity of ground at the headlight connector.

8. The light burns brightly if I connect either high or low beam terminals and ground directly to the battery. I also plugged in both the old bulbs to the new right side connector, for what that's worth, and neither of them worked.


So, the new light is good, I have 13 volts at both high and low beam terminals of the new harness and continuity of ground. I also can measure 13 volts on the lamp terminals with the lamp connected to the harness connector. What is the problem?

Thanks for any suggestions!

Steve Byers
Havelock, NC USA

 

[Bayless]

It sounds like you have tested the lights and they are all right. Also, you have 13 volts at the light connectors but still no light. The problem is high resistance somewhere in the circuit that robs much of that voltage. Could be a broken or corroded wire internally (not very likely) or a corroded connection at the fuse box (more likely). But the most likely by far is still a bad ground, particularly on a car that has just been painted. And testing with an ohmmeter isn't adequate because so little current is involved. You need some significant current for the resistance to show up.

 

[Gerard]

Steve,

I haven't seen your name in a long time!

Do you have good grounds at all four corners? That's usually where these light circuits fail. The stalk switches and especially the light switches can get pretty flakey with age, so make sure the internal contacts are clean. The light with is particularly prone to over heating, so once you sort out this issue, I also suggest you add relays to the light circuit. The light switch itself is easy to disassemble, so examining and cleaning contacts is pretty easy.

 

[BJ8Healeys]

The problem was a bad ground wire to the right front side marker light. I soldered a new bullet connector to the wire and all is well. Since both headlights have individual ground wire connections, it seems strange that a bad ground at the side marker light could prevent BOTH headlights from illuminating. That's something to consider at speed on a dark night.

Hi, Gerard. I remember your name, too. I haven't been active on the Spridgets forum for many years since most of my time is spent on the Healey side and the Healey BJ8 Registry keeps me pretty busy. I haven't been driving the Midget much during those years for various reasons, so problems and questions haven't come up until recently. Thanks for remembering me.

Bayless, you were correct about the general problem. Thanks for the input.

 

[Bayless]

Glad to hear you found and fixed it.