A quick intro: I had a TR6 for about ten years, and was a regular visitor to the TR Register forum, mainly to learn stuff. I sold that in 2012, as the wife hated going out in it, and we got a Stag instead. We then emigrated to Perth, Australia, in 2014, bringing the Stag with us, and it is still a member of the family.
Recently we happened to walk past a house where there was a yellow TR7 with a For Sale sign. Having had no intention of getting another classic car...we ended up buying it as the seller was deperate to get rid of it, and I hope the price was right. It needs a fair bit of cosmetic work, mainly trim, new seat foams and sorting out a few electical niggles, but the engine, gearbox and drive train seem fine. It has new hoses, radiator and brakes.
So, to the point of my post: the off-side headlamp pod doesn't rise more than about an inch, and it doesn't drop back either. The near-side works perfectly. The light itself is fine. I have cleaned the earth and red plug contacts, and swapped the relays to no avail. However, I did notice that the circuit breaker was very hot, and clicking, and this resolved if I disconnected the red plug by the headlight. The pod does not rise if I turn the manual knob, and this knob is very stiff, so I am assuming the problem lies in the motor or pod mechanism somewhere. I can raise the pod fairly easily by pulling it up (when the light master switch is on) so I think the mechanism is OK and not jammed.
Would you agree that the problem is likely to lie in the motor? I don't want to remove the whole pod unless I have to and as I am not a mechanic/electrician I appreciate any advice before I get out of my depth!
No doubt this will not be the last question I have to ask here.
Visit this site for a lucid explanation of what the headlights are thinking: http://www.team.net/.../headlights.htm
It usually a bad diode, bad relay, or perhaps a bad switch in the headlight motor assembly. You can test them without removing the headlight by disconnecting the harness inside the engine compartment behind the offending headlight. Use a schematic, all the wires are nicely color coded. There is a nice schematic, by the way, on the referenced web page.
1. Swap the relays in the glove box between the two headlights. You said you already tried this, so you have completed step one, and ruled out the relays.
2. Disconnect the harness to the headlight assembly. Probe the wires going to the motor assembly using the diode test function on your meter. The diodes should read roughly half scale in one direction (or 0.7 volts if your meter reads out in volts while testing diodes), and open in the other. Beware that the diode can act very flakey, and your meter can show it as good, but it will fail when hot, or under load. But it is a good first check. Be sure to test both diodes in both directions.
3. If the diodes pass, repeat the test with the headlight in the up position (harness still unplugged).
4. If your diodes fail open, remember that the motor switch can also fail open, so when you open the motor switch assembly, restest the diode and the switch.
I had a diode fail open in one of my headlights, and it went intermittent before failing completely. When a diode fails open, the motor stops getting power while raising or while lowering, depending on which diode fails (there are two per motor). If a diode fails shorted, the headlight cycles continuously until you disconnect the plug.
I am pretty sure you will end up pulling the headlight assembly to fix it. The good news is that it is trivial.
Keep us posted.