Headlamp issues

[tr7dan]

So, whilst I am waiting for my viscous coupling bits I thought I would take a preliminary look at the headlight problems.

What I have is, only the left headlamp pops up and down on the main light switch exactly as it should but there's nothing happening on the right. If I disconnect the battery and raise the right pod manually with the knob on the end of the motor, as soon as I reconnect the battery the motor returns the pod to the lowered position, even with the light switch turned off. I guess that at least proves that the motor is working. Nothing happens at all with the headlight flasher stalk.

I need to try to get my head round the wiring and understand how it all works but my first concern is - how the hell do you access the various run/stop relays, pektron unit, etc ? Presumably just working through the hatch at the back of the glove box ? I can't even see how the right hand set of relays etc are connected or fastened in place ?



cheers

Dan

[saabfast]

First, starting with the easy bits, have you checked and cleaned the connectors in the engine bay behind each headlight (two each side, red and black IIRC) and the earth wires which screw into the inner wing?
Next have you stripped and cleaned the headlight switch? Not too difficult but take a picture of how the contacts sit to make reassembly easier. They are normally gunked up with old green grease. I use dielectric grease (silicon grease) on reassembly.
Then, if you need to get to the relays etc. take out the 3 screws you can see which hold the fuse box. It will then drop down below the dash and be a bit more accessible.

[tr7dan]

Thanks for that - I did check each connection on initial re-assembly but I'll go through everything again today as a double check. I did take out the three screws at the back of the glovebox but it didn't seem as if the fusebox/relay assy was loose enough to drop down - maybe just snagged on something, I'll have another look.

[busheytrader]

This small, about the width of a little finger, electrical component may sit amongst the fuse box. IIRC it’s connected the the 2 brown wires in your photo, it’s a fairly lose fit on mine. If that disconnects one wire or drops down underneath the carpet if fitted, neither pod will work as it’s a thermal cutout for the motors.

(Hopefully I got that right, if not your wipers won’t work)

[dursleyman]

Suggest you re-check those connections and earthing points first plus the main light switch.
I put labels on this picture of my fuse box in case it helps anyone.

[tr7dan]

Suggest you re-check those connections and earthing points first plus the main light switch.
I put labels on this picture of my fuse box in case it helps anyone

Sounds like a plan

[FI Spyder]

Bear in mind the position of the components on the fuse box changed several times though out the production run. The only way to be sure is match picture of it by year or consult the OEM service manual. The suggested cleaning of contacts behind the front engine bay, switch contacts will fix most headlight problems. I cleaned the connections in 2007 with electronic cleaner and a small round brush (or pipe cleaner) then applied a thin coat of dielectric grease. The switch contacts I cleaned with Brasso, then dielectric grease so the don't recorrode. Take pictures of switch contacts as they go back in several ways, only one is right. Never had a problem since.

[Beans]

... I did take out the three screws at the back of the glovebox but it didn't seem as if the fusebox/relay assy was loose enough to drop down ...

Depending on model year there is a mounting point for the fuse box in the engine bay (later cars) or two brackets behind the glove box.
But I wouldn't bother with that as the fuse box won't move much. There's just a big chance you dislodge or damage some of the wires.
Picture to illustrate what is hiding behind the glove box ...

[tr7dan]

Ok, so, headlamps now both working as they should. I found it helps immensely to reconnect ALL the wires that I disconnected previously on stripdown.....

Doh !!

[FI Spyder]

Yes, dirty (corroded) contacts are the cause of most electrical problems including gauge problems. Corroded contacts raise the resistance of the circuit giving wrong readings to the gauge be it on the supply side (12V) or the return side (grounds). I've meticulously cleaned all contacts with electrical cleaner and I've only had two problems and both were physical, a loose clamp to red battery wire and no dash lights, a broken 12V wire at the connector going up the dash column to the dash lights. Unlike modern cars with sealed connections (although those can cause problems too) the TR7's are open to the elements.

[Cobber]

So the problem was a high impedance air gap!

[tr7dan]

So the problem was a high impedance air gap!

Ha, yep !

I had inadvertently trapped the single wire with the round black connector behind the headlamp mechanism when refitting and therefore, unnoticed, hadn't fed it through the grommit into the engine bay.

This, of course, left me with two unnconnected wires on the right hand side, one of which I knew was a spare terminal for cars with the expansion tank on the right but, because I had nothing to connect to it, I had assumed the round black terminal was also a spare - perhaps for cars with indicator repeater lights. I should have twigged really because obviously, had that been the case, there would have been a matching spare terminal on the left !

Oh well, I've done a full front to back refresh on the car so far, so I guess I'm allowed the odd brain fart....