348 348 headlight problem

My left headlight goes up but not down electrically. I have to rotate the knob to get it down. I’ve read though several posts and I’m thinking maybe that contact disk is corroded in the motor but here’s the thing. It started working correctly on its own then quit again. Where should I start investigating first?

 

Could be a few things, I guess. Diodes, broken contact fingers or corroded disk. Do you have to rotate the knob the whole way down?

You may be able to check the diodes at the relay sockets with a multimeter (if you can't access the motor power/control connectors. The wiring is probably fairly ancient, so you may not be able to identify wire colours.

(EDIT: I don't think it's a relay problem as the power relays are supplying power to lift the headlight. The control relay "A" would affect both headlamps.)

 

You can try swapping the relays "h" and "i" in the luggage compartment fuse box. If the non-returning function moves to the other side, than one of the mentioned relays is bad.

 

Thanks guys.

 

How do I open this up?? Almost looks like it was riveted. Ground off the protective coating and there are no screws holding the back plate on.

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Typically the back plate is riveted on. You have to drill them but then you've got other problems when you reassemble, need to drill and tap and use screws etc.

 

Did you find the external diodes? Can you check those before you start pulling the case to pieces?

The circuit will look something like this:

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The position of the switch depends on what position the pod is in, although that's going to be difficult to know now that you've already removed the motor.

Did you do any of the steps recommended?

 

Yes I swapped the relays. No luck.
I don’t know where the diodes are.
The motor was manually turned all the way down before I removed.

 

I believe they are buried under the sealant on some cars. Miro posted this photo:

https://www.ferrarichat.com/forum/posts/143933085/

You should be able to test at least one of the diodes at the connectors (without removing the sealant) with the pod fully retracted. I'm more worried about the other diode, though.

 

Thanks Qavion.