I have a 1966 Fiat 500F. I bought a new rear view mirror for it. When I plug the positive (white) wire into the plug labeled with a + the light in the mirror comes on. I can flip the switch on the mirror but the light does not turn off. Did I get a mirror with a faulty switch or do I have some sort of short with my wiring? What the heck is going on here? I would think that once the switch breaks the connection it should turn off but that's not happening.

Autob,

I have a 69F, it has a switch in the door jamb and two wires at the mirror. This allows the switch on the mirror to turn the light on all the time or on only when the drivers door is opened.

If you only have one wire I suspect you have an earlier 'F' loom and don't have a switch in the drivers door jamb that also turns the light on and off when the door opens.

It therefore should be simple (but we are talking about a 500!) as you say. Switch on completes the connection, switch off breaks it.

Did you replace the whole mirror? I am wondering if you have a newer light on an older car. Does the small connector at the top af the metal frame of the mirror have two holes for wires? Perhaps a photo or two of the assembly will help us.

Regards

Joe R

Thanks Joe,
I didn't think about the door switch so that could explain why the light would stay on but, unfortunately, it doesn't. I installed the new mirror. It does have two wires going to it, black and white and two corresponding plugs. the light comes on when I plug in the wires and doesn't go off even when the door is closed or the switch depressed by hand. It also doesn't turn off when I flip the switch on the mirror. Of course I have unplugged the wires since I don't want to drain the battery. I can send a picture if it would help.

AutoB,

When was the last time this worked? What has been done since then?

Looks like you have a permanent earth connection.

Mine is a RHD car but I suspect that the light is the same. This is how it connects and works on my car.

From the drivers seat the switch is to the left side of the mirror and the bulb on the right. A no brainer really, the actual workings will only fit in in this way.

I have a purple wire going to the fuse box and a black wire going to the door switch. The black wire connects to switch side of the assembly, the purple to the bulb side of the assembly. I think it its important that this is correct.

(For clarification I think my purple wire is your white wire and the in reality the wires plug into a little plastic plate that sits in the top of the mirror frame.)

With the switch flicked to the left the light stays on all the time (door opened or closed) Here the earth is coming throught the metal mirror frame directly.

With the switch flicked to the right the light stays on when the door is opened, but goes off when the door is closed. This should be the position the switch is in by default. Here the earth is controlled from the door switch.

If your wiring at the light looks OK then I suspect that the door switch may be an issue. Perhaps you should unscrew it and have a look.

Mine was rusted so badly there was no bright metal to make a good earth contact. Yours may be broken and fused together so you get a permanent earth connection.

Be careful when you unscrew the switch in the door. If you are not careful and you pull the wire off the back and it falls inside the door jamb it is a bit of a bugger to fish it out. It can be done with a piece of wire with a hook on the end of it and a torch.

Regards

Joe R

Use an ohmmeter to check the mirror switch when not plugged in. Measure the resistance between the two mirror wires with the switch in both positions. The resistance should be infinite with the switch in the off position, something finite in the on position. Sounds to me it is a bad switch that is in the on position all the time.

Thanks, I replaced the mirror with one purchased from Ricambi500 because the original was in bad shape and the light part of it was damaged and didn't work. I still haven't figured it out but will tinker with it today. I appreciate all the helpful comments on this forum - sure takes some of the mystery out of things!