Indexing Rear View Mirror, no worky

[noz]

I'm having problems with the nearside mirror. It's supposed to tilt downwards when reverse gear is selected to afford a better view of your back bumper. It's also supposed to return to the original position once reverse gear is deselected.

For a while now it has been tilting when in reverse but I've had to correct it manually. Now, however, it stays tilted downwards permanently. I try to correct it when not in reverse and although it does right itself, as soon as I let go of the adjuster switch it just tilts back down again. It's almost as if it thinks I'm permanently in reverse.

Does anyone know where the 'box of tricks' is? Presumably there's a brain which receives the same signal as the reversing lights and adjusts the mirror accordingly. The strange thing is that the nearside mirror has the same number of wires as the offside so the 'box of tricks can't get any feedback. Presumably it does it based on time. A fixed time to tilt downwards and a fixed time to tilt back up again. This of course presumes that the mirror moves the same speed in both directions and hence returns to the same place.

I don't find the feature useful at all and would gladly disconnect it if I knew how.

Any thoughts anyone?

cheers

noz

[Peter N]

Hi Noz

I would have thought that rather than use a seperate switch it would be activated by the reversing light switch, I suppose your reversing lights are not stuck on? or that both bulbs have not gone?...just a thought, in the absence of a circuit diagram.

Peter.N.

[noz]

Aha, found the problem.

I wondered how the controller knew which way the mirror was facing and how to return it to it's original position.

Now I know. Each of the two little drive motors have potentiometers built in and they feed back to the indexing controller which is fixed to the inside of the inner door skin.

I measured the resistances of the pots from the controller end and got nothing. I traced the wiring all the way back to the mirror itself and the continuity of the wires was OK. Finally I stipped the mirror down and measured right at the terminals of the motors. No joy.

Luckily I had a spare (second hand) motor assembly in stock and I measured it to see what it should be. It worked fine.

Now to swap the motor assemblies. The second hand one was unceremoniously ripped from a scrap car so had none of the plugs on the ends of the cables. So I de-soldered the wires on the back of the motor assembly. It got too dark last night to resolder the new one on so that will be tonights job, rain permitting.

I'll get back when I'm finished hopefully to report a working mirror.

Cheers

Noz

[noz]

Update:

Desoldered the old mirror assembly and resoldered on the new. Working like clockwork.

As usual, the job's easy, the hard work is in the diagnosis.

Hope this helps someone else.

Cheers

noz