Both mirrors dead

[dmcindiana]

Hey, all.

What should the voltage be at the way top right pin when looking at the back of the mirror switch? I am only getting 4 volts both engine off and engine running.

My passenger mirror LR has been dead as long as I've had the car and passenger UD has been intermittent. Driver always been fine. Switch itself confirmed good by doing a laborious continuity check and mapping out connections. All eight functions mapped and working.

Additional background: I had the roof box access open over the weekend to do a very quick look-around in there. After stuffing the connectors back in and sealing the opening up again, I found I had completely lost the passenger mirror. That's when I did the check of the switch. All functions working. At one point when I had the switch back in, I jumped the left "stop sign" pin to the way top right pin (because I was curious about something I found during my mapping), and that's when both mirrors completely died. #9 fuse is not blown. Two of the eight functions definitely close those two pins (being driver R & passenger R), so I cannot imagine that I damaged anything.

I think the mirror deadness and my jumping experiment are just coincidence, and that I have a terrible voltage-reducing connection somewhere that's in fact always been a problem. Is 4 volts normal? If should be 12, what's the number 1 place to check for corrosion in the mirror circuit? Anyone else have both mirrors die at the same time?

[pk2678]

Hey dmcindiana,

on that page is a nice picture of the back side of the mirror switch:

https://deloreanblog.blogspot.com/2016/04/delorean-mirror-switch-fix.html

On the right you see a pin with a black cable. That's the ground connection (0 V). Closer to you is the pin with a cable of long white and small light green sections. In that view, it would be the bottom right pin. That's the cable which is connected to fuse #9. That should have 12 V. If you disconnect it from the switch and it still has only 4 V, you have to follow the way back of that cable to fuse #9. There are some connectors in the roof box and in the electric compartment and opposite of it. See the roof wiring harness:
https://store.delorean.com/parts/electrical/3-7-1-roof-wiring-harness.html
The rear defogger switch is also connected to fuse #9. If there are only 4 V too, the problem could be located near the fuse box. But that's probably not the case. I would assume somewhere in the roof box.

[dmcindiana]

Pk, this gives me some great next steps. I'll try just pulling the WG wire and rechecking voltage, and I'll check voltage at the defogger switch too. I guess I'll also just see what the voltage is at the fuse box.

I've seen on here that some components don't actually run at 12 volts, and I wanted to make sure the mirror switch wasn't one of those. You are being clear that it's not.

But have you not heard of both mirrors just dying simultaneously like this?

[dmcindiana]

12v at the defogger switch and 12v at the fuse. Still 4v at the mirror switch. For one instant the mirror switch jumped to 12 then back to 4 but it never jumped again after that. Back to the roof connections.

[Bitsyncmaster]

12v at the defogger switch and 12v at the fuse. Still 4v at the mirror switch. For one instant the mirror switch jumped to 12 then back to 4 but it never jumped again after that. Back to the roof connections.

I assume your seeing 4 volts when the motor should be running. Bad connections don't show the voltage drop without a load. Your reading at the fuse and defogger would need the load to be a useful readings.

[pk2678]

But have you not heard of both mirrors just dying simultaneously like this?

No, I haven't heard this before.

There is only this single light green/white wire that supports the 12 V for all movements of both mirrors. If the voltage is not enough, I would assume that the passengers side mirror will stop working first. Because the wires must go from the switch back through the left door, through the roof and down the right door. The wires to the driver side mirror go directly from the switch to the mirror.

--Peter

[DMC-Ron]

I assume your seeing 4 volts when the motor should be running. Bad connections don't show the voltage drop without a load. Your reading at the fuse and defogger would need the load to be a useful readings.

I'm with Dave, perplexed by the 4 volt reading. Is this reading with the mirror switch pushed to move the mirror? And what is being used as the ground (negative) reference for the meter reading? If you indeed have 12 volts at the rear defogger then you need to check with your multimeter for 12 volts between the green/white wire (connection 1) and the black ground wire (connection 2) on the mirror switch. Both the 12 volts and the ground come from the roof box and could be affected by poor connections there. Still, the 4 volts reading is odd.

Ron

[dmcman73]

A quick test of the mirrors to confirm if the motor inside them is working or not would be to apply 12v and ground to the connector coming off it under the door card, this would bypass all of the harnesses and the switch.

Applying 12v to the White/Brown and Ground to the white/red wires on the connector should cause the mirror to move either right or left. Reverse the voltage on those two wires and it should move in the opposite direction. If the mirror does not move when applying voltage to those two wires directly at the mirrors connector inside the door, then the motor is dead. If the R/L motor does move, you have a bad connection in the harness somewhere, possibly in the roof box, causing the issue. You'll need to trace it with an Ohm meter to find the break.

If you want to test the up/down motor the same way, apply 12v to the White/Purple and ground to the white blue, it should move it either up or down, reverse the voltage between the two wires and it should move the opposite.

For the drivers side: Apply 12v to White /Purple and ground to the White/Green wire on the drivers side mirror connector to move it up/down then reverse the voltage to confirm it moves in the opposite direction. For the left/right on the drivers side, the wires are white and white brown.

Just make sure you unplug the mirrors from the harness before applying voltage to them.