SQLGuy

Hi folks,

One other little thing I'm trying to figure out - when I got the car, the seat and mirror memory system didn't work. I eventually traced this down to the memory switch, in the door, having been installed incorrectly. Once I reattached it properly, the memory system started working... except for the DS mirror. The DS mirror stays where it was pointed when holding down one of the memory buttons, while the other mirror, and all the seat adjustments, move to whereever they are supposed to be.

I've removed and reseated the three connectors from the mirror memory unit, so no easy fix. I expect the problem is most-likely in the mirror memory unit itself, as the mirror would be more likely to fail for only one axis... but just wondering if anyone's dealt with these symptoms before.

Edit: BTW, for troubleshooting, can I switch the PS and DS mirror plugs at the mirror memory unit and see whether the problem switches sides?

Thanks,
Paul

Mrmerlin

with memory issues the problems are in the switches or the CB under the driver seat, resoldering the CB can cure lots of problems

SQLGuy

I've already had the CB out, when I did the original investigation about the miswired control switch. The solder joints in it were in very good condition. There are also only two connections to the mirror control box (next to the clutch pedal) that are fed from the under-seat unit; they are power and ground (30 and 31) - so no logic/signals between the units. I don't see how this could be caused by the under-seat unit.

What about the switches could allow you to set and select a memory position, move both mirrors manually, but not have one mirror realign itself from memory?

Thanks,
Paul

SQLGuy

After further investigation, I am pretty sure it's the mirror control module. My reasoning for this is that, when I move to memory position 2, the DS mirror will move, and it seems like the controller is never happy with its position, continuing to try to move the mirror up and in. When switching to positions 1 or 3, whether or not the mirror has been manually moved in between, the controller doesn't move the mirror at all.

Maybe the controller was damaged by the incorrectly wired switch.

I'm tempted to shotgun the CMOS multiplexor and the ADC, since those I can get, and I'm quite sure I can't get the microcontroller. The multiplexor and ADC are also the first things the buttons seem to go to... though I'm still not seeing where exactly the signal from the 1/2/3 buttons goes.

In case you're curious, here's what the inside of the mirror memory module looks like:

SQLGuy

Well, the position number line goes through the 22K x 7 resistor network to form part of a voltage divider that then runs through the multiplexor to the ADC.

The fact that the DS mirror seems to work correctly makes me suspect that one or two channels of the multiplexor may be blown. I think I'll try swapping that and see whether anything changes.

Just in case, anyone have a spare one of these modules they'd be interested in selling?

Cheers,
Paul

SQLGuy

Well... got my new CD4052 (CMOS multiplexor) in today, swapped it in, and... no difference.

Since:
1. all manual mirror controls work correctly = not motor controllers or motor wiring
2. memory setting works correctly for the PS mirror = not the single ADC that's used for everything
3. DS mirror pot values seem reasonable when read by DMM from the mirror module connector and it does move in one memory position (though not correctly) = probably not the DS mirror itself

I'm guessing there's something actually wrong with the microcontroller. I guess a replacement module will have to be the next step.

Cheers,
Paul

SQLGuy

I got another mirror memory unit, used, but still have more-or-less the same problem:

Driver side mirror doesn't move at all for positions 1 or 3, regardless of where it is before activating the memorized position.

For position 2, it does move, but not to the correct adjustment position.

Manual settings work correctly.

Passenger side mirror works correctly for both manual and memory use in all positions.

Seat moves correctly for all memory positions.

----------------------------------------------------

I thought that this must be an issue with the mirror controller, since the behavior is different for different memory positions, but the memory positions work correctly for the seat. Either I have two bad mirror memory units, with pretty similar failures, or....?

Any ideas?

Thanks,
Paul

mickster

So let me get this sorted in my head (having not worked on this):
1) Controller (aka the buttons) in the door:
a)Button 1, 2 & 3 move the seat to the correct memorized position
b)Only Button 2 moves the mirror to the wrong memorized position
c)Swap-out of controller leads to same results
d)PS Mirror always works correctly

2) Leads me to believe the problem is at the DS mirror-not the controller-why? Because the DS mirror MUST be giving feedback as to its position to the controller to tell it when to stop and the manual control switches move as expected; since feedback results are similar, ergo DS Mirror feedback, ergo DS Mirror "sensors" or whatever measures position

3) Still could be bad wiring in the manual electronic mirror control---assuming signal passes through that switch and on to the actual mirror...less likely since PS mirror works correctly

Michael

SQLGuy

Hi Michael,

No, controller is not the buttons in the door. Controller is the unit pictured a couple of posts up. It controls the motors and memory for both mirrors. The buttons in the door send a resistance signal to both the mirror controller and seat controller to tell them which buttons have been pushed.

I agree that the pots used to send positional information, in the DS mirror, would be the next suspect, but that doesn't explain why the mirror only moves when position 2 is pressed. If I set position 3 to the position 2 setting, it's still only position 2 that causes movement. The mirror itself has no information about what position button was pressed.

BTW, manual control goes through the mirror control module as well. It's just that the motor controllers are getting their signals from the joystick in the door rather than from the microcontroller in the controller module.

When I was in there before, I measured the positional signals, at the controller, for both mirrors and got similar readings - so no broken wires there. I did not measure them at different positions, so I will probably try that, but I'm not that convinced it's the mirror.

mickster

Yeah--I just read through the Service Manual and saw how the system works and where to check what...

Have you ruled out the switch set itself? (swap leads from 1 or 3 to position 2?) I think you did...

Michael

SQLGuy

I haven't swapped leads, but the symptoms basically rule out the switch - since the one switch is used for both seat and mirror memory, and since the seat and one mirror work correctly, it doesn't seem possible that it could be a problem with the switch.

Mrmerlin

if your careful take the left right switch apart there is a little barrel in there, and its pressed into the leads by a spring thats on the central shaft of the rocker .

Put a towel down before you try to open it so the spring/ barrel wont fly off .
the barrel is held by 2 little fingers of plastic so it doesnt take much for it to come flying off a pencil eraser should clean the barrel and the contacts inside the switch

mickster

Have a look here:
https://rennlist.com/forums/928-foru...e-mirrors.html
https://rennlist.com/forums/928-foru...lem-87-s4.html
https://rennlist.com/forums/928-foru...estions-2.html
https://rennlist.com/forums/928-foru...-properly.html
https://rennlist.com/forums/928-foru...mlin-pics.html

I'm starting to think it's either the 3 selection controller or else the under-seat connections since the controller has been replaced...

The WSM begins on 72-7 for checks and such...pretty straightforward...

SQLGuy

Hi Stan,

As far as I can tell, the changover switch is only used for manual control and not for memory repositioning. Since manual control works fine, I'd rather not open up that switch. Can you help me better understand why you think this problem could be caused by the changeover switch?

Thanks,
Paul

SQLGuy

The three position switch for selecting memory is shared by both the seat controller and the mirror controller, and doesn't distinguish left or right. Since all three positions work correctly for the seat and for the right mirror, I don't think this could be the area of the problem.

As for the under-seat unit, the only connections between it and the mirror control module are the 1/2/3 signals from the memory switch, power, and ground. Again, nothing that differentiates left from right behavior.

Cheers,
Paul