Bill Ball

Alan: Will do. Thanks again for everyone's input. I'm sure you have located the problem area.

Mrmerlin

Bill any updates??

worf928

Bill, when you disconnect the door harness to begin checking out the door wiring you can check the voltages on the controller's side of the door harness plug with the window switch in its three positions. If the voltages make sense e.g. 0, 12v, and -12v, then you have reason to continue into the door. If you get similar whacked voltages on the controller side of the plug then you work the other way.

Of course, if you have the battery connected, the door harness disconnected and the window still goes down, you'll need a fire extinguisher and a priest.

Bill Ball

I was away all day. Busy tomorrow with other cars too. Probably Monday. After that, maybe you can help me figure out why the AC blower motor keeps blowing fuses!

Bill Ball

Thanks, Dave!

Mrmerlin

any chance the blower harness is caught between the hood and the cowl seal?

Bill Ball

OK, I'm back after doing some investigation. Very confusing.

I took off the door panel and unplugged the window motor. Here is what I found.

The GR/BL from pin 33 to the passenger side window motor has 12V resting. The GR/BR wire from pin 35 showed ground. So, the motor would go down. If I disconnect the white plug at the controller, the GR/BR still shows ground. I noticed that the GR/BR is joined to a wire that goes the sunroof motor. I ran the sunroof motor back and forth a few times, and the window started working normally. However, a minute later the passenger window went down on its own again. When it was working OK, I think I measured 12V on both of the leads to the window motor when at rest. Is that normal? So something is taking the GR/BR wire to the window motor to ground and I think it might be related to the sunroof, but what?

Ed Scherer

Bill, I haven't read through this thread very thoroughly, but years ago, I experienced some extreme weirdness on my '90 S4 after replacing a window switch that was the wrong type. Read about that experience here:

Nichols tip 532: Power Window Switch Info

Anyway, my point isn't that you're experiencing the same thing (you're probably not, assuming you haven't replaced any window switches), but that the window/sunroof stuff is interrelated in strange ways, probably mostly due to the fact that they're sequenced (if you attempt to operate one of the switches when the previously-requested operation isn't yet complete, etc.) and the "auto-closing when you hold the door lock in the locked position for awhile" feature. Furthermore, I suspect that the controller uses sensing of motor current to determine when one of those devices has reached its limit of travel.

With that in mind, there's probably lots to go wrong, and a problem on any of those three motor circuits (not to mention the switches, which I think you might have already eliminated as the source of trouble, but I'd still suggest disconnecting them all when diagnosing this problem) might influence the others in strange ways (unless you have a deep understanding of how the controller really works, which I don't).

I'd probably check all the wiring to the sunroof and window motors: continuity, ability to flow current (maybe with a purely resistive test load), and none shorted to ground.

Bill Ball

The behavior happens with the window switch detached. But I'll detach all of them and probably also pull the drive door panel and detach that harness plug.

What should I normally be seeing at the window motor plug when resting? 12V on both sides, zero volts, or ground on both sides.

Alan

Bill - Actually Ed has a good point - and you may be right about the sunroof interaction.

Understand that all the motors share a common connection on one side and have a unique connection on the other. When one motor runs one or the other of its motor connections gets grounded by an internal relay in the controller. If its the common side connection that gets grounded then all the unique connections for the other motors are also grounded at the same time (or else they would also run).

Try disconnecting the other motor connections and see if it makes a difference...?


to Ed - yes it senses the stall current spike to turn off - though it also has a timeout. I think Porsche had problems with the stall sensing with multiple motors running - which is probably why its configured as it is (sequential only).

Alan

Ed Scherer

I'm not promoting "edatching;" merely trying to edify.

worf928

BB, does this car have after-market 6" speakers?

Regardless of answer, the FM says that the 6-pin T42 connector is in that area (passenger side)- likely behind the 6" speaker or accessible once the speaker is removed. T42 connects the sunroof into this whacky circuit for the windows and controller. Given your sunroof observation I'd disconnect it at T42. I'd also disconnect the entire door harnesses under the extreme corners of the dash. With the door harnesses and sunroof harness disconnected, you should be able to isolate the behavior to a single harness.

Alan

Bill - does the sunroof work? do any of the other motors do any jiggling when the drivers window moves - or the opposite. I assume you had some specific reason for suspecting the sunroof...?

BTW Ed - since you are reading this - am I right in thinking you have an AIR wing -and that you have installed an LED brake light into it? if so can you send me some pics of it? Looking to do similar - I have a fiberglass Strosek 'like' wing - but its not in very good shape - I may start over...

Alan

Bill Ball

Here's what I see now. All window and the sunroof switches are disconnected. With ONLY the white plug (pins 31-38) connected to the controller, I see 12V coming into the controller on pin 37 (RD/BK wire) as it should, and I see 12V going out on pin 33 (to the passenger window motor) and its jumper to pin 38. This is at rest. Neither the driver door window motor output (pin 34) nor the sunroof motor (pin 32) power outputs have 12V. They all share pin 35 ground.

Now, if I connect the driver door switch and connect the brown and black plugs to the controller, none of the above changes, but when I push the driver side switch DOWN, pin 34 goes to 12v and that window goes down. If I push the switch UP, pin 35, formerly the ground, goes to 12V. I didn't check to see if pin 33 then goes to ground, but I would guess it must. So, it appears to me the way the system works is that the switches reroute the power output and ground to opposite pins via relays.

So, other than the power input, I don't think any of pins 31-38 should be 12V at rest. But something is putting pin 33 at 12V, so the window goes down. I don;t see how it could be the controller, as 2 of them are doing the same thing, and neither of them did this before. This all started a couple of weeks ago.

I suppose I could make a jumper wire between the power supply line and pin 37 and see if pin 33 goes 12V, with nothing else connected (in which case blame the controller), then connect the other 31-38 wires to the controller one at a time until pin 33 goes 12V.

FOLLOW-UP ON THAT LAST IDEA:

OK, so I jumpered power to pin 37 on the controller. Pin 33 is fine, BUT as soon as I connect pin 33 on the controller to pin 38, as it is in the wiring of the plug, 33 goes to 12V. So, pin 38 has 12V all the time. What does pin 38 do and why does it only go to pin 33?

FURTHER FOLLOW-UP ON PIN 38:
I cut the wire to pin 38. All the windows and sunroof work fine now, EXCEPT they no longer work when the ignition is off. So, pin 38 was probably providing door pin switched power. Anyone want to continue with where to look now? The door pins seem to work properly. I'll try to deduce the circuit connections.

Something is supposed to drop pin 38 from 12V and is not doing it or something is feeding it 12V via a short. Where????

no doubt

On my 88 S4 the windows/sunroof will work after you turn off the ignition *until* you open a door.

Is that behavior controlled by a relay or ECU? I'd look to that relay or ECU for your 90.