glack

Anyone have any ideas on this:


Car: '85 Euro S
Subject: 4-way (fore/aft-front up/down) passenger seat switch replacement turns awry

Here goes:

1. Face of said switch was broken off some time ago.
2. Screwdriver was used to move seat forward two times.
a. On second occasion, seat switch broke in "on" position. Motor of either fore/aft or up/down motor was stuck on until fuse went.
b. Smell of burned electrical component came and went briefly

3. Removed seat today.
4. Replaced broken switch with brand new switch from 928 Intl.
5. Replaced fuse
6. Upon installation only up/down direction of switch worked.
7. Tested fore/aft motor with power from seat's own power plug.
a. Motor spun freely
8. Checked power in fore/aft motor switch connectors with 12 volt tester (car off).
a. Got varying results (with car remaining off); tester bulb went from very dim to non-existent in the forward direction; tester bulb was very bright to slightly dim in the reverse direction
9. Checked power in up/down motor switch connectors; tester bulb was very bright in either direction
10. Used power connectors from up/down motor on fore/aft motor; no movement

Bad switch and bad motor combo?

crackerfeet

When you did No.10 did you use the up down switch also?

glack

Not until you suggested it.

I switched the connectors for each motor and it worked (in directions reverse to desired input), for about 1-2 seconds. I attempted to switch the connectors on the respective motor to reverse the polarities, but now it no longer functions.

Later I went back out and put the connectors on and it worked for another 1-2 seconds and then died.

I'm thinking there must be a bad/corroded connection somewhere that is either precluding the flow of electrons at some point (which would explain the lack of movement altogether) or making a meager connections (which would explain the dim bulb from the 12V tester used straight on the fore/aft connectors). The problem is, I have no clue as to where I should check for something like this. It seems most likely in the switch, but it's a brand new switch and I don't want to take it apart if I can avoid it.


Is this one of those "electrical gremlins" that I always hear complaints about?

WallyP

One electrical problem that can be very frustrating is when a connection or component will pass full voltage but not full amperage - think a stranded wire with only one strand intact...

You may have burned a wire, or you may have a connector that has gotten hot.

Or, the seat motor may have a thermal breaker inside (the window motors do). This is a tiny thermal circuit breaker that opens if the motor pulls too much current for too long. The little contacts can get burned and/or corroded and cause problems.

I have successfully opened a window motor and cleaned the contacts, and have also failed and had to by-pass the thermal breaker.

glack

Has anyone made those "I love Wally" shirts yet?

This is what I did:

Opened up the motor and found the tiny thermal circuit breaker (made by "Otter" in the UK). I pulled it out and soldered a by-pass then tried the motor with the switch connectors - no luck.

I knew that Wally was right, and I took to figuring out the amperage issue. The soldering job on the back of the switch looked solid for both relevant wires (fore/aft) direction. I pulled the rubber sleeves off of the connectors and re-crimped a new connector onto one of the wires.

I was trying to do everything before opening up the switch as they are a PITA to put back together (at least for me). Alas, I had no luck with the above and took to popping the switch apart. It was hard to tell, but it looked as though one of the springs was stuck under the pivoting contacts. I spent 45 minutes just putting the switch back together and was livid the whole time (cussing, frowning, etc.) that Porsche would not test the switch before it left the factory.

Anyway, it's working now.

Thank you guys for your help.