Service Light and Sunroof

Hi all,

I have two issues in my 1989 760 GLE that are currently only rated as
minor annoyances but I'm still hoping to resolve them.

1. The "Service" light. This came on and I was able to reset it by
removing the rubber cap on the glass of the instrument panel and
depressing the plunger concealed therein. This has only solved the
problem partially: while pressing the button DOES reset the light, the
light still comes on again every few days. Once reset it stays off for
a few days and then returns. Otherwise it is functioning normally,
illuminating when I start the car and extinguishing automatically
after 2 minutes of running. Ideas? Secondary reset?

2. The "centre position" on my sunroof seems to have disappeared. Used
to be if the unroof was open (slid back) and you pushed the button to
close it the thing would close and then, if you wanted to have it pop
up in the back, you'd have to press the switch again. Similarly if the
back was propped up and you wanted to open it fully you'd have to
first shut it then press again to have it slide open. Now it just goes
smoothly from one position to the next and it's a bit of a guessing
game as to when it's actually shut. Is this electronic (some sensor)
or mechanical (some pin) or something else entirely?

Thanks for any suggestions,
Blurp

 

There are limit switches built into the motor and gearbox housing which cut
off the motor when the "roof closed" condition is satisfied.

 

There an ingenious mechanism of gear driven cams, microswitches and a
solenoid inside the sunroof motor that makes it stop in the center
position. When the sunroof switch sticks, the solenoid is continually
engaged, and burns out. Then the motor doesn't stop in the center
position. I've actually disassembled the motor and rewound the solenoid
to fix this problem.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

That seems worth a try. Will the solenoid reasonably evident once I
get the sunroof motor open? If I can do no good I'd like to at least
do no harm since the motor DOES work otherwise.

blurp

 

It's pretty obvious. There will probably be some light scorch marks
visible on the outside of the white plastic housing where it's
installed. You'll need a soldering iron, and make notes of which wire
goes where.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Well I got it all open but the problem wasn't evident. Inside the
white plastic part of the motor assembly I found a stacked pair of
microswitches (each to kill the motor at either extreme end of travel)
and a rod-and-coil-type electromagnetic plunger which appears to move
to engage BOTH switches at the closed position. No scorch marks and
all wiring connected, including the very fine ends of the copper coil.
The lower microswitch does not work but the odds of getting a
replacement seem impossible.

Thanks anyway, I guess I'll just live with it until I get a line on a
cheap replacement for the whole thing (or get a manual crank
assembly).

Thanks again,
blurp

 

Those microswitches are pretty standard. You should be able to match it
at an electronic supply store.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)