Mrmerlin

The headlight switch should have its own light in it that comes when the key is in the run position its not uncommon to have the bulb fail. The rest of the switches should all have their lights come on when the headlight switch is installed i hope a new ignition switch cures this, Though since the harness cooked i would bet that there are other wires that need to be fixed

Jim bailey - 928 International

I got the phone call the car started right up with the new electric ignition switch....all is working except the headlights are not going up ! So much is improved with the switch change.

Mrmerlin

great news thanks Jim B

gf261

First and foremost, thanks to EVERYONE for all of your help. Per Jim's suggestion, I raised the headlights manually, turned the switch, and they're just a shining. For the uninitiated, (Read ME before today, thanks again Jim.) the headlight motor has a limit switch which is triggered when the lights are all the way up or down. Nothing complex there. The other portion of the equation is that once up, or starting to go down, this same switch triggers the relay that activates the headlights. Evidently I have a bad headlight motor, but I do have lights once again.
Mrmerlin, admittedly, I was nervous that I had missed something in the CE panel during the repair, but I put nearly 100 miles on her this evening and she hasn't missed a lick. All switches illuminate now as they should.
Thanks again Jim, Alan, Mrmerlin, and ZEUS+.

gf261

By the way Jim, you should throw in either a Bible, or the alcoholic beverage of choice when someone orders an ignition switch. That way, regardless of whether one chooses to invoke the deity or take a stiff drink to get through installing the top screw on the switch, they're covered!

Alan

Actually although I always thought it worked this way a few months ago I realized it is actually slightly different. The limit switches sort of work as you describe for the headlight motor drive which is via the headlight relay. The 2 switches break contact when they get to the park position - one for each direction.

The headlight turn-on actually works based on the motor drive signal rather than the up-limit switch itself. As long as the relay is trying to run the motor in the up direction the headlights are disabled from turning on... only when the relay stops trying to drive the motor up do the headlights go on.

This is almost the same thing as directly monitoring the limit switch - but can cause some slight differences in behaviour.

If the motor drive relay fails the lights will come on because it isn't trying to drive the motor up.

Also if the up limit switch is disconnected the lights can still come on...

I believe Porsche did this for ~3 reasons that seem to make sense:

1) Either the motor or the headlights are active but never both at the same time - even in failure modes (avoids extra loading.. both stock headlights are about the same power as the motor).

2) If the headlight motor stalls while still driving up (due to end stops & limit switch misalignment) the lights will never come on - so you probably won't leave them this way... in this mode the motor will eventually burn out - it is not designed to sit stalled or even to operate continuously.

3) If the headlight motor is faulty - it and the limit switches can be disconnected and the headlights when wound into the up position manually can still operate normaly.

Alan

gf261

Alan, as usual, you are a plethora of knowledge. Understanding how something works goes a LONG way toward making it work again after it's broken. I always feel much better when I post a problem and see that you or Jim(among several very knowledgeable others here) have left a reply. Wally Plumley is often my go-to guy on these matters, but he's out of town until next week, so once again, many thanks.
Alan, all joking aside, I have something that I'd like to send to you as a token of my appreciation for all your help since I've been on Rennlist. It's not much, but I'm going to send one to Jim as well. If you could PM me a mailing address, I'll get it out to you some time next week. It ain't much, but I guarantee you that it's something that no one else in Arizona or California (on Jim's behalf) has.
Take care...I'm going for a drive in my fully functioning 928!!!
Garrett

gf261

And please include a shirt size!!!