LeMans71

As the title says I'm trying to bring the fog lamps on my '89 S2 back to life. I've checked the obvious - replaced bulbs, fuse good, etc. I think there is an associated relay, but don't know how to check that. When it comes to most mechanical stuff I consider myself pretty competent, but electrical systems are my nemesis. Any help would be appreciated - a checklist, a "how to troubleshoot 944 electricals" guide, a list of common failure points (switch, relay, etc.) - would all be welcome.

Thanks in advance,
Scott

Wipeout

Relay G11 is the foglight relay. You should have all of the fuses and relays printed on the underside of your central electrical panel lid, but if it's not there, I can send you some high-res photos of mine. Relay failures are unlikely. Not impossible, but not common.

When you turn the headlight switch, then flip the fog light switch, does the switch light up?
If you remove the bulb and use a voltmeter in the socket when the switch is on, what happens? have you had the bumper cover off? Are you sure that the connector from the electrical harness to the foglight housing is fully connected?

LeMans71

Darren, thanks - I was hoping you'd chime in, as you seem to be the lighting guru around here. Your headlight thread was very helpful - the other part of my pending lighting work is putting in a Rennbay headlight harness and some H4s, based on your research. Thought I'd start by getting my fogs working, though. I'll do all those tests and report back.

Wipeout

I think guru is a bit much, but glad I'm able to help. What I'm wondeirng right now is if it's an issue with your switch, your relay, or your wiring.

I'm in the middle of helping some electrical people (folks who can actually wire stuff) figure out what pins are what to wire in a second switch for the euro driving lights, so I have some additional ideas depending on what your checking turns up.

Luis de Prat

Hi Scott, just as a datapoint, if the wiring behind the assemblies gets too bunched up it can cause the foglights to not work at all.

I recently had this problem when they were taken apart and replaced in haste by a shop chasing a headlight problem that turned out to be a cracked headlight harness.

When I took my 951 in for annual inspection the fogs were inoperative. Took the assemblies out, unplugged and reconnected all the wires and they're working again. Good luck with it!

NOTE: Be extra careful and use a quality phillips screwdriver and flashlight to remove the foglight assembly screws, because they are easily rounded out and not available separately from Porsche. I messed one up and had to drill it out. It's a good idea to match them at a hardware store and replace them while you're at it.

LeMans71

Well. . . turned out that the big fix entailed replacing a couple of bad bulbs, and then using Darren's detailed troubleshooting method:

"When you turn the headlight switch, then flip the fog light switch. . ."

Like I said, electrical systems are my nemesis. . .

Thanks for the help guys. Darren, are you working on a way to turn on the fogs without having the headlights on? I'd be really interested in that.

PS - Darren, do you happen to know this car? http://portland.craigslist.org/mlt/cto/1162389289.html
Kinda far away from me, but it looks like it could be a decent candidate for a 944Spec car. . .

Luis de Prat

Unfortunately, this often leads to a dead battery from forgetting to turn the fogs off. Parking lights don't drain it nearly as quick.

Wipeout

Here's the good news...you didn't have to do any extra troubleshooting! I spent ages messing with the bulb in my clock all because I didn't understand when the light in the clock comes on.

I have not messed with turning the fogs on without the headlights on. I am working on wiring in driving lights and probably will use switched 12v (like the radio) for the switch for the driving lights. That way, when the car is off, the lights aren't on, but as soon as the radio would have power, those lights would come on. Here's how TechnoDuck wired his driving lights:



So, in theory, you could splice pin 6 into 12v power on the radio instead of its current setup (connected to the master headlight switch) and have the fogs coming on with the parking lights.

Why would you wire the driving lights (or fog lights) this way? If you wanted them to STAY on when the high beams are on. That being said, driving lights are only supposed to be on with high beams, and fogs are only supposed to be on with parking lights or low beams.

Hope none of that was too confusing! I'm not familiar with that 944 here in Portland... If I hadn't tweaked the frame of my '85 I'd probably have a spec chassis. At least I have lots of good parts if I locate a chassis and decide I want to race.

theedge

Read the post by Randy_J in this thread. And yes, this WILL let you run your battery flat.

https://rennlist.com/forums/944-turb...-together.html