924Board.org

Stampedetrail · Joined: 29 May 2005 Posts: 274 Location: Fairbanks, Alaska

Hi! So the wife says "we need a project car," and I says "Hey there's a Porsche in the paper dirt cheap!" Well, one year and thousands of man hours later, yes indeed, there's a theoretically functional Porsche in the driveway. Just finished replacing the cold start valve, and other than that, I've done brakes, belts, oil leaks, exhaust manifold gaskets, and lots and lots of wiring. Pulled the starter more times than I care to recall. I'll upload some pics as soon as I find some webspace to do so, but in the meantime, I have a small favor to ask:
Could someone please upload a pic of the wires hooked up to their functioning pop-up headlight motor? The PO had disconnected them & run a hot wire from a switch in the console directly to the motor, so if you want the headlights up, you have to time it just right and that's annoying. I pulled the motor & found a bad diode (which must have been the original source of the problem); replaced the diode but I now have 4 loose wires & I dont want to try all the combinations. I would greatly appreciate a pic or just a summary of the order of the wires from left to right. A brief description of the system would help a lot too. Thanks you all.

BTW it's red, but I'd like to get it back to original black.[/img]

Khal

Peter_in_AU · Joined: 29 Jul 2001 Posts: 2745 Location: Sydney, Australia

Hey, if you know what a diode is and you know if a diode is bad or not then how come you're not giving lessons in how to read Porsche current-flow diagrams?

Ok, it's dark and cold outside and mine's a `79 but according to the diagram in Haynes p246 the wiring is "easy".

First up, you don't have 4 wires going into a `77 headlight motor, you have 3:

A green wire connected to one of the diodes that then loops over to the second diode (connectors 58 and 58b). The other end of this green wire goes to the fuse box pin A2 and works its way to the light switch

A red wire that connects terminal 30 on the relay on the motor to ignition-switched power (circuit 15).

And a brown wire that goes from terminal 31/87a on the relay on the motor to an earth point.

Pull out the soldering iron and the multimeter.

BTW, your wife wouldn't happen to have a sister would she?
_________________
1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you

Stampedetrail · Joined: 29 May 2005 Posts: 274 Location: Fairbanks, Alaska

Stampedetrail · Joined: 29 May 2005 Posts: 274 Location: Fairbanks, Alaska

OK did some testing. Red & white wires are flat under all conditions, i.e. off, run / Headlights off / park / lights on. Brown is grounded. I can rewire, but could you let me know or point me in the direction of pin A2 on the fuse box? I think I can connect everything else up. Thanks for your help.

Peter_in_AU · Joined: 29 Jul 2001 Posts: 2745 Location: Sydney, Australia

like I said, you're looking for a green wire (no trace colour).

"A2" is part of the "A" plug on the fuse/relay panel. It is the ivory coloured plug at the end (not the white one near the middle).

If you start at the fuse/relay panel and follow the wiring harness connected to the "A" plug through the fire wall and into the engine bay you should eventually find a green wire just hanging around looking suspicious.

If it was me I'd check the area around the headlight motor. The PO most likely just cut the wire off and tucked it away somewhere close.
_________________
1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you

Stampedetrail · Joined: 29 May 2005 Posts: 274 Location: Fairbanks, Alaska

Peter_in_AU · Joined: 29 Jul 2001 Posts: 2745 Location: Sydney, Australia

hmmm, I missed the part about a white wire. If the white wire is factory then it indicates you have a late 77/78 car or at least wiring loom. If that's the case then the white wire is the relay earth.

OK, pull out the relay attached to the headlight motor turn it upside-down and find pin "31". The connector this goes into is connected to ground so crank up the multimeter, select continuity and stick one probe into relay connector "31". Probe the four wiring connectors and when you get a hit that's where your brown (76 - 77.5) or white (77.5 - 78 ) goes. As you seem to have both a brown and a white wire then use whichever one is connected to ground or most convenient if they both are.

Find the connector that relay pin "30" goes into. This is your power. The wiring connector that "30" is attached to is where the red wire (76 - 77.5) or blue/red wire (77.5 - 78 ) goes.

The remaining two wiring connectors are connected to the green wire that goes to the switch. The green switch wire is attached to BOTH of these connections.

When you find the green wire it should have 12v on it when the light switch is on and the ignition is on and nothing when off. If after all this the motor still doesn't work and you're sure that your connections are correct then you may need to pull the motor and check the connections to the base-plate that controls the switch-off when the lights are up and the return when the switch is off.

To find out what model-year your car is click the "924 Registry" link at the top of the page and click the VIN Decode link.
_________________
1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you

Stampedetrail · Joined: 29 May 2005 Posts: 274 Location: Fairbanks, Alaska

1977
924
California, USA
Non-catalyst

Nothing wrong with the motor, just the connection between the car and the mechanic is a little loose. OK I'll try it that way-- from the wiring diagram I have, it looks like, as you've stated, the green wire that goes to 58 also loops around to 58b, main power goes into 30, and ground is 31. As I said though, all the wires are flat where they attach to the motor, except of course brown, which is indeed grounded. be back with results.
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1977.5 924 "Martini" head / New Old Stock rebuild
1985.5 944 Why? Because I can.

Stampedetrail · Joined: 29 May 2005 Posts: 274 Location: Fairbanks, Alaska

Just to follow up, none of the original wires are functional except brown ground. Possible fault is the mass of melted wiring at the headlight switch, it's a complete miracle that the lights-- any lights, worked at all! So I rewired that, which was a real dirty job & I'm still not completely satisfied, but in the meanwhile I wired pin 58 to pin 58 of the starter motor, hooked pin 30 of the starter motor up to accessories on the ignition switch, grounded the ground 31, and the only issue left is the second ground, 58b. I have a console switch Im using to connect that ground when its time for them to go down. They pop right up when the headlight switch is thrown when the ignition is on, just fine. So I donno, I could trouble shoot it some more but I'm relatively happy with it now.
Thanks for your help & advice.
_________________
1977.5 924 "Martini" head / New Old Stock rebuild
1985.5 944 Why? Because I can.