Doug_B_928

Hey guys. Unfortunately I'm not here very often these days because I'm too busy doing the (seemingly endless) metal work on my 914 restoration project. I'm looking forward to spending more time here (if I ever get the 914 done).

I have noticed an issue on the 928 ('79') that is bugging me. This is a new phenomenon for this car. When I turn on/raise the headlights, they are in high beam mode (even though the lever on the stalk is at the low beam setting). Fiddling with the hi-lo lever on the stalk does nothing. So what I have to do is raise and lower the headlights several times with the hi-lo lever in different positions (i.e., hi or lo) and eventually (usually after 5 or 6 times) the lights will be on low. After that, the lights switch from hi to low as normal (i.e., the lever on the stalk works perfectly). Anyone seen this before and know what the problem might be?

Alan

Likely the low & high beam wires are intermittently shorting together in/under the headlight buckets where they flex as the pods rotate up.... I'd check that wiring. Wheel off - remove splash shield & wheel liner for access.

Alan

Doug_B_928

Doug_B_928

Mrmerlin

the wires will be damaged where the metal clamp holds them next to the body,
you will have to cut open the sheathing to investigate look at the harness see what happens to it when the lights go up does the wire get tight,
its best to give it some more slack

davek9

Why not disconnect the wires (both ends) and Ohm them out before cutting up anything, is there no access?
Just asking

Dave K

Doug_B_928

I finally had a chance to get the 928 out of winter storage and spend a little time today trying to diagnose the hi-lo beam issues. Recall the issue is that when I turn on the headlights, they are automatically in hi beam even though the switch is set to low. Rather than cutting the pristine sheathing around the wires under the headlight buckets looking for a short, I tried to test for continuity to see if a short would show that way.

There are two relays for headlights in my car (MY 79). They are different from one another in their markings. The headlights seem to work from both of them. According to the 79 wiring diagram, if I read it correctly, there should be a headlight dimmer relay (XIV) and fuse 2 should also link to this. But my owners manual shows that relay is a bridge for the starter and fuse 2 is ‘unused’ (even though there is a fuse in the #2 position). So I’m not sure which is correct. If there is a relay for the dimmer then switching that out would be the easiest thing to try. Below is a snip from the wiring diagram showing the dimmer relay:




Anyone know which is correct, my original owner's manual or this diagram?

I’m calling the relays ‘left’ and ‘right’ based on their location on the panel.

I’m attaching pics of the relays so you can see the terminal markings.

Left Relay:



Right Relay:




Here are the results of the continuity test (recall that the headlights have 3 wires: white, yellow, ground):

With hi-low switch in low position:

Right Relay with Right headlight:

Continuity between White wire and 87, 31, & T
Continuity between Yellow wire and none
Continuity between Ground wire and 87, 31, & T

Left Relay with Right headlight:

Continuity between White wire and 31 & 53M
Continuity between Yellow wire and none
Continuity between Ground wire and 31 & 53M

Right Relay with Left headlight:

Continuity between White wire and 87, 31, & T
Continuity between Yellow wire and none
Continuity between Ground wire and 87, 31, & T

Left Relay with Left headlight:

Continuity between White wire and 31 & 53M
Continuity between Yellow wire and none
Continuity between Ground wire and31 & 53M

With hi-low switch in hi position: identical results to above.

So, it seems likely to me that the yellow wire is the low beam and it’s as though the switch has cut power to those terminals. But, if it’s a problem with the switch, I don’t understand why retracting and turning on the headlights over and over eventually gets the low beams to work….Thoughts?

Doug_B_928

Bump.... Anyone know if the 79 NA has a headlight dimmer relay (which would mean the owner's manual is incorrect)?

Doug_B_928

UPDATE: Being unsure if Relay XIV is for the 'Dimmer' or starter, I stopped by both the local VW and Porsche dealers to see if they happened to have the correct relay. Interestingly, even PET at the dealer showed XIV as a starter relay. They are NLA but I ordered one from the aftermarket via the dealer to see if that was the problem. I just switched it out and the low beams are back. So, it turns out that XIV in the NA '79 is, indeed, a dimmer switch relay.