Badfish89

I am a new 928 owner, brand new to Rennlist AND this is the first time I have ever used a forum...it only took me 20 minutes to find that little button that says "thread tools" to figure out how to post this question! Anyway...
I have an 89 S4 5-spd that seems to have a few gremlins in the headlights. First of all they started just popping up and turning on all by themselves. While at work the other day this equated to a dead battery. After some minor troubleshooting this is what I have found. The relay is clean inside and out and is clicking whenever I turn the headlight switch on off or try to use the hi beams. When the headlight stalk (on the column) is (FWD) in the hi beam position the headlights will go up, turn on and then go down once the switch is off... except no hi-beams and no blue hi beam indicator in the dash. If the stalk is in the low beam(AFT) positon the headlights will go up and turn on. But when the headlight switch is turned off the lights go off but the pods jump a little and just stay up. If I take the stalk and push it FWD to the hi beam posit the headlights will retract. The hi beams do work, but only if you hold the stalk in the pass/flash position. So my question is (finally)...Which component is the guilty one? Could it be the relay or is it the column stalks/switches. As a side note, the turn signal stalk is defective in the fact that it does not automatically shut off the turn signals after the steering wheel returns to center. But I don't think this has anything to do with the current problem. Any advice or troubleshooting techniques are appreciated. Thanks and sorry for the wordiness.

bigmac

Welcome to the shark tank. Mac

Alan

Well the indicator behaviour is unrelated. The high/low beam difference is interesting it should not normally effect the raising & lowering of the pods in any way. The 'pull to flash' high beam feature doe not use the relay and is direct drive vis a the column switch...

The most likely culprit is the headlight relay - though the main light switch is also a possibility.

Behaviour should be:

Pods go up with light switch in Position 2 (of 0,1,2) only with accesories/ignition on (no other dependencies)

Pods go down only with light switch in Position 0 and accesories/ignition on.

Unless there are other related symptoms I'd say its 80% likely its the relay - there are several things that all point to the relay

Alan

Badfish89

Alan:

Thanks for the reply. The relay is kind of what I thought too. I opened it up and it doesn't look like there is anything wrong with it, but then again I have no idea on how to troubleshoot it. I guess I'll just order the relay and see if it fixes it. Thanks.
BJ

Mrmerlin

IIRC we had this same problem and the turn signal switch was the culprit it had a melted connection and thus it wasnt fully contacting one of its tabs inside the switch. A new switch cured this.
Check the relay first for clean contacts both the blade conections that plug into the CE panel and the relay connections inside. If you check all of the fuses and find any that have corrosion on them its a good chance the blower box needs a reseal. www.928gt.com for a fuse chart

Alan

The failure you note would not be entirely in the contacts - possibly just the ho/lo relay switch is stuck in low mode (relay terminals 56, 56a & 56b).. however it seems the control portion probably has issues (the pod issues...) and that could also account for the hi/lo issue too.

You could check the high lo switch input to the relay - relay socket terminal 86 with ignition on and light switch in 2 - it should be 12v+ with high beam only (stalk forward).

Alan

Madmarek

Alan have you ever put together a write up on all the different combinations that the headlight circuit should see? I have been going through some of the latest headlight threads with your comments and find them very helpful.

IE:-relay socket terminal 86 with ignition on and light switch in 2 - it should be 12v+ with high beam only (stalk forward).

Also is there a writeup anywhere on how to bench test he headlight combination relay. I have messed around with mine with some success but don't understand how the device with the X lead works.

My problem is that with the igntion on, switch moved to 2 , no high or low beams. If I pull the relay and jump contacts the lights come on with the jumper. (Can't remember which now).

The headlights do go up and down properly.

Alan

Well I do actually have such a thing - but its part of a huge project I have currently on the back burner due to my day job getting in the way

I have a 400+ page document I'm trying to get finished about the 928 electrical system. Its quite comprehensive but still needs lots of finalization. Due to the huge amount of work into this I can't justify just distributing it for free so it will be for sale sometime - its actually close but I've not been able to spend any time on it for the last few months. I actually wanted to get feedback on it but only a few of those who have seen parts of it have ever provided any feedback (to them thanks!) so I also have to proof-read the whole thing myself. This is not only more work - its hard to see your own errors or shortcomings - only elapsed time allows a little more perspective.... & so far its been 3 years....

For your specific problem check that terminal 86M on the socket goes to 12v+ when the lights are in 2 and ignition is on. If it doesn't I'd say you have a main light switch or wiring problem. If you get neither high or low beams then the combination (column stalk) switch is not implicated.

Test terminal 86 on the relay socket in high beam with lights in 2 and ignition on
as above should be 12v+ if not check your xbus on relay socket X terminal should be 12v+ with accessory and ignition position.

One other thought - does your headlight motor get very hot when the lights are on...

Alan

Madmarek

I think the book will be very popular. I have a 78 corvette pace car and when ever a book/guide like this comes out initially people jump on it.

I will try what you said. You refer to position 3? Is that headlights on with the highbeam switch actuated?

Madmarek

One thing I forgot. Could this be an ignition switch problem?
Surfing around the posts some threads alluded to headlight problems related to the ignition switch.

Alan

Whoops corrected - I meant "2"

Its possible its the ignition switch hence the X & relay test

Alan

Madmarek

The 86M does not have voltage in the scenario above. I will start tracing back to the light switch.
Is the ignition switch in this circuit?

The key used to feel "funny" but now it seems to feel ok is why I am asking.

You should publish your work in a partial format like everyone else does. Make it a volume I and II etc.
or Basic and advanced. See how the public responds.

Thanks for all your help.

Alan

Test the X connection to the relay as noted... The ignition switch X (accessory) output drives the control for the light relay and feeds the headlight part of the light switch...

Could be the light switch - could be the ignition switch or the wiring on that circuit. the X output is also used to drive the pods up & down - so the ignition switch seems like it probably works....

You say - do it - "like everyone else does.." I'm not sure anyone else does anything in any way similar...

However The first part of my document (chapter 1 if you like) "Porsche 928 Electrics - Wiring Diagram Primer" will be in Jim Morehouse's next CD set and is available for free as a sampler - but it won't help you much on lighting issues (just on reading the factory wiring diagram schematics).

Alan

Madmarek

Will try tonight. Buti I think I had 12v at the X with ignition on. Will check.

I genuinely hope the document works out for you. I have seen works like this in the past but they are so specialized that only the people really into "topic" find them. Some old Harley books were put together in a way that several topics were discussed and then a volume II or advanced version came out.

Madmarek

Ok checked everthing tonight.
with the ignition ON and Lights on 2 the pods go up and stay up all is normal.
Lights are not on, highbeams do not work either.

86M, 56a, 30bM, 30M have + 12v

all the rest read zero to ground.