hacker-pschorr

928.615.127.00
I have an 81 and 87 in the garage, I don't see anywhere this relay is used on them to borrow one, or is there one hidden in some other location than the relay board?

The headlights in my 79 are suddenly working in reverse.

At first they were randomly doing what they wanted when I turned them off / on. I swapped in a different headlight motor relay and now they go up when they should be down, and down then why should be up. I put the original relay back in, no change.

The power supply relay also feels warm....doubt that's normal.

This is after installing the euro fog / running lights.
The fog / parking / turn signal lights are connected to the stock wiring (and still work fine). I have not connected the running lights yet, so right now everything is stock. Post install I tested all the lights, no issues. A few hours later I was leaving a friends house and this started to happen. Thankfully it was only dusk so the fogs were enough to make the 2 mile trip home.


EDIT -

During my various testing of relays and checking things over, I noticed the relay in question getting warm. Per my temp gun it's 7 degrees warmer than the other relays....except for the blue window motor relay next to it which is 5 degrees warmer than the rest.

Guess today's drive has a sunset curfew.......pulled the possible bad relay just to be safe. I don't like things getting warm in the relay panel.

James Bailey

Unique to 78-79 only, not available new for many years. Never heard of a substitute but know the later one does not work. But you knew that

hacker-pschorr

That's what I figured.... Want to test one to be sure that's the problem.

hacker-pschorr

Houston, we found the problem!!

hacker-pschorr

For future reference in case anyone is playing along at home....


It looks like the diode on pin "A" got a bit toasty, reparable by someone with better soldering skills than me.

Since this relay is NLA and cannot (safely) be bypassed with a simple jumper wire, this should be added to the "toolbox" of any 78/79. Thankfully Mark Anderson had one on hand.

I'm not sure how common this failure is, I'm sure it didn't help how many times in a short span I turned the lights off / on testing my "new" lights.



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LT Texan

I hate to ask, but what is the purpose of having the 2 diodes in series with the electromagnetic coil?

hacker-pschorr

It all sort of started here:
https://rennlist.com/forums/928-foru...-and-79-a.html

The relay was bad, however, as I suspected that was not the end of this issue. Thankfully whatever is causing this did not immediately blow the new relay.

Long story short, my fog, driving, and front turn lights are disconnected.
Every relay has been removed except for these, which have all been bench tested:

III - Headlight Motor
IV - Headlight Power Supply
XIII - High Beam Power
XIV - High / Low Headlight
XVI - Headlight Safety

Here is what they do......

This is with the headlight switch in the OFF position and I'm manually cranking them down:







Here is what happens when I cycle the headlights on then off:

Mrmerlin

it appears that the arm that attaches to the motor has been placed in the wrong position or has slipped on the shaft.

So remove the arm then cycle the lights. This should park the motor in the correct position.

ALSO before you do any more please post the wire colors that you have connected to the 4 pin connector at the motor
NOTE the connector has numbers on it so please note the wire color to the pin

hacker-pschorr

This was the first thing I checked when the headlights went wonky, the nut was tight (and still was). Upon inspection.....yup, the piece is worn and not grabbing the shaft like it should. Tom at 928 International said he's sold a few of these so must not be terribly uncommon.

Talk about horrible timing. If this had happened at any other time during my ownership of this car, I would have concentrated on the mechanical side of things, not electrical. However, when they "broke" within hours of my re-wiring all my front lights and poking around the fuse panel.....my mind was stuck on some electrical issue. Finding that blown diode in the relay was the icing on the cake!!!

Here's the really ironic part to all this. Considering I rewired the fuel injection / ignition in my 81, worked with Z to modify my relay panel in that car, added God knows how many different electrical gizmo's in that car......this was the first time I've ever had to touch the relay panel in the 79, after 11 years of ownership.
Needles to say, I'm now intimately familiar with the 79 electronics and wiring diagrams

Not sure why you are asking for this? I never touched that connector.

Mrmerlin

please ,
just pull out the end of the motor harness,
and tell me what the the wire colors are going to 1 2 3 4

hacker-pschorr

Sorry, thought this was part of the diagnostic of my lights, not info you needed.

1 - White w/ Black
2 - Brown w/ Red
3 - Green w/ Yellow
4 - Red w/ Black



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Alan

It gives you 2 independent ways to turn the relay on that don't interact with each other in any other way.

Alan

Mrmerlin

Thanks for the picture,
just for the heck of it go to the WD and see if the colors match.

Alan, if the two wires in the center of the connector are switched vs the WD, what will/ wont happen?
The two wires on my 85 Euro appear to be switched as this connector and the lights work as advertised

Alan

All but the red/black control the stop position.

The WDs aren't clear about the mapping of colors to 1-4 (they are labelled functionally). Erik as long as the red/black stays in the same place you can try swapping the other 3 connectors as Stan proposes - or try all 6 ways...

Alan

hacker-pschorr

Electrically everything is working fine now, so I'm not touching any more wires.....

Mechanically.....that's another story.