68S signal light relay

[rs-vic]

Hi Gang,

I am sorting out the electrical on a 68S, I got the turn signals and hazard figured out thanks to fellow Pelicanites and 2 hours of reviewing the wiring diagram and testing each wire. BTW, the square relay on the right for the hazard flash does not work. There is a good link that explains it. I am thinking of doing the VW Bus relay there.

Need advice - "Blinker" (Hazard) Control Unit early 901

What I can't figure out is what is the purpose of the signal light relay, the left one in the picture below. Everything works fine, I just don't know why it is needed.



This is what I have found. First click of the light switch gives power to 85 on the relay which energizes it. Second click 85 goes away and 56b (low beam) gets power. This comes from the fuse box but has nowhere to go because the relay is no longer energized. See diagram below. BTW, what do the little square boxes at the end of the wires mean?




When the light switch is on the second click and switch for high beam (on the stalk) is activated, 56a (high beam) gets power and so does 30/56 at the relay. High beam flash sends power to 30/56 regardless of position of the light switch. I removed the ground to the relay and everything still works the same so what is the purpose? Is it just so you can't accidentally turn on the high beams when the light switch is in the first click?

[304065]

Greetings, I am the author of the original "Kluge" as the 912 BBS ingrates refer to it. . .

The short answer is that our cars were not originally designed with a hazard system- it was added on later (or not at all, for certain euro-market cars). The hazard system is actually independent of the turn signals and would interfere with the signal circuit during operation. So the control light relay REMOVES control over the bulbs from the turn signal circuit and flasher and powers up the Hazard flasher.

(for the LWB cars both circuits were integrated)

Check this out, it will answer your questions in detail.
SWB Relays Analyzed

Ach, I see you are asking about the "relay for light signal"-- this is detailed in the linked thread.


ALso the white squares are reference markers- they allow you to trace the wire to its other end. Follow it all the way with your finger you will see a white box on the other end. Some of the cars have tape on the wire for the same thing, to aid diagnosis.

[rs-vic]

Thanks for the link. Today I found out that with the light switch in position one, running lights, the headlight flash is over the low beams not high beams. The reason I know is yesterday the right H1 bulb for the high beam burnt out, but when I checked the light flash today I had two lights.

On another note, this is the second time the right side high beam bulb has burnt out in short time. It is a NOS headlight and the wiring harness in the car was replaced with one from Y&Z. I am wondering if maybe the ground is not good enough.

[rs-vic]

Here is the info from the link from our moderator. This is exactly what I wanted to know! Thanks! If I had an owner's manual I might have known this. It still doesn't make sense as the relay does not help the power load on the stalk switch anyway. Crazy Germans.



Gray Relay Logic

From owners manual p. 20
Light switch pushed in (lights off)- pull stalk switch- headlamps flash high beam

Light switch in position 1- parking lights- headlights flash LOW beam
Light switch in position 2- headlamps on- stalk switch normal, low beams on, stalk switch pushed or pulled, flash HIGH beam
Light switch in position 2- headlamps on- stalk switch forward, high beams on.

The place to start analyzing this circuit is the gray relay. The gray relay has two outputs-- 56a, a white wire, for the high beam, and 56b, a yellow wire, for the low beams. The gray relay's ONLY function is to implement the logic described above. It doesn't switch power in lieu of the headlamp switch, despite what the FWM claims.

With the headlamp switch in the OFF position, the relay's wiper is making contact between the high-beam output (56a) and the input (30/56). 30/56 is connected to 56a on the stalk switch. When the switch is pulled to the rear, power flows from 30 (unswitched feed from battery) to 56a, up to the relay and out to the high beams.

Looking at the diagram (and the blown-up version that's actually useful, contained in the hazard description) it appears as though the switch makes contact between 56a and 56-- but the trouble is that 56 is only powered up with the headlamp switch in position 2. I'll check the "as-built" contacts on my spare switch and correct this.

With the headlamp switch in Position 1, the parking lights are on, and the parking lamp indicator in the speedometer is illuminated. Also in this circuit (green/white wire) is power to the gray relay's coil, which pulls the wiper in so that terminal 56b and 30/56 are in continuity. This time, when the switch is pulled, the LOW beams illuminate, per the factory logic above.

With the switch in Position 2, the parking light indicator goes out, and the relay coil de-engergizes, bringing the wiper back to resting position, with continuity between 56a and 30/56. This time, when the switch is pulled, the high beams illuminate, again per the factory logic.

Why go to all this trouble? Well, probably DIN rules.

The FWM claims that the relay is used to bypass high current around the stalk switch, this is just incorrect. It says
The headlamp flasher signal is released by means of the combination switch on the steering post. The flasher relay switch is situated under the left floorboard.

The purpose of the flasher relay switch is to reduce the current load of the headlamps, i. e. , routing
the high current flow through heavy contacts in the flasher relay rather than through the switch on
the steering post.
Looking at the diagram, since the input 30/56 to the gray relay comes from the stalk switch, then all power comes through the stalk switch for both high and low beam.