Where's my headlamp flasher changeover relay?
 

Hi , I have just changed my indicator switch from a newer (SC?) indicator switch to an early switch that better suits the car - yeah!!! Everything works as it used to and the switch feels fine.

The only thing is that my main beam flash doesn't work but there again it never has.

I wanted to investigate why that would be. I followed through the electrical diagram and established that the most likely reason for it not working would be the headlight flasher changeover relay.

From my understanding the changeover relay takes an output from the Indicator/Light switch and makes the main beam.

Can someone kindly point out where the really should live so that I can check that it is installed/faulty.

My car is a 1971 911T Targa

Thanks in advance.

Neil

it should be behind the oil level/fuel gauge remove them to see it


Lorne M

I have just edited my original question as I was probably using terminology loosely. I want to know where the headlamp flasher changeover relay is. It may well be where Lorne identified it to be but my thought was that behind the oil/fuel gauge was the location of the Indicator flasher relay.

Sorry for any confusion.

Cheers, Neil

I don't know whether earlier Porsches had factory headlight relays. The SC's certainly did not. All headlight currents run through the indicator-headlight-flasher switch on the left side of the steering wheel. Lots of people install after market headlight relays for better lighting and to save the indicator-headlight-flasher switch.

Porwolf, I may very well be mistaken but I have looked at 2 different wiring diagram versions for a 1971 car and there is what is called a Headlamp flasher changeover relay that is in the path from the indicator/headlamp switch to the fuse for the Main beams.

My take is that this unit may be there to switch off dipped beam if main beam is flashed. I thought that it may be missing or faulty. The main beam works when I switch to main beam. The dipped beam works when I switch to dipped. But the flash does not work when I pull on the stalk.

This is probably a red herring as the Main and Dipped beam work from the Headlight switch function on the Stalk. Therefore it is presumably the switch or the wiring....

Cheers, Neil

OK then your car has that "switch over relay". But from your description I would strongly suspect that the switch at the steering wheel stalk is the culprit. Maybe taking it out and checking with a continuity tester on all the possible contact functions could solve the problem. I the case of the SC switches, they can be repaired.

I just looked up an early electrical diagram:

http://www.pelicanparts.com/911/911_parts/Electrical/911_electrical_1965.jpg

and it seems that you have a different directional-headlight switch than the later cars like the SC's. That earlier switch seems to also include washer controls which in an SC is controlled by a different switch. And there is a "Relay for light signal" (No.43). I am stumped because of the unfamiliar territory. Maybe your problem is the "Relay for light signal". That should be a relatively easy problem once you can find it.

I hope somebody familiar with your 1971 Porsche can chime in.

Thanks for looking into it Porwolf. I agree with you, after thinking about it and looking at a number of diagrams, there should be a feed from the headlight switch when I 'flash' the main-beam which doesn't happen but there is only one main beam output from the switch.

It must not be being switched by the replacement switch and it probably just needs cleaning.

I do have H1 headlights and the JWest relay kit installed and the headlights work well other than this particular function. My thought that the problem lay elsewhere was due to the fact that the previous headlight/indicator switch also didn't enable main-beam flash.

I will, once I get to the bottom it, let you know what the issue is.

Cheers, Neil

SWB Relays Analyzed

See above thread for how the early cars work
Once you break out of the factory diagrams you're a test pilot

304065 that was really helpful. I have got to the bottom of my problem.

I had an (SC?) indicator/headlight switch installed in my 1971 car
All functions worked except the headlight flash
I presumed it was a problem with wiring elsewhere because:
I changed to the correct switch from an early car; and
All functions worked except for the headlight flash

This is why I started looking through wiring diagrams.

Anyway, when I started looking at the SC? switch I removed it was clear that it was different electrically from the ones in my diagrams. I also noted that most instances of 'flash failure' seemed to be due to contacts needing cleaning or bending slightly.

Sure enough when I partially removed the correct switch I was able to manipulate the contacts and I had the flash function restored.

It goes to show that when you get 2 consistent faults you shouldn't necessarily rule out 2 different issues.

Anyway, it works and I am happy!

Thanks for people's input.

Regards, Neil