1986 911 Diode for Running Lights, help!

[356power]

My 1986 carrera has a dead diode just beyond the headlight switch and the part has been discontinued! Wehrle 911 617 108 00. Grey wire with red stripe. Running Lights.
Can anyone help find one of these? I have tried all the online resources and dealer, no dice. Thanks.

[Jim727]

I'd call these guys: SF Bay Area Porsche New & Used Parts || EASY - European Auto Salvage Yard

Welcome to the board!

[john walker's workshop]

i just remove it and attach the wires. haven't seen any issues doing it that way. i often wondered why it was there. why is it there?

[Canada Kev]

I know this might be a bit obvious, but with it being a diode, there is probably another (potential) source of electricity somewhere else in the circuit on the other side of it and they don't want it to back feed through. I have absolutely no idea of what it might be, though. What does it show on the electrical diagram?

[McLovin]

It's a "mystery part" for which no one has seemed to come up with an answer.

It's odd because (1) it is ONLY on the '86 model year, which appears to otherwise have no difference in the wiring circuit from the other years, and (2) it is only one one side of the parking light circuit (pass side?).

[Canada Kev]

Maybe the reason it's NLA is that it doesn't serve an actual purpose?

[356power]

Correct, when it goes out it only effects the Passenger side running lights. Weird. I had Jim and John at Easy climbing through all their parts and they found two of them for me and another guy that I am helping with the same issue. Thanks Guys.

[Rot 911]

It does nothing. Took mine out 6 years ago and everything continues to work as normal.

[ischmitz]

Hm, the only diode I see is in the charging system of the 84' Carrera. And that is to prevent run-on when you turn off the ignition. Without it the alternator D+ can feed current back into Terminal 15 when you turn the igniton off.

Is there another one on a 86 that is not shown in the WSM (that I have)

Ingo

[Eagledriver]

I had one side of my running lights go out on my 86 Carrera years ago. I had no idea that there was a diode. I just jumpered the two sides together and got all the lights working that way.

-Andy

[34Carrera]

Originally Posted by syzygy

I know this might be a bit obvious, but with it being a diode, there is probably another (potential) source of electricity somewhere else in the circuit on the other side of it and they don't want it to back feed through. I have absolutely no idea of what it might be, though. What does it show on the electrical diagram?

My understanding is that diodes are commonly used to prevent the voltage spikes that happen when a relay is de-energized (the current needs to go somewhere) from arcing across one's switch contacts. One can have 300V+ spikes from a 12V relay which can potentially wear out one's switch contacts over time.

http://www.aeroelectric.com/articles/spikecatcher.pdf

[ischmitz]

An inductive load will produce a spike when a circuit is interrupted. That is how a Kettering ignition works. The coil induces a voltage spike to counteract the breakdown of the field.

This is why relays (or inductive loads in general) that are driven off a semiconductor have a diode across the coil to supress this spike. Modern automotive relays have these diodes built in and there is no need to add external diodes.

[dshepp806]

there to reduce contact "chatter"....

Doyle

[surfrider]

Does anyone know the specs for this crazy diode? I just found out I need one. Thought I could find replacement at radio shack.
Thanks....
Sara

[dshepp806]

Anyone know the spec on PIV (peak inverse voltage) for these diodes.....? (aside from it's current rating)

Doyle

[86 911 Targa]

Originally Posted by 356power

My 1986 carrera has a dead diode just beyond the headlight switch and the part has been discontinued! Wehrle 911 617 108 00. Grey wire with red stripe. Running Lights.
Can anyone help find one of these? I have tried all the online resources and dealer, no dice. Thanks.

Had the very same issue many years ago on our '86.

Our passenger side parking lights went out.

My factory circuit diagram showed the "usual suspect",
however finding it was an interesting search.

Using a multimeter, I found the diode to be open.

I bought an equivalent diode, and all has been well since then.

Just go to your local electronics store, buy the diode, and solder it
to the pc board.

I put two in parallel for redundency.

Good luck,

Gerry

[surfrider]

Hi Guys,
Thanks for your quick responses....
I did order part #91161710601. The staff at PorscheOEM in San Francisco
said I could interchange the parts.
What do you think?
Thanks again...
Sara

[ChiefPlumber]

News Update:

I just learned that Classic-Service (Porsche factory parts for the old guys) is bringing back the diode. You will again be able to order this "unique" PITA part from the dealers. I still have not heard from ANYONE why they put the diode in the circuit, but I am sure it has to do with voltage flowing in the wrong direction and illuminating the bulbs.

[83_Silberpfeil]

I found this same part: 911.617.108.00 in my 1983 SC while removing the aftermarket (Hofco III) alarm system. It was attached to the wiring just behind the passenger side frunk hood strut. The wiring connects into the hood open/close sensor that triggers the frunk light. I don't know why it is there, but I removed it.

Looked up the part number and came across this thread. A few posts above indicate it is for 1986 Carreras only, not before. But this is an interesting case (exception?) in an 83 SC.

I hope my front passenger side marker will still work w/out this diode.