Diode Help

[Uwon]

'86 Carrera wiring.
Don't know much about diodes..... New one costs $56.00.
I pulled out the diode (#91161710600) that sits between the headlight switch and The hazard flasher module /right parking light split and tested it with my multimeter.
Set the dial to diode mode-starting reading .640v not connected to anything. Reads zero when the probes touch each other.
Checked circuit one way and it reads .636v and when reversed it reads .629v.
Guess that the diode is pooched. Do you agree?
Any idea what the readings should be as I have a big diode from an old HID headlight unit that might work. Just tested it and it reads .440 one way and .640 when I reverse the poles.
Thanks in advance.
Cheers,
Johan

[T77911S]

if it is the one i am thinking of, you really dont need it. i think the one you are messing with is the one that blocks power from goiing to the license plate light when you you the "turn signal parking lights". you know,the ones that come on either left or right depending wich way the signal is turned. i dotn use that feature on my 930 so i just removed the diode.

try check just on the ohms setting. one way will be a low resistance theother way a very high resistance.

i just checked a large diode here at work with the didode feature on the MM. .466v one way, an open the other.
checking with resistance, 1,4M one way, an open the other.

[JJ 911SC]

Normally a diode check on the Ohm meter should be almost short one way and open the other way.

[LM3929]

I have a diode if you are looking for one

lorne m.

[86 911 Targa]

Originally Posted by Uwon

'86 Carrera wiring.
Don't know much about diodes..... New one costs $56.00.
I pulled out the diode (#91161710600) that sits between the headlight switch and The hazard flasher module /right parking light split and tested it with my multimeter.
Set the dial to diode mode-starting reading .640v not connected to anything. Reads zero when the probes touch each other.
Checked circuit one way and it reads .636v and when reversed it reads .629v.
Guess that the diode is pooched. Do you agree?
Any idea what the readings should be as I have a big diode from an old HID headlight unit that might work. Just tested it and it reads .440 one way and .640 when I reverse the poles.
Thanks in advance.
Cheers,
Johan

The diode you refer to blocks voltage to your pass side parking lights.

And yes, you do need it.


^^^^^
Here are pics of the diode holder.




^^^^^
And the diode location.

As for the replacement diode, if needed, take the diode holder to any electronic shop who will sell you one for a buck.

Just unsolder the old diode, and solder in the new one.

Good luck,

Gerry

pm me as needed.

[Uwon]

Thanks to all four for the quick and informative responses, pics and diagram. I took the cue from Gerry's scientific suggestion and tried the diode from my trashed HID headlights. Worked!
And Lorne, many thanks for you kind offer.
Gotta love this forum-four responses inside an hour.
Cheers,
Johan

[T77911S]

you dont need it.

look at the turn signal switch. there are 2 sets of L/R outputs. one set is used for the flasher circuit for when you are turning.
the other circuit is used when the car and the lights are off and it is parked and you want to turn on the left or righ side turn lights as markers. thye dont flash, they just stay on. that is on the same circuit from the light switch that turns the turn lights on with the lights. the right side also feeds power to the license plate light so the diode is there to block power to the license plate light when you turn the right side parking marker lights on. thats all.
look st the 1.0 GR wire on the turn switch. it goes back to the ignition switch and ONLY has power when the ignition is off.

i left mine off. i dont use that feature. most people dont even know you can.

[86 911 Targa]

Originally Posted by T77911S

you dont need it.

look at the turn signal switch. there are 2 sets of L/R outputs. one set is used for the flasher circuit for when you are turning.
the other circuit is used when the car and the lights are off and it is parked and you want to turn on the left or righ side turn lights as markers. thye dont flash, they just stay on. that is on the same circuit from the light switch that turns the turn lights on with the lights. the right side also feeds power to the license plate light so the diode is there to block power to the license plate light when you turn the right side parking marker lights on. thats all.
look st the 1.0 GR wire on the turn switch. it goes back to the ignition switch and ONLY has power when the ignition is off.

i left mine off. i dont use that feature. most people dont even know you can.

For our '86, when this diode fails (open), the pass side parking lights stay on.

I just disconnected the diode & the pass lights came on.

Gerry

[T77911S]

Originally Posted by 86 911 Targa

For our '86, when this diode fails (open), the pass side parking lights stay on.

I just disconnected the diode & the pass lights came on.

Gerry

i dont see how unless something is wired wrong in your car.
there is another reason to just remove it. (when it is removed connect the 2 wires back together without the diode).

porsche removed the diode in 87 and moved the license plate(LPL) to the left turn lights at the light sw. they added a module that may or may not have anything to do with the park light feature/ LPL. the drawing calls it a control unit only M062(?).
(my drawings are not that clear).

gerry, if you do have something wired wrong and removing the diode turns on the lights then when the diode is in place there is something loading the circuit down that prevents the lights from coming on. this could either cause a drain on the battery or maybe a fire.

with the key off, the lights off and the turn signal centered, you should not have any power on either of the 2 connectors that go tot the diode.

[86 911 Targa]

Originally Posted by T77911S

i dont see how unless something is wired wrong in your car.
there is another reason to just remove it. (when it is removed connect the 2 wires back together without the diode).

porsche removed the diode in 87 and moved the license plate(LPL) to the left turn lights at the light sw. they added a module that may or may not have anything to do with the park light feature/ LPL. the drawing calls it a control unit only M062(?).
(my drawings are not that clear).

gerry, if you do have something wired wrong and removing the diode turns on the lights then when the diode is in place there is something loading the circuit down that prevents the lights from coming on. this could either cause a drain on the battery or maybe a fire.

with the key off, the lights off and the turn signal centered, you should not have any power on either of the 2 connectors that go tot the diode.

I chased this issue down a long time ago & found an open diode in diode holder.

As advised by a dealer mechanic I replaced the diode, & all has been well since.

There are no wiring issues on the car, and nothing is wired incorrectly.

I think that there may be a bulletin from Porsche on this issue.

Best,

Gerry

[Uwon]

Originally Posted by 86 911 Targa

For our '86, when this diode fails (open), the pass side parking lights stay on.

I just disconnected the diode & the pass lights came on.

Gerry

Gerry,
Interesting. On my '86 harness, my passenger side parking lights did not work because the diode stayed open. That was the original reason for this thread. Hmm, I wonder what other little quirks will now rise to the surface as I finish off the electricals on the RST.

T77911S
I hate that left parking light feature-got caught twice over the last 19 years with accidentally not cancelling the turn signal while parking overnight at a hotel. Embarrassing to say the least.
Dead battery!
Cheers,
Johan

[T77911S]

you can disable the feature. pull the 1.0 GR off "P" on the ingition switch.

its only there to keep the LP light from coming on when you turn on the parking light on the right side. (in the 86).

[spyerx]

I've an 89 and my parking light feature seems to not be working. I'm familiar with the function from other German and Porsche cars.

Any thoughts on where to start for troubleshooting?

Also this diode mentioned, it's not clear to me from the pictures where it is located?

Thanks

[86 911 Targa]

Originally Posted by spyerx

I've an 89 and my parking light feature seems to not be working. I'm familiar with the function from other German and Porsche cars.

Any thoughts on where to start for troubleshooting?

Also this diode mentioned, it's not clear to me from the pictures where it is located?

Thanks

I don't think your M/Y 89 has this diode.

Good luck,

Gerry

[heimtun]

I came upon this thread while searching for threads about this diode.
I have a 1980 SC and I think someone took out the diode on my car and just plugged the two wires together. What type of odd things will this cause? How critical is this diode?

[86 911 Targa]

Originally Posted by heimtun

I came upon this thread while searching for threads about this diode.
I have a 1980 SC and I think someone took out the diode on my car and just plugged the two wires together. What type of odd things will this cause? How critical is this diode?

I'm not sure the SC M/Y had a diode.

Maybe someone else will chime in with a service manual.

Good luck,

Gerry

[Uwon]

Originally Posted by 86 911 Targa

I'm not sure the SC M/Y had a diode.

Maybe someone else will chime in with a service manual.

Good luck,

Gerry

You can get the electrical diagram here:
Pelican Parts - Porsche 911 Parts Listings & Diagrams
I found the '78 diagram most helpful as it is in color and more or less matches my '86 harness. In that diagram the diode is referred to as a "resistor" identified as item N6 in position #23 on the scale at the bottom of the page. A couple of sample pages...







N6 is apparently the location of the diode to allow current flow in only one
direction to the hazard lamp.
It's all very overwhelming so I took the advise from a fellow Pelican electrical guru, Dennis, and color printed the entire file and then taped it all together. Lots of time staring and the light bulb finally came on.

Hope this helps.
Johan

[timmy2]

The current flow diagram is like a waterfall, current flow from the pump (Battery) goes up across the top and then branches out and around and finally down to the bottom (Ground) and then gets pumped back up again.

[T77911S]

i dont know if N6 is a diode or resistor. i would have to see it. i dotn know why they would call it a resistor if it is a diode since they called the other diode in there a diode.

N6 is there for the light on the emergency flasher. it looks like when the head lights (HL) are turned on it turns on the light for the EM lights. BUT, when you turn on the EM lights the path from the light sw is broken and the EM light on the sw is now connected to the flasher so it flashes.
N6 may be there just to reduce current to the light.

on the 78 the LP light is wired directly to the light switch so no need for a diode in the circuit.
i guess they tried to save on wire by feeding the LP light off one off the left parking/turn light.

[Uwon]

[QUOTE=T77911S;8679364]i dont know if N6 is a diode or resistor. i would have to see it. i dotn know why they would call it a resistor if it is a diode since they called the other diode in there a diode./QUOTE]

My diode is per post#5 above- same number and same location. The "resistor" reference is likely an error in translation. Haven't we seen that before!!!
Johan