Need Help with Light and Turn Signal Issues

[KerryM]

Sorting out a new to me 1978 Targa project car. I'm not sure if I have one issue or three:

1) With keys in my pocket.... the headlights (only) turn on if I turn the left blinker on; with turn signal lever in "neutral" headlights do not turn on by pulling on the headlight switch.

2) With car running and headlights off.... outside turn signals work fine; green directional arrow on tach blinks dim left for right turns and bright right for left turns.

3) With car running and headlights on.... right outside turn signals work fine, but left outside signals do not blink (stay on); green directional arrow on tack does not light for left turns and blinks very very dim right for right turns.

I replaced the turn signal / hazard relay with one from our host, and it made no impact. Searching this forum revealed that some of you did not think this Wehrle relay works very well. I need the four prong one not the newer three prong one.

I have also examined the turn signal stalk. Other than readjusting the high beam / low beam contacts, everything looked fine although it is impossible to see the actual contacts for the turn signals; all wires looked to be secure and not touching each other.

Also checked/replaced all bulbs with correct wattage ones. Hazard lights work fine.

What do you think my next steps should be? Thanks!!

[Paulporsche]

Check the grounds and all other connections. Poor grounding from corrosion etc cause a lot of electrical issues.

I'm not sure, but is there a L/R orientation on the back of the dash indicator?

[timmy2]

Clean grounds to the signal lamps front and back.
Indicator wiring on back of gauge may be reversed.

Headlight on when turn signal activated with key off is normal for European parking.

[rockreid]

check inside rear light housings for possible corrosion and ground issues. Check to see if there is any old sealant floating around inside causing a problem. My old 73.5 rear housings were causing all sorts of weird erratic lighting conditions like you are describing. Cleaning them up inside seemed to solve them.

[KerryM]

I knew the parking lights went on when turning on turn signals when the car was off, but I had not heard that the left blinker turning on the headlights was a "feature".

[targa80]

Problem (1) This may be a feature on a ROW car as noted by timmy2, but my 80SC only turns on the left front and rear parking lights when turn stalk is engaged for the left turn position with car not running. The same occurs if the right side flasher is selected. The streets are narrow in some places in Europe so the car may be parked half on the road and this provides a warning to oncoming traffic at night.

Problem (2) This can have two problems, one is the bulbs are reversed (easy fix just swap wire and bulb sockets. Second problem bulb dim in one direction and rapid flashing in other direction. This is now a part of problem 3.

Problem 3 You mentioned that you installed a three prong flasher instead of a four prong and it did not fix the problem. Check to make sure that the bulbs and contacts are good. If you do a search you will find a thread where I did a very easy mod to use the three prong flasher in my 80SC. It seems that in~1985 Porsche modified the flasher circuit to eliminate the terminal (C) from the flasher. The four prong flasher has terminal (C) connected to both return contacts of the turn indicator lights in the tech. The flasher normally provides a path thru internal circuitry from terminal (C) to terminal (31), terminal (31) goes to chassis ground. The Porsche 85 mod eliminated the terminal (C) wires and ran them straight to chassis ground. In my own case the four prong flasher internal circuit failed. Instead of providing a ground at terminal (C) it provided close to battery voltage. My fix was to use the three prong flasher and added a jumper wire from the flasher connector terminal (C) to chassis ground in the trunk. This fix is easily removed when a replacement four prong flasher is available.

In my opinion the four prong flasher is over designed and causes a multitude of failures modes and Porsche finally realized it and went with the mod to the three prong flasher in~1985.

[KerryM]

targa80...thanks for the advice. I did not write clearly regarding the turn signal / flasher relay. I replaced the 4 prong (original?) Hella relay with a 4 prong Wehrle relay from our Host and it made no difference. A forum search revealed several people that said that our Host's relays do not work for them, and that a more expensive Porsche brand is required.

There are several ebay sellers claiming their generic looking relays are OEM and the same as a Porsche dealership sells. These cost about $50 vs $16 for the Wehrle from Pelican My local dealership said the relays (914-618-303-11) are NLA.

Has anyone else recently had an issue replacing this relay, and what specific brand relay did you find that worked??

[gtrp]

KerryM,

Did you ever solve this issue?


81' 911sc - Weekend Project Car
09 GTR - Race Car

[gtrp]

Bumped!


81' Widebody SC

[zl0ca]

I'll try too.

[dicklague]

The 4 pin flasher can easil;y be converted to a 3 pin. Do a search there was an article here about it.

The key issue is the ground on the Tach indicator lights. You have to ground one side rather than having it go through the flashe. The 4 pin flasher has both the ground side and + side run by the relay which is really a strange and wasteful design.

I use a 3 pin that is adjustable and electronic so I can use LED bulbs in the directionals for more light. Works like a charm.