The bulbs in the tach are brand new LED bulbs and they both work fine. This problem was also present BEFORE I replaced the tach bulbs. As stated previously, the turn signals on the four corners of the car all work properly, that is, there is no switching from the left turn signal to the right turn signal on the outside corners. This problem is only seen on the two turn indicators on the tach.

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This post was auto-generated based upon a question asked on our tech article page here:

Have you tried new non LED bulbs?

Check to see if you might have something wired incorrectly.

Pay close attention to the multi connector #85 for corrosion or possible damage, or partial short

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1973_CIS_legend1.jpg

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1973_CIS_Part1.jpg



- Casey

Try a new flasher relay

you could have a bad ground or something connected wrong.

first thing i would do is pull the wire off the left bulb in the tach and remove the led bulb. connect a test light to ground and probe the contact for the bulb with the left turn on. then repeat for the right. if the test light flashes its either the led bulbs or a wiring/ground problem after the bulbs.



use a test light, not a MM.

Ballonmeister, I am unable to decipher what your issues is with the tach turn signal indicators from your thread. Can you provide a more detailed description of the fault.

I think he has one side of turn signals on the tach ghosting when he uses the turn signals.
Ground or polarity issue from the led's is my guess.

Targa80: I apologize for the poor description of the problem. What happens is if I place the turn signal stalk in the down or left turn position, I get a flashing green light in the "left" indicator on the tachometer. After it flashes a few times, it then switches to the "right" indicator on the tach (the turn signal stalk is still in the down or left turn position). When it switches to the right turn tach indicator the light is dimmer. It will sometimes switch back to the left indicator where the green light is brighter again. I do not have both of the tach turn indicators on at the same time. It is either the left or right, switching randomly, with the left (correct for the turn stalk position) brighter than the right. All of the turn signal bulbs on the outside corners of the car work properly. This problem does not happen when the turn stalk is placed in the up or right turn position. In that case, the right green indicator flashes brightly until I cancel the turn stalk indicator. I appreciate all of the comments and I will be working through each of the suggestions to fix this problem (I hope!)

It could have something to do with the 4 pin flasher and the way the grounds are done on this vintage 911.

Instead of have one side of the tach indicator light go to ground, Porsche has the flasher provide ground on each flash. The other contacts on the flasher provides +12 volts.

I have led lights for all my running lights on my 1973, so I had to install an electronic adjustable 3 pin flasher. I just ran a ground for the - side of the tach indicator lights. Works well..

I used to get a an occasional "shadow flash" when I put in LEDs. The left indicator would go on and when off the right indicator would light dimly for a fraction of a second. It was that ground that was causing it.

I feel your pain as I have a very similar issue. I'm using LED bulbs but had the issue with regular bulbs as well. Recently replaced flasher relay.

1978 SC. Most of the time; when I signal left, my tach indicator blinks a strong right and when I signal right, my tach indicator blinks a weak left. Some of the time; right works correctly. Everything is cool from the outside.

The intermittent nature leads me to think ground issue, but I have not been able to pin it down for months.

Any other suggestions from you electrical wizards? Thanks!!

I had previously posted the attached thread on a mod I did to my Flasher relay circuit. It may help you in solving your problem.

http://forums.pelicanparts.com/porsche-911-technical-forum/819548-flasher-hazard-mods-my-80sc.html

Thanks for the advice. First I swapped out the LEDs for the original bulbs; did not help. Then I took your suggestion. My test light fired correctly for both right turns and left turns. So as you say I can now look for a ground issue after the bulbs. That also tells me that neither I or the PO was silly enough to just reverse the bulb locations.

Targa80 seems to have solved this by his mod, but for some reason I am reluctant to use a different flasher and ground things differently

Can I do a targa80 half mod where I keep my correct flasher but add a ground on each bulb?

I'll study the wiring diagram and see what else I can come up with.

You can add the ground to the bulb wiring but I would suggest remove the connection from the C contact wire from the flasher assembly. The mod I did can be reversed in less than 5 minutes. Since I only added a ground wire to the flasher relay connector C terminal and the three prong relay I used has no C terminal. If I ever have the crazy craving to buy a more costly OEM 4 post flasher relay it is easily unmodified.

Thank you Pat.

Do you think it would work to just unplug the connection at C and then add a length of brown wire (with appropriate connectors) to the blue/white and then connect to a known good ground contact in the front trunk? C would then be left without a connection.

I'll give it a try tomorrow and see what it fixes and what it messes up.

Looking at the 81SC schematics both BL/WT wires from the tach directional lights are tied together to the C terminal on the flasher relay connector. There is no way to disconnect the BL/WH wire run without doing damage and or permanently modifying the wiring or connector. Again, the simplest mod is what I have done and it is completely reversible. I tested my circuit with a three pronged flasher I bought at Autozone. Since I knew that my Hella flasher relay failed and was supplying stray voltage onto the terminal C causing the two tach directional lights to light continuously. I decided to open the flasher and unsoldered the terminal C prong and remove it from the flasher. This removed the stray voltage from the tach directional light circuit. When I tested the flasher relay in the modified circuit it worked and the two tach directional lights operated normally.

http://forums.pelicanparts.com/uploa...1423970950.jpg
This is the original Flasher relay that had failed and was supplying a stray voltage instead of supplying a ground to terminal C.
http://forums.pelicanparts.com/uploa...1423970983.jpg
This is the relay with the C terminal completely removed. (now it is equivalent to a Three pronged relay with terminals 49,49a and 31).
http://forums.pelicanparts.com/uploa...1423971020.jpg
This is the relay connector with a male spaded ground wire plugged into the C terminal.
http://forums.pelicanparts.com/uploa...1423971062.jpg
This is the modified flasher with the modified flasher relay connector.

So I have returned from a week OCONUS and got to work on the flasher problem tonight. I first replaced both of the front turn signal bulbs (dual filament type) and the problem of the turn indicators on the tach remained. I then removed all of the fuses, buffed them with an emory cloth and reinstalled - the problem still remained. I then replaced the flasher relay located behind the fuel gauge and the turn signal indicators on the tach now work properly! The relay was very hard to remove - it just didn't seem to want to come out. Mine was a four pin type and I replaced it with a new four pin type. Thanx to all for helping on this - much appreciated.

Now, here's another question for you. Is it normal for the oil pressure gauge (second gauge from the left side) to come on (both needles moving and lamp lit) when you turn on the ignition switch just before starting the car? Mine does that and I think maybe Porsche did that so that a driver would immediately see that he had oil pressure as soon as the car was started and before pulling out the headlight switch.

Thanks again Pat; the pics you supplied finally made it into my thick skull. I'll pick up a EP36 flasher relay at AutoZone and give it a try, with a brown ground wire (male spaded) going into terminal C.

I'll let you know how it all turns out.

Harry....what brand/model number flasher relay did you buy that worked? As mentioned before, there are several reports by pelicans that uro and wittron do not work. I bought a nos hella that did not help me either.

Kerry,
From my Pelican order confirmation:

914-618-303-11-M206 $15.00 1 $15.00
Turn Signal/ Hazard Flasher Relay (4 pin) Brand: Wehrle (1972
Porsche 911 T Coupe/Targa)

Just checked my 1978SC. When I just start to turn the key both the red and green lights turn on. The needle moves just a fraction, from just below 0 to 0.

Hope this helps

Pat.....Success! I bought the EP36 relay from AutoZone for $15 and replaced the older Hella. As you showed in your mod, I ran a ground wire from C to a ground spot in the trunk. Now the turn signal indicators both work as they are supposed to.

Thank you for all your help! This really was a simple mod that can be reversed in less than five minutes. At some point I would like to test another 4-prong relay, but for now I'm just glad the indicator lights work properly.

Now on to the next electrical gremlin. I do believe that this car is actually British with Lucas components.