Turn Signal/High Beam Indicator Lights

[MichaelN]

1981 SC. Intermittently when I actuate the turn signal lever, either left or right, the corresponding indicator light located on the speedo face will begin blinking appropriately, and then all of a sudden both indicator lights will begin blinking simultaneously (like emergency flashers), but at a slightly dimmed brightness. Sometimes it will correct itself, sometimes not. Jiggling the turn signal stalk seems to have no effect. This happens randomly but frequently. Also I noticed that the high beam indicator light does not light at all (Unless it is now too dim to see in daylight. I'll have to check again tonight). All the light functions - turn signals, high beams, low beams - work normally. It is only the indicator lights that malfunction.

I was going to begin troubleshooting at the turn signal stalk until I confirmed that all the light functions were unaffected; it's only the indicator lights that display a problem. So now I'm wondering if I should pull the speedo and begin there?

It's a small problem but it bugs me, so I thought I would check to see if anyone has had the same problem.

[spoke]

A secondary relay in your flasher relay has lost efficiency and is not pulling in. You need a new flasher relay. You can go with EP26 for LED-compatibility (still drives bulbs) or get an OEM flasher replacement.

The older 911's (up to '85) and all 914's used the tach turnsignal indicators to alert the driver that an exterior turnsignal bulb has burned out. They did this by wiring the indicators in series then the center connection was taken back to the flasher on pin C2/K2/K.

A secondary relay in the flasher would connect C2/K2/K to 12V if both bulbs were ok or open if one was burned out. When C2/K2/K is open, both indicators would flash (less brightly) together.

However this secondary relay loses its efficiency over time and stops pulling in. Sometimes folks would see one or two correct flashes then both would flash.

[MichaelN]

What a thorough, clear explanation. I’m grateful.

[2.7RS]

Where is this secondary relay located?

[targa80]

The following first post will provide some insight to the tach flasher circuit and it’s failure modes. The second post shows how I modified the tack indicator light circuit to use a FLAP cheap 3 prong flasher instead of the more expensive 4 prong flasher. I did this mod in 2015 and have had no issues since with the circuit.


https://forums.pelicanparts.com/porsche-911-technical-forum/819548-flasher-hazard-mods-my-80sc.html?highlight=Flasher


https://forums.pelicanparts.com/porsche-911-technical-forum/850904-911-turn-signal-indicator-issue.html?highlight=Turn+signals

[targa80]

The following first post will provide some insight to the tach flasher circuit and it’s failure modes. The second post shows how I modified the tack indicator light circuit to use a FLAP cheap 3 prong flasher instead of the more expensive 4 prong flasher. I did this mod in 2015 and have had no issues since with the circuit.


https://forums.pelicanparts.com/porsche-911-technical-forum/819548-flasher-hazard-mods-my-80sc.html?highlight=Flasher


https://forums.pelicanparts.com/porsche-911-technical-forum/850904-911-turn-signal-indicator-issue.html?highlight=Turn+signals

[spoke]

Originally Posted by 2.7RS

Where is this secondary relay located?

The secondary coil is inside the OEM flasher. It has really heavy wires of much fewer turns than the main relay coil which has much thinner wires and many more turns.

One thing about EP26 should anyone decide to use it. The C2 pin on EP26 is open inside the flasher relay. I resell EP26 where I short out C2 internally to ground. This does cause the turnsignal indicators to flash opposite. Simple fix is to pop out the tach and remove both indicator bulb assemblies and simply put them in the opposite holes. The 914 is wired the same way.