front turn signals out '73 911

[chauser]

73 911
Both front turn signals have been erratic (worked then stopped)
-thought they were loose in housing, refitted & cleaned contacts.

Now they are both not working, rears are working as are all 4 flashers, so I don't think it's the relay.

Don't think it's a lost ground either as front running lights come on as do headlights.
Fuse is OK.

Suggestions?

Likely unrelated, but I have also had issues with fuel gauge not reading accurately even with replacement sender unit.

Charles

[brianlay]

Now they are both not working, rears are working as are all 4 flashers, so I don't think it's the relay.

Are you sure all 4 corners are flashing because they are the same lights? 4-way flashers simply turn on L and R directionals at the same time.

Yes, the flasher relay is fine.

[chauser]

You are correct, all 4 flashers are not working, my bad.

Just checked and right front turn signal is working, left is not.

With key off and left signal switch on, both running light and turn signal light are on.
With key on, and left signal switch on, neither lights are on.

[E Sully]

One of the interesting functions mentioned in the '73 owners manual is that with the ignition off if the turn signal lever is pushed down the left side parking lights will come on, and pushed up the right side parking lights come on.
In this thread are some diagrams and functions for a 1971.
1973 should be similar, but there may be a few small differences.
http://forums.pelicanparts.com/porsche-911-technical-forum/1154724-71-turn-signal-function.html

[brianlay]

The parking light function controlled by the directional stalk is on most of our cars. It's sometimes confusing to some folks but remember it's different lamps from the directional signals, just uses the same stalk.

The front directional signal have fuses, but the rears do not. I would check the fuse, especially to see if it might be corroded on the ends and not making good contact.

A 12V test light will confirm if there is voltage getting to, and through, the fuse. I'd be surprised if there is not voltage since (pre-fuse) it's the same feed to the rear lamp.

More likely voltage is not getting from the fuse to the front lamp.

Do some checking and report the results.

[Showdown]

Even though you say it’s not the grounds, with these damn cars it’s always the grounds.

Check them twice and then try grounding them directly to the battery with a jumper wire.

Don’t trust Porsche’s grounds… ever.

[chauser]

OK, the puzzle continues.
Here are results of testing blinkers with with and without key on:



blinkers worked correctly so should not be wires crossed.

Thoughts?

[brianlay]

I’m assuming blinkers and turn signals refer to the same lights?

1- Which hazard lights (4 corners) work? Hazards should work the same with ignition key on or off

2- With key off and headlight switch pulled to the first position which corners are lit?

With key off and directional switch moved left or right, which corners are lit? Those are the same lights as test 2, only on left or right. Those are NOT the directional lights

With key on, which directional lights work (both front and rear)?

Fast flashing indicates just one directional bulb is working.

[brianlay]

I think your front left directional bulb is not working

[chauser]

Originally Posted by brianlay

I’m assuming blinkers and turn signals refer to the same lights?

1- Which hazard lights (4 corners) work? Hazards should work the same with ignition key on or off


All 4 corners work, however the DS FRONT, it’s the ‘running light’ not the small ‘turn signal ‘ light that is blinking.

On the PS FRONT, it is the small ‘turn signal’ light that blinks.

2- With key off and headlight switch pulled to the first position which corners are lit?
All 4 corners are lit.
On front, both running and turn signal lights are on (both DS & PS)

With key off and directional switch moved left or right, which corners are lit? Those are the same lights as test 2, only on left or right. Those are NOT the directional lights

Key off, left signal: both running and turn signal on as is rear.
Key off, right signal: same as for left.

With key on, which directional lights work (both front and rear)?
Key on, left signal: front running light, rear, normal blink speed
Key on, right signal: front turn signal bulb, rear both flashing fast.

Fast flashing indicates just one directional bulb is working.

Maybe problem is right- should BOTH front bulbs blink, I thought just, small bulb?

[chauser]

Update
I switched the 2 front ‘running light’ bulbs ( larger dual-filament), and now everything works as it should.

I was mistakenly naming these larger bulbs as ‘running lights, but they are the turn signal lights, the smaller are side marker lights.

I’m at a loss as to why switching the 2 bulbs resolved the issue though, but do think the problem arose due to something on right not left?

Gremlins

[brianlay]

The dual filament bulb use one for directional and the other for running light.

so now there is no problem?

[chauser]

Correct, switching the 2 dual-filament bulbs -> both turn signals working
Not sure what to make of it.

[spoke]

Originally Posted by chauser

Update
I switched the 2 front ‘running light’ bulbs ( larger dual-filament), and now everything works as it should.

I was mistakenly naming these larger bulbs as ‘running lights, but they are the turn signal lights, the smaller are side marker lights.

I’m at a loss as to why switching the 2 bulbs resolved the issue though, but do think the problem arose due to something on right not left?

Gremlins

Many of the electrical issues with older vehicles are caused by oxidation and dirt on electrical connections. Take this bulb below from the brake socket on my '86 930. The bulb was so stuck in the socket that I worried I'd break the bulb removing it. Needless to say, the socket was in just as bad shape as the bulb.

I replaced the bulb with LEDs and had a devil of a time cleaning the socket enough that the LEDs would light properly.

You may want to take some time and clean the sockets and bulb bases.

[chauser]

I believe my problem may have been due to the bulb inserted 180* off, so wrong contacts being made in socket.
Even though alignment pins on bulb are asymmetrical I may have had it in incorrectly- dope!

[chauser]

Originally Posted by spoke

Many of the electrical issues with older vehicles are caused by oxidation and dirt on electrical connections. Take this bulb below from the brake socket on my '86 930. The bulb was so stuck in the socket that I worried I'd break the bulb removing it. Needless to say, the socket was in just as bad shape as the bulb.

I replaced the bulb with LEDs and had a devil of a time cleaning the socket enough that the LEDs would light properly.

Did LEDs work ok, I read they may not work with the flasher relay?

[spoke]

Originally Posted by chauser

Did LEDs work ok, I read they may not work with the flasher relay?

The flasher relay did hyperflash and I replaced it with EP36 which is LED-compatible and can drive incandeescents too.