1972 911 - Flasher Unit

[McOtto]

A while back I started experiencing an occasional situation where, when turning left, the left turn signal indicator light on the tach would blink but fade out. Sometimes both left and right signal indicator lights would blink dimly. The front and rear directional lights all worked correctly. Additionally, the brake warning light on the oil gauge correctly and uniquely blinked when the hand brake was engaged. The emergency flasher light also correctly and uniquely blinked when using the emergency flashers. Thinking the problem was a faulty flasher unit, I pulled the unit, which was a Hella TBB3 RWBG 96P 2x21W-12V.

I have since installed three 4-pole replacement flasher units (Porsche Genuine 914 618 303 12, Wehrle 54 201 102 A, and URO 12499). For all of them, the turn signal indicators and all directional lights work correctly and brightly. The emergency flashers and flasher light work correctly as well.

However, when the parking brake is engaged, all three of the aforementioned replacement flasher units cause the brake warning light to flash, but it also flashes both turn signal indicator lights (which means Terminal C of the flasher unit is being energized). That is not correct.

It could be a parking brake/brake warning light circuit grounding issue where resistance is driving up the power draw, thus causing the flasher unit to energize Terminal C. That could be the case since the emergency flasher system is functioning properly, without blinking the directional lights. The other possiblity is the flasher unit and finding one that has a 2x21W + 0 function???

Has anyone experienced and solved this problem? Thank you!

[jaudette3]

We have experimented with a number of electronic flashers since we sell LED Signal Light Bulb kits (currently 20% off). The best 4-pin electronic flasher that we have found is the CEC-EF26. We sell them HERE.



Cheers,
John

[McOtto]

With invaluable and very much appreciated help from ESR Senior member, 304065, problem solved. Closing this thread, the issue was threefold:

1.) Turn Signal/Emergency Flasher Unit Spec: The original, factory installed Hella TBB3 RWBG 96P 2x21W-12V relay unit appears to be the only one that works as Dr. Porsche intended. I installed three other 4-pin units that are reportedly interchangeable with the Hella: Porsche Genuine 914 618 303 12, Wehrle 54 201 102 A, and URO 12499. None of them worked properly.

2.) Flasher Unit Repair: As mentioned in my initial posting, when engaging the hand brake; the brake warning light blinked, so did both directional signal lights on the tach. Only the brake warning light should blink. This problem was corrected by removing the Hella flasher relay unit cover and cleaning the two internal relay contacts (49a and C). Once cleaned and reinstalled, problem solved - only the brake warning light blinked.

3.) Turn Signals: After reinstalling the flasher unit, I checked turn signal function. The right turn signal and right directional signal light on the tach worked fine. However, the left directional signal light would initially flash, then both left and right would blink (an indication of a turn signal bulb problem). I checked the front and rear turn signals. The front-left was lighting up, but appeared to be a little dimmer than the front-right. Cleaned the socket, changed the bulb, and the left directional signal light on the tach started working properly.

The Hella TBB3 relay units are no longer manufactured and good used ones are hard to come by. Spokeworks LLC offers a great, inexpensive alternative.

https://www.spokeworksled.com/911-led-solutions

Spokeworks sells a modified Novita EP26 relay which bridges relay pin C to the grounding pin. I tried it and it works. However, that solution disables the warning feature where the left and right directional indicator lights flash when a turn signal bulb is out. It also requires moving the left directional indicator light to the right side of the tach and vice versa because relay pin C becomes a ground instead of a pilot. This would be very easy if it did not require removing the steering wheel and column clam shell to pull the tach and get access to the directional indicator lights. But overall it is a straightforward, sure-fire option to an original Hella relay.

[thelews]

Spokeworks sells a modified Novita EP26 relay which bridges relay pin C to the grounding pin. I tried it and it works. However, that solution disables the warning feature where the left and right directional indicator lights flash when a turn signal bulb is out. It also requires moving the left directional indicator light to the right side of the tach and vice versa because relay pin C becomes a ground instead of a pilot. This would be very easy if it did not require removing the steering wheel and column clam shell to pull the tach and get access to the directional indicator lights. But overall it is a straightforward, sure-fire option to an original Hella relay.

My flasher happens to be a Novita and I did just what was described jumped C and 31 (ground). It behaves now exactly as you describe. I'll see if the Zims flasher works before switching wires at the tach.