SWB turn signal help

[shbop]

I'm trying to help a friend with his 68' 911. Neither the turn signal or running light work on the right rear. All connections have been cleaned. The brake light and reverse light work fine. A power probe will illuminate both non-working lights. The left side turn signal works fine, but when you switch to the right, both indicators come on, on the dash, and the cadence increases two fold. I'm hoping this is the giveaway hint for some of you more experienced members. Any help greatly appreciated.

[ossiblue]

Jon,

Double check the following:

The fuses for that circuit. Don't assume the circuit is good by looking.
The bulb is, in fact, the correct wattage. Replace with a new one just to be sure.
The bulb is seated properly in the socket. Don't assume just because it's secure that it's in the correct way--especially two filament bulbs.
The contacts inside the bulb socket are clean.
That the front indicator light comes on, is the proper bulb, secure, and has clean contacts/grounds.
All ground wires are connected and clean. Your symptoms are classic poor ground symptoms.

[Porsche_monkey]

This is a symptom of low wattage bulbs.

[304065]

Jon,

I've been through the flasher circuit a few times and even reverse-engineered a replacement for the NLA hazard flasher using modern FLAPS parts.

A power probe will illiuminate both non-working lights. What does that mean? Does that mean you remove the bulb and it lights, or that you apply +12v from some power terminal in the car with a jumper wire to the "49R" terminal on the bulb holder and the lamp illuminates? If ship's power makes the lamp illuminate you can rule out the ground.


The bulbs get power one of two ways: EITHER the turn signal flasher OR the warning signal flasher. A relay, called the warning signal relay, controls which flasher sends power to the bulbs.

The system is set up so that when you operate the warning signal switch, you ground the warning signal flasher, which sends power to BOTH left and right circuits, and you simultaneously ground the warning signal relay, which energizes it and disables the power to the turn signal flasher. Ordinarily the turn signal flasher gets its power from the 87a or "normally closed" contact (according to DIN 72552). When the warning signal relay is grounded, however, the wiper closes, OPENING the 87a contact.

Are you with me so far?

Now, if when you pull the warning signal switch the bulbs on the right side flash, that means there's nothing wrong with the wires to the bulbs, but that it's the wires from the turn signal flasher relay to the bulbs. Start at the socket, which is under the cowling next to the fuse box (right where water drips through a rotten trunk seal). You should have contiunity from terminal 49a (the output) to the right-hand bulb when the turn signal switch is in the "right" position and "left" in the left position.

The other alternative is that someone has installed an incorrect flasher from a later car which will fit but is just wrong, wrong, wrong. A correct flasher for an SWB has three terminals, 49, 49a and C. 49 is the "input" or power from terminal 87a of the warning signal relay as I mentioned. 49a is the output to the bulbs. C is the pilot lamp output in the tach, also a voltage, but with its own internal relay wired parallel with the main relay. This way, the warning lamp blinks faster if there's a blown main bulb, because all the voltage drives the relay for the C terminal.

If someone has installed a Porsche flasher from a later car, the terminals will be 31 (ground), 49, 49a and KBL, which is the pilot lamp. The 31 additional ground was added because the old three-prong flasher had to get its ground from the load, i.e. four filaments and then ground. That's a long distance with a lot of potential for oxidation.

So what does the flasher look like?

Now, as far as the running light, the inner bulbs are two-filament bulbs with TWO bumps on the bottom of the socket. Check to be sure the correct bulbs are installed.

The "cadence" increasing is caused by not enough load in the circuit-all the power is going to the "c" circuit relay and both tach lights are illuminating because the voltage from "C" is higher than what's present on the other side of the bulbs in the gauge. That suggests that the wrong bulb is installed, you aren't getting a load. The fact that the running light is out suggests an incorrect bulb is installed.

Ever notice how weird it is when you look at the wiring diagram and the "L" tach lamp is tied to the RIGHT side turn signal bulbs and the "R" tach lamp is tied into the LEFT side bulbs? Wouldn't that cause the wrong indicator to light? continued later. . .

[shbop]

Ah, Too good John. The power probe illuminated the problem circuits which simply indicated, to me, that the bulbs and grounds were ok at the rear right hand side. I'm going over to my friends' house tomorrow, armed with lots of new info.
On another note-
The 6A wouldn't fit under the seat. I even made 1/4" spacers for the seat tracks. Only in exasperation did I finally cut through the original floor insulation. That gave me at another 1/4", but still not enough.
Thanks as always!

[shbop]

Update. Research lead me to an old post with valuable contributions by John C. from 2002 There was a referral to the 912 site which gave me a part number for a new t. sig flasher (EL 13). I found one locally and installed it in my friends 68'. Things changed. Both left and right t. sig now have the same (normal) cadence. The right rear still does not work, but the dash indicator problem disappeared. They no longer flash together when the right side is activated. I had previously stated that all his connections were clean. This was not the case. #1 fuse was giving us intermittent problems and inspection showed that the whole assembly needs to be cleaned. Hopefully a thorough cleaning will give us a small advantage. Also discovered that the emergency flasher is not working. Small progress but no solution, yet.

[wprater]

I’m having a similar issue, looks like a custom harness was made for my 66 since there was already a 3-prong relay installed. It’s been labeled as 18, 19, 20.

My condition is the indicator lights remain on and turn signals do not function.

An EL 13 relay allows the turn indicators to function in and out of the car, but the lights in the tach stay permanently activated. Any ideas of what would cause that. I tried the EN 36 style and that didn’t allow any function of the turn indicators using the stalk.

Attached pics of my old relay (broken?) and wires going into it.

[Mr. Merk]

Originally Posted by wprater

I’m having a similar issue, looks like a custom harness was made for my 66 since there was already a 3-prong relay installed. It’s been labeled as 18, 19, 20.

My condition is the indicator lights remain on and turn signals do not function.

An EL 13 relay allows the turn indicators to function in and out of the car, but the lights in the tach stay permanently activated.

I've had a mess of problems with mine that varied. Changing the relay would make them work temporarily. We finally repaired the reverse lamp switch on the transmission, replaced the inline fuse (not the one on the fuse block,) replaced the relay under the pedals with the VW bus relay and added a fresh relay as you've shown.

Need advice - "Blinker" (Hazard) Control Unit early 901

I've had the EL13 crap out on me again recently, causing the dash lights to stay on as you described and the opposite signal to function (left instead of right and vice versa.) Luckily they are readily available at all parts stores. I whipped in to local O'Reillys and swapped it out. They seem to not be of great quality and any disturbance will cause a failure. In this case I used an impact nearby.

[wprater]

Thanks for that other thread. I've read up on it but still not sure why the two tach indictor lights will always stay lit up.

My hazards operate fine -- blink all four corners and the indicators in the tach.
The external turn signals operate fine with a new EL 13 installed.
The issue with the tach indicators staying lit is what Im trying to solve now.

both tach lights are illuminating because the voltage from "C" is higher than what's present on the other side of the bulbs in the gauge. That suggests that the wrong bulb is installed, you aren't getting a load. The fact that the running light is out suggests an incorrect bulb is installed.

Suggests that I have installed the wrong bulbs, but the running lights are operating.

[wprater]

Another update. A shop in San Antonio had a go at this while working on other items. They kept the original hazard flasher relay and used a flasher relay in the trunk labeled 3P 12V LED Flasher and grounded to the chassis via a wire coming out from the top of the relay. This caused the indicators on the dash to constantly flash. They would occasionally go off if I had used the signals but would reactivate. The turn signals and hazards worked as they should when activated with the stalk or hazard switch, but the constant clicking drove me to try another solution.

I installed the WW flasher 211953227B unit (properly grounded case to chassis). And a new EL 13 relay. Now both dash indicators stay off during normal operation. When the stalk is used to indicate left or right, the exterior lights work fine, but both dash indicators will flash (and are very dim). Hazards work fine.

This is much better than either form I had before, but I still strive for perfect operation. Any ideas for something else to try?