Turn signals work, but won't blink!

[John Fauerbach]

Here it is...during a parade a woman rolled into me (I had no place to go, but into spectators). I replaced left tail lenses and license plate lamp assembly. Now (related or not?) My turn signals light (all 4), but won't blink. My hazard lights will also come on, but will not blink. I replaced the relay under the front hood (C-31-49-49A) but it made no difference. I checked fuse number 11, no difference. Although none of my books show it I've read there is a hazard relay behind the dash, on the left, near the radio or behind the gauge to the left of my tach. Clearly I am getting power everywhere, because the lights light. Clearly my problem is a blinker switch or relay. Clearly it’s not the one I changed out. HELP! I have no idea what to check. As for the other relay, my books show no pictures, plus they refer to the unit as the hazard relay and the emergency blinker relay (?) and I am not even sure this is my problem. If anyone has any suggestions other than sell my SC please help me! I have a beautiful mostly original 1978 911 SC (86K...had to brag). John P.S. I used to work on British cars, am used to electrical problems, but this one has me stumped.

[timmy2]

My '78 SC (with 81.5K.... Sorry I just had to... ) has a relay behind the oil gauge. I believe this is it:
Pelican Parts - Product Information: 914-618-303-11-M44

[Skip1]

I have a similar issue that I'm trying to resolve (although I have a Euro '84 Targa it's the same blinker relay posted already) and although mine is intermittent, the signals go solid on one side periodically / as does hazard light switch without blinking - may be linked to heat in my case (overheating in the dash area). Am working through that issue, and have also replaced the relay on the left behind the gauges to no avail. I'll try to post something if I figure my issue out - could be related.

[John Fauerbach]

The books are a bit vague...how do I access this other relay? If I remove the oil guage, please what is your best procedure?

[John Fauerbach]

My books are not clear, actually they're confusing. What would you recommend as the best procedure for changing out that relay???

By the way, my shop manual (over $100.00) actually referred me to a page with a picture listing the relay and a note saying the relay was not shown in the picture. I'd love to have a one on one conversation with whomever thought that would help.

John

[John Fauerbach]

Is there away to do a meter check to determine if the relay is good or bad???

[John Fauerbach]

Is there a way to check the relay to see if it is good or bad???

[Skip1]

You must have a Bentley manual - mine is the same. The attached picture (compliments of our host) shows the emergency / turn signal relay (p/n: 914-618-303-11). It's hard to show on a picture, but it sits in a plug that "should" be connected with a rubber grommet to the body - small nib holds it in place, although it can easily be popped out. If you take your oil / fuel gauge out, looking straight in the round hole, it is slightly left and sits about 4-5 inches in. It could be laying down (as mine was when I got the car). On my car there is no relay under the hood (in luggage compartment fuse panel) that affects the blinker mechanism that I can tell. You may have to feel around for the plug end and the square relay - others have commented in other posts about finding it tucked under ducting etc. As for testing the relay, I'm not sure, as I don't have a schematic of the inner workings, however hope this helps:
(1) power goes in on pin 49 (from fuse 8 if hazard switch is off or fuse 2 if it's on)
(2) pin 49A I believe is the pulse sent out (clicking signal) that goes to pin 49A on the has switch and onward to the turn signal switch in the column
(3) pin 30 goes to ground
(4) pin C goes to the tachometer apparently for a trailer indicator (although I'm not sure on this one.


I've also taken a further look at my challenge which could be directly linked to either your problem or mine I believe. These teutonic designed vehicles are notorious for their corroding electrical connections, and am wondering if the two ground connections (pictures enclosed) could be the problem. I have already cleaned G104 (on the fender), but not sure it actually is used by the turn signal system. The other G116 is behind the master brake cylinder and below multiple wire sets. I'll attack this in the next couple of days to clean it as it does appear corroded. I'd try to ensure these two points are cleaned up (particularly G116), as it could be that easy.

[Mysterytrain]

My 2 cents: I decided I needed brighter turn signal indicators [inside] because with the targa top off they are difficult to see in sunlight. I went with a pair of Etarga's Green LED's but couldn't get them to work correctly so I began to research the hazards/turn signal circuits. The information gathered from pelican postings on the subject point to the fact that the 30 yr old design and OEM mechanical flasher relay seems to be very sensitive to bad grounds and the resistance of the interior and exterior bulbs. Over time the sockets and the grounds are not functioning as per the original design and I would imagine that the current production of bulbs also differ in resistance from what was manufactured 30 yrs ago. Anyway, add all these small changes together and we wind up with big problems.
In addition to the LED issue I had one other oddball problem that I couldn't resolve with the OEM bulbs; when I pushed the hazard switch the exterior lights flashed but the interior turn signal indicators wouldn't flash. Even a new Hella flasher couldn't cure that problem.
I read a posting by Kroggers on how he fixed his LED turn indicator issue:
I solved the LED indicator problem!!
Interesting I thought, but he's from Finland what do they know about electric in the states. I also stumbled onto a 1985 schematic and noticed that the factory moved from the 4 pin relay to a 3 pin relay..the wiring was the same as Kroggers and eliminated the use of the 'C' terminal in favor of a direct ground. Hmm, maybe he was onto something.

I hit the Autozone website and found LED compatible electronic relays..marked euro style with pins 31, 49 and 49a. So I decided to invest the $13 and give it a go.
Well, boys it worked..the hazard/turn indicator issue was solved. I decided to move onto the LED indicator problem and swapped out the two interior bulbs. Bingo, I'm in business and everything works, the turn signal indicators are blinding!
Materials used:
Autozone Flasher EP36
Replaced the turn signal indicator plastic housings with 914 housings. My SC had the push-in type bulbs and the housing would not except the BA7 Bulb or Green BA7LED [ETarga offered up a pair of the 914 parts]. They were not a direct fit. I needed to turn them down on a mini-lathe to get them to slide into the holes on the tach.
As Krogger explained in his post and as the 1985 schematic shows you still need to ground the bulbs or LED's to the tach because you are not using the 'C' connection harness. I taped up the harness and left it behind the dash in the event I wanted to return the circuit to its original configuration. I used a few inches of BROWN wire to ground the LED's and attached the lug to the ground connections on the back of the Tach.
So, long story short..I would recommend swapping out the mechanical relay for an electronic version that is LED ready and less sensitive to the circuit resistance, plus they are cheap. You just need to remember that you need to fabricate a 3 terminal ground wire for the tach bulbs. I'm was on Hella's website and saw that they have electronic versions available but I was unable to locate them locally.
This fix is not going to cure hacked wiring, but I think itmight be the answer to mismatched bulbs, corroded sockets and the LED conversions.

[John Fauerbach]

Thank you for your help, but here's more info. The switch under my hood I replaced is the one with the 49, 49a, 31 and c connections. I have been told there is yet a second flasher relay located someplace else that also runs throuhg the same wiring. This I believe is the one I need to locate and change out. Does this make sense???? John

[Skip1]

While I'm no expert on 911 wiring (just a good ol' DIYer), I can't see that being correct. If you look at Ron's '85 schematic (it only has the one relay), and mine for the '84 is nearly identical (less the C connection that he explains as having changed in '85). I have also looked through an '86 wiring diagram from another member (not the Bentley manual, but original Porsche) and see no second relay anywhere. Also on the Porsche schematic I see the "C" pin going to "TRAILER TURN SIGNAL INDICATOR LAMP" although it doesn't indicate where it is (tach?). Wonder who mentioned a second relay to you John. I will be crawling under the dash tomorrow to see what I can find, and will try to get some decent pictures, if that's possible in that tangled mess of teutonic wiring... he he he). Today I drove the car out of the garage for the season and got caught in a sudden snow squall while travelling further north (yeah I know - what on earth for?), only to find my signal trouble still ongoing, so...

I must say I do like Ron's idea of LEDs ...

[Drisump]

Presumeably you changed out the bulbs when you did the work. The "standard" two filiment bulbs available everywhere (I believe 1057) do not work properly in a 911. You may find that after changing to OEM spec'd bulbs that everything is back to normal. It seems unlikely that another (unrelated) problem (relay) would crop up after the incident. Cheers.

[enzo1]

My car would blink 1 time then short out.... I finally found the "short" in the headlight bucket. Turned blinkers on, moved wires going to headlight and

[Skip1]

So I did a little more digging through my challenge and cleaned up the ground point (G116). This is tucked in just beside the luggage compartment strut on the driver's side.


I then proceeded to open up the steering column to access the turn signal switch and try to clean the contacts as best I could. Unfortunately they are not directly accessible due to a plastic riveted top. I used some electrical contact cleaner and a very small wire brush (about 1/16 of an inch in diameter to try to scrub them)


Also enclosed is a picture of my turn signal relay, tucked behind another one - hope that helps. So far my turn signal works again.

[Skip1]

So a follow up with a couple of pictures. The first picture is another view behind the gauges showing the turn / hazard relay and two unknown round black relays (any ideas?) It's an RoW vehicle so doesn't have a buzzer or seat belt warning system installed.

The next two pictures are from the cleaning of ground point G116. It was very awkward to get under all the wiring harnesses, so I used tie wraps to lift them up and attached them to the hood shock area. The area under the ground wires was quite corroded as well.


Hope they help.

[Mysterytrain]

I might have info on one of those black round relays.
At some point in time the factory had an additional circuit to operate the power windows when the ignition was turned off. If you opened the door the door switched triggered the relay behind the dash and sent 12 volts to the power window circuit allowing you to operate the windows without using the key. Of course, when the door is closed then the relay is de-energized. I posted the schematic of the circuit a few years ago.

[Skip1]

Thanks Ron. That is likely the one on the right, as I found the other one sitting lose below the wiring, so reinstalled it. Not sure what it did or didn't do, but the power windows definitely work with the power off / doors open or closed - so you may be right. I hate not knowing what things do - especially when things work (or at least appear to work) even when parts are absent...

[Mysterytrain]

Glad that helped...I've never seen that 'extra' relay in any of the window circuit schematics. It might have been a one or two year thing before they went to an electronic controller for the windows. I bought the harness on ebay and then tracked the part number down to the PET.

[Hoss911sc]

FWIW I had an issue with mine that turned out to be a loose wire on the bottom of the fuses for the turn signal. You may have checked that already.

[Skip1]

You'd think so wouldn't you, but no....

So for my issue, I noted two things:
(1) the green / red wire running out of the base of fuse #8 to the hazard switch was protruding somewhat so could have been grounding I guess - not sure if that could could this issue
(2) fuse #2 was out of alignment on an angle (now corrected).

Unfortunately, neither of these issues solved the problem. As of today, it appears that the problem is no longer intermittent, which is good from a troubleshooting perspective I guess.
So, this afternoon I did a little bit of fiddling while the problem remained extant, pulling each fuse in the Exterior Light circuit in order to eliminate various parts of it. With the exception of Fuse #2 and #8 which directly power the signal and hazard lights stopping everything, no removal of any other fuse changed the problem. This now takes me away from all the lights themselves (both front and rear of the car), and isolating the problem to the turn signal switch, relay and associated wiring as well as the light switch based on the standing light option my car has. If it persists after dinner, I'm back at it to pull connections and continue.

Does my analysis make sense?