Turn signals and flasher don't work when headlights are turned on

[Bmachine]

During daylight, my turn signals / blinkers and emergency flasher work just as expected.

But I noticed that, at night (or in the fog) as soon as I pull the headlights switch on, even just in the first position, the turn signal/flasher lights come on solid and stay on. Activating the turn signal stoalk or pressing the flasher light don’t do anything anymore.

Search on the forum seem to bring up the issue of the 2 wires (in addition to the ground) that go into the front turn signal assembly but without definitive conclusion on how it might affect this issue. My wiring diagram shows only one wire (blue-red on LF, blue-black on RT) going to the turn signals. On top of that, the bulb itself only has one contact at the bottom and it seems to bridge the 2 pins of the bulb holder. So it should not matter which wire goes to which spade.

Does anyone know what would cause the headlight switch to kill the flashing action?

 

[jmackro]

During daylight, my turn signals / blinkers and emergency flasher work just as expected. But I noticed that, at night (or in the fog) as soon as I pull the headlights switch on, even just in the first position

Bo:

One of your tail or parking light light housings may not be well grounded. If that's the case, the turn signals have to find a path to ground through the housing and back through parking, back-up or brake light circuits. But with the parking lights on, that path to ground goes away and at least one corner of your car no longer has an operable turn signal bulb. The loss of the amperage from that disabled bulb through the flasher stops it from flashing.

Try jumpering each of the four light housings to a good ground while the e-flasher and parking lights are on, and see if that changes things.

 

[Bmachine]

Bo:

One of your tail or parking light light housings may not be well grounded. If that's the case, the turn signals have to find a path to ground through the housing and back through parking, back-up or brake light circuits. But with the parking lights on, that path to ground goes away and at least one corner of your car no longer has an operable turn signal bulb. The loss of the amperage from that disabled bulb through the flasher stops it from flashing.

Try jumpering each of the four light housings to a good ground while the e-flasher and parking lights are on, and see if that changes things.

Great suggestion. I will try that. Thanks Jay

 

[Bmachine]

Ok. Progress. Sort of...

I checked all grounds as suggested by Jay. All were in perfect order. I tested with ohmmeter and, for good measure, also ran a separate wire from another ground location. All connections good.

I had always been puzzled by the fact that the front turn signal housing has 2 wires coming in. Blue-red and grey-yellow on the LF side. My schematic only shows one wire coming in. There is however a grey-yellow (GR-GE) going into the low beam light. So it seems to continue onto the turn signal for some reason.



The bulb I have (which came from Walloth Nesch) only has one contact at the bottom and it seems to short the 2 connectors when it is installed



Note that my original bulb holder broke so I had to replace it with this newer version. But the original had similar 2 pins:



So I decided to remove the bulb to see if that made any difference. And sure enough that made the blinker work correctly, at least on that one side. Since the front bulb was out, that meant that the rear now worked as it was supposed to.

So I decided to take some measurements to see what these 2 wires do.

Ignition on, lights off:
Grey-yellow: 0 V, Blue-red: 0 V

Ignition on, lights on:
Grey-yellow: 12 V, Blue-red: 0 V Makes sense since grey-yellow also goes to low beam headlight

Ignition on lights on blinker on
Grey-yellow: 12 V, Blue-red: flashing 0 to 12 V

Since that grey-yellow wire has constant 12v as soon as the lights are turned on and since the bulb shorts out these 2 contacts, it's no wonder the turn signals stay on.

So:
- Why is grey-yellow headlight wire also coming into the turn signal? I am guessing it is for the parking light option. (Does anyone ever use that?)
- Is the bulb supposed to short both of these wires, therefore rendering the blinking part inoperable? That doesn't make sense. I am guessing that this is where the problem is. The turn signal bulb should have 2 independent contacts going to 2 different filaments which can be activated individually. One for the blinking, one for the parking light.

Does that make sense?

 

[nosmonkey]

Parking light pulls power from the steering column, there is a wire in the column that from memory that feeds 12v into the turn signal switch with the key removed, however this turns on the left or right side lights not the indicator. Either disconnect the low beam wire from the dual filament holder if you do not wish for front turn signals to be illuminated or run a twin filament bulb and all should be well!

 

[Stevehose]

Could it backfeed through a faulty light switch? If so, there is a rebuild thread - easy.

 

[jmackro]

The turn signal bulb should have 2 independent contacts going to 2 different filaments which can be activated individually. One for the blinking, one for the parking light. Does that make sense?

Yes, that makes perfect sense. You have 1156 bulbs in the two front sockets (single filament) and should have 1157 (two filaments). Install 1157's (available for a few bucks at your local AutoZone) and you should be good.

 

[Bmachine]

Excellent. Thanks very much Jay!

 

[ScottAndrews]

Parking light pulls power from the steering column, there is a wire in the column that from memory that feeds 12v into the turn signal switch with the key removed, however this turns on the left or right side lights not the indicator. Either disconnect the low beam wire from the dual filament holder if you do not wish for front turn signals to be illuminated or run a twin filament bulb and all should be well!

Not totally familiar witht he E9 wiring, but n the Euro E24, the turn signals can be activates withouit blinking when the ignition is off and the slat lever is pressed. This s that feature you often see in Europe where parked cars hava soft glowing turn signbal active on the street side.

Bo. I thin you should be using dual fliamnet bulbs one witha bright filament and the other with a low wattage filameny (e.g. 2 watts). Thans should fix the problema nd give youthe cool Euro parkign lamp feature.

 

[nosmonkey]

Not totally familiar witht he E9 wiring, but n the Euro E24, the turn signals can be activates withouit blinking when the ignition is off and the slat lever is pressed. This s that feature you often see in Europe where parked cars hava soft glowing turn signbal active on the street side.

Bo. I thin you should be using dual fliamnet bulbs one witha bright filament and the other with a low wattage filameny (e.g. 2 watts). Thans should fix the problema nd give youthe cool Euro parkign lamp feature.

Euro parking lights will bring left or right side lights on, not the indicator

 

[ScottAndrews]

Euro parking lights will bring left or right side lights on, not the indicator

Yes, that's true. But it is one reason for having two filaments in the turn signal lamp. One is driven by the flasher, and the other is just powered at a low level when the ignition is off and the lever is pressed right or left. But I think this is mainly a Euro thing.

I think in the US E9, however, the second filament is a parking lamp. Using a single filment bulb the two contacts are shorted together. When the lights are off, the parking lamp contact is open circuited, so it has no effect. However, when the lights are on, the parking lamp contact is positive. This illuminates the filament in the bulb, but that filament is not drawing current through the flasher. The flasher flashes because the current drawn through it heats up a bi-metallic strip. When that strip gets hot it clicks over to one side, opening the circuit and the light goes off. it then cools and flips back to the other side, closing the circuit, and so on. If there is no current though it, or not enough current though it, then it doesn't flash.

 

[Bmachine]

Yes, that makes perfect sense. You have 1156 bulbs in the two front sockets (single filament) and should have 1157 (two filaments). Install 1157's (available for a few bucks at your local AutoZone) and you should be good.

The 1157’s arrived yesterday (thank you Amazon one day delivery) and sure enough, they solved the issue. One has to be careful to wire them correctly as one filament is brighter than the other.

Thank you Jay!

 

[ScottAndrews]

The 1157’s arrived yesterday (thank you Amazon one day delivery) and sure enough, they solved the issue. One has to be careful to wire them correctly as one filament is brighter than the other.

Thank you Jay!

I believe the bright one is the turn signal

 

[ScottAndrews]

I believe the bright one is the turn signal...

You get one day Amazon way out there at the edge of the continent?

 

[jmackro]

The 1157’s arrived yesterday (thank you Amazon one day delivery) and sure enough, they solved the issue. One has to be careful to wire them correctly as one filament is brighter than the other. Thank you Jay!

Bo:

Happy to help. I enjoy solving these puzzles, though I have to admit that I never would have guessed that there was an 1156 bulb in a socket designed for 1157's.

The two studs coming out of the sides of the bulbs' brass bases differ between the two types: they are at different heights on the 1157 to ensure that you get the bulb oriented properly (i.e., with the brighter filament connected to the turn signal circuit). See the photo below - 1157 on left, 1156 on right. So how a 1156 would have even fit into a 1157 socket is still a mystery.

 

[Bmachine]

I believe the bright one is the turn signal

Correct

 

[Bmachine]

Bo:

Happy to help. I enjoy solving these puzzles, though I have to admit that I never would have guessed that there was an 1156 bulb in a socket designed for 1157's.

The two studs coming out of the sides of the bulbs' brass bases differ between the two types: they are at different heights on the 1157 to ensure that you get the bulb oriented properly (i.e., with the brighter filament connected to the turn signal circuit). See the photo below - 1157 on left, 1156 on right. So how a 1156 would have even fit into a 1157 socket is still a mystery.

Mystery indeed. I checked the old bulbs that were there when I first got the car and they were the 1156 also

BTW, on the Philips ones I got, the “shorter” filament on the left pic in your post is the brighter one. That one should be connected to the flashing signal