When I turn on the headlights on, the left turn signal indicator on the dash goes on. If I put the indicator in the left hand turn position, the indicator light goes off but the left turn signal doesn't work on the left The right side is fine. If the headlights are off, both turn signals work fine. I checked and cleaned the ground to the front turn signal. The turn signal switch is about 3 months old and was working fine. Could it be a bad ground for the headlight? Thanks
Turn Signal Indicator on When Headlights are Turned On.
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Challenger RTA
Well-Known Member
Start checking the grounds, parking light and turn signal sockets. Bulb in backwards?
Just to be clear. You are saying just when the headlight are on. Not just when the parking light on?
Or both positions?
Just to be clear. You are saying just when the headlight are on. Not just when the parking light on?
Or both positions?
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Challenger RTA
Well-Known Member
Side marker light turn signal conversion
How to make side marker lights work with turn signals.
I always wondered why my coach came with just one side turn signal. I have a marker light mid way down the body but it's just a marker, no signal. I got replacement lights that are a combination marker/signal but, even though they dimensions were correct, they didn't fit the recess in the fender skirt. My next idea was to find a 3 wire socket. That didn't work either because the marker uses a 194 bulb and there is nothing equivalent to it in dual filament. I almost gave up until I found this webpage. The text of it is below. Basically, what you do is disconnect the ground of the marker light and hook it to the positive side of the turn signal. The marker light gets it's ground through the turn signal bulb. When the turn signal is on and the marker light is on, the marker light blinks opposite to the rear signal. When the marker light is off, they flash in sync. The hardest part was getting a wire to the turn signal feed. I plan to add a signal at the back of the coach so I have 3 turn signals down the side.
Cross feed method
Vehicles with 2-wire, bulb-type side markers have come from the factory two ways: with the front side marker bulbs wired across parking lamp feed and turn signal feed, which provides a flashing side marker, or wired across parking lamp feed and ground, which results in a non-flashing side marker. There's no rhyme, reason, or consistency to which vehicles have what; front side markers may flash with the turn signals, but they're not required to, so it's a matter of automaker whim; the Jeep Wrangler had flashing front side markers until 2003, non-flashing starting in 2004. It's pretty random and arbitrary. If your vehicle has two-wire front side markers with filament bulbs, and they don't flash with the turn signals, you can make them do so by moving one wire.
Here's how the front parking, turn signal and side marker lights are wired so the side markers do not flash:
This diagram shows the common "park/turn" bulbs, with a bright turn signal filament and a dim parking lamp filament in the one bulb. Each filament has its own feed terminal on the bulb base. The wiring is the same in systems that have separate bulbs for the parking lamp and the turn signal; the only difference is that the park lamp feed and the turn signal feed go to separate bulbs.
With this hookup, the side marker lamps are wired exactly like the parking lamps. They are always grounded, and they receive +12V whenever the parking lamps are on. Therefore, they illuminate steadily whenever the parking lamps are on, and never flash.
Here's how the system is wired to make the front side markers do double duty as side turn signal flashers:
There's only one difference between this setup and the non-flashing one: Instead of the side markers being wired across parking lamp feed and ground, they're wired across parking lamp feed and turn signal feed.
The side marker bulb socket is isolated from ground, and one bulb lead goes to the running lamp positive circuit. The other lead is tied into the turn signal positive lead.
When the parking lights are on and the turn signal off, it grounds through the turn signal filament and illuminates the marker lamp. When the turn signal flashes, it interrupts the ground and the marker will flash. When the running lights are off, the process is reversed, with the ground being through the filaments of the running light circuit, and the marker will flash in sync with the turn signal instead of alternately.
How to make side marker lights work with turn signals.
I always wondered why my coach came with just one side turn signal. I have a marker light mid way down the body but it's just a marker, no signal. I got replacement lights that are a combination marker/signal but, even though they dimensions were correct, they didn't fit the recess in the fender skirt. My next idea was to find a 3 wire socket. That didn't work either because the marker uses a 194 bulb and there is nothing equivalent to it in dual filament. I almost gave up until I found this webpage. The text of it is below. Basically, what you do is disconnect the ground of the marker light and hook it to the positive side of the turn signal. The marker light gets it's ground through the turn signal bulb. When the turn signal is on and the marker light is on, the marker light blinks opposite to the rear signal. When the marker light is off, they flash in sync. The hardest part was getting a wire to the turn signal feed. I plan to add a signal at the back of the coach so I have 3 turn signals down the side.
Cross feed method
Vehicles with 2-wire, bulb-type side markers have come from the factory two ways: with the front side marker bulbs wired across parking lamp feed and turn signal feed, which provides a flashing side marker, or wired across parking lamp feed and ground, which results in a non-flashing side marker. There's no rhyme, reason, or consistency to which vehicles have what; front side markers may flash with the turn signals, but they're not required to, so it's a matter of automaker whim; the Jeep Wrangler had flashing front side markers until 2003, non-flashing starting in 2004. It's pretty random and arbitrary. If your vehicle has two-wire front side markers with filament bulbs, and they don't flash with the turn signals, you can make them do so by moving one wire.
Here's how the front parking, turn signal and side marker lights are wired so the side markers do not flash:
This diagram shows the common "park/turn" bulbs, with a bright turn signal filament and a dim parking lamp filament in the one bulb. Each filament has its own feed terminal on the bulb base. The wiring is the same in systems that have separate bulbs for the parking lamp and the turn signal; the only difference is that the park lamp feed and the turn signal feed go to separate bulbs.
With this hookup, the side marker lamps are wired exactly like the parking lamps. They are always grounded, and they receive +12V whenever the parking lamps are on. Therefore, they illuminate steadily whenever the parking lamps are on, and never flash.
Here's how the system is wired to make the front side markers do double duty as side turn signal flashers:
There's only one difference between this setup and the non-flashing one: Instead of the side markers being wired across parking lamp feed and ground, they're wired across parking lamp feed and turn signal feed.
The side marker bulb socket is isolated from ground, and one bulb lead goes to the running lamp positive circuit. The other lead is tied into the turn signal positive lead.
When the parking lights are on and the turn signal off, it grounds through the turn signal filament and illuminates the marker lamp. When the turn signal flashes, it interrupts the ground and the marker will flash. When the running lights are off, the process is reversed, with the ground being through the filaments of the running light circuit, and the marker will flash in sync with the turn signal instead of alternately.
Sorry, I forgot to mention this is a 70 Barracuda. The turn signal/driving lights are a little different, There is a separate ground wire for the bulb housing. I'll check but I don't think the bulb is in backwards since I didn't remove it. The turn left signal indicator comes on also with the parking lights are on. I'm going to double check the ground. The weird thing is the turn signal indicator goes off when I turn the left signal on. The turn signal does not flash. If I turn the headlights off, the turn signals work. Thanks.
Challenger RTA
Well-Known Member
OK the top black and white is a in-general diagram of how the most turn signal switches are configured. The second color diagram didn't exist until I made it from other diagram. Or at lest I never seen one. It is the pin out of the turn signal plug under the column.
Unplug the connector. On the car plug apply power to each signal wire. that you want to check
last diagram to show the dash side wiring with the steering column connector and the Turn Signal Flasher (on the side of the ashtray).
By unplugging and applying power to each signal wire. This is a quick way to see were the problem is. Use power from Batt on the fuse box. Take note that is not fused. Use a test light to test. A light will have enough resistance if the is a dead short.
In the last picture.
If you have a front park and turn signal light that glows dim.
The bulb is in backwards or not quite locked in. The socket is shorting out. Sometimes you really have look at it to see it. And Yes now you can put a bulb in backwards now. Cheap Chinees crap.
In a perfect world. Sockets not rusted or inner parts not bad. Check the socket connections inside and plastic insulator. Look and see! I fixed this one.
View attachment 148594
Other things. The wiring is older. There could have been alterations to it over the years and now showing up. Plugs plugged in wrong. Loose or corraded connections, bulkhead connections, plug connections, broken wires inside insulation. It happens.
Unplug the connector. On the car plug apply power to each signal wire. that you want to check
last diagram to show the dash side wiring with the steering column connector and the Turn Signal Flasher (on the side of the ashtray).
By unplugging and applying power to each signal wire. This is a quick way to see were the problem is. Use power from Batt on the fuse box. Take note that is not fused. Use a test light to test. A light will have enough resistance if the is a dead short.
In the last picture.
If you have a front park and turn signal light that glows dim.
The bulb is in backwards or not quite locked in. The socket is shorting out. Sometimes you really have look at it to see it. And Yes now you can put a bulb in backwards now. Cheap Chinees crap.
In a perfect world. Sockets not rusted or inner parts not bad. Check the socket connections inside and plastic insulator. Look and see! I fixed this one.
View attachment 148594
Other things. The wiring is older. There could have been alterations to it over the years and now showing up. Plugs plugged in wrong. Loose or corraded connections, bulkhead connections, plug connections, broken wires inside insulation. It happens.
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Thanks, great info. I'll check out the testing the circuits tomorrow.
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