Turn signal won't blink with headlights on

[Brownie82C10]

I have a 1982 Chevy C10. I replaced a blown front-right (passenger-side) amber turn-signal/marker bulb today, using a 1157NA as the replacement bulb. (The bad one was a 2057NA.) Later on, while checking all of my lights, I noticed that with the right turn signal on and the headlights on, the replacement bulb burned brightly (both filaments) but didn't flash. When I turned the headlights off, the signal bulb flashed like it's supposed to. Everything is OK with the signals in the back and on the front left. Could the problem here be a bad ground? Thanks.

 

[Turbo4whl]

I have a 1982 Chevy C10. I replaced a blown front-right (passenger-side) amber turn-signal/marker bulb today, using a 1157NA as the replacement bulb. (The bad one was a 2057NA.) Later on, while checking all of my lights, I noticed that with the right turn signal on and the headlights on, the replacement bulb burned brightly (both filaments) but didn't flash. When I turned the headlights off, the signal bulb flashed like it's supposed to. Everything is OK with the signals in the back and on the front left. Could the problem here be a bad ground? Thanks.

Yes, could be a bad ground. Could also be the bulb was installed 180 degrees backwards. Long side pin reversed and installed where the short retaining pin should be. New lamp socket will not allow the bulb to be installed wrong. A 28 year old socket will be loose, and you sometimes can install the bulb wrong.

If the socket has been replaced, it may be wired incorrectly.

 

[Brownie82C10]

Thanks. I'm checking first for a bad ground. The socket seems to be OK -- though I can tell by the wire colors that it's an aftermarket replacement (apparently replaced by the previous owner) -- and the bulb seems to be seated properly. The front-right turn signal lights (front and side) work just fine -- as long as the headlights aren't on.

 

[Brownie82C10]

Happy New Year, everyone. OK, so I checked the ground from the bulb harness, and it appears to be good. That's not the issue here. What else can I check, or do I just go ahead and replace the turn signal bulb harness (socket) with a new one? Again, the turn signal on the front right works until the headlights are turned on, and then both filaments in the bulb light up -- with no blinking. The side marker light on that side works just fine in signal mode with the headlights on or off. Thanks.

 

[jjester6000]

I have a 1982 Chevy C10. I replaced a blown front-right (passenger-side) amber turn-signal/marker bulb today, using a 1157NA as the replacement bulb. (The bad one was a 2057NA.) Later on, while checking all of my lights, I noticed that with the right turn signal on and the headlights on, the replacement bulb burned brightly (both filaments) but didn't flash. When I turned the headlights off, the signal bulb flashed like it's supposed to. Everything is OK with the signals in the back and on the front left. Could the problem here be a bad ground? Thanks.

I have literially the exact same issue on my '98 Suburban. I found there to be some crossover with the marker lights circuit and brights circuit.

With the regular lights on it would blink slow since the Brights on this particular truck are dimly powered when the headlights or on.

When I have the full brights its just solid, so for now I just removed the drivers side bright bulb and it seems to have fixed the issue.

 

[Brownie82C10]

I'm wondering now if the issue might have to do with mismatched signal bulbs on the front left and right. I have an older (and dimmer) 2057NA bulb on the front left and a new 1157NA on the front right. I have some more 1157s on mail order. After they're delivered, I'll match up the bulbs on the left and right and see what happens.

 

[WebMonkey]

Thanks. I'm checking first for a bad ground. The socket seems to be OK -- though I can tell by the wire colors that it's an aftermarket replacement (apparently replaced by the previous owner) -- and the bulb seems to be seated properly. The front-right turn signal lights (front and side) work just fine -- as long as the headlights aren't on.

mine did this until i replaced the two front sockets and wired all 4 markers correctly.

it had been wired up wrong and behaved just like yours.

i'm not saying you have to replace sockets, just that the marker lights run in/out of each other rather than each marker having a discrete connection to + and -.

good luck!

 

[Turbo4whl]

Since you stated the bulb socket is okay, then you still have a ground issue.

I'll use another example to explain how this could be. The fender side marker lights do not have a two filament bulb but they still blink with the turn signals when everything is correct. They do not have a dedicated ground. Instead they are fed with two hot wires, How does this work?

One wire feeds from the parking lamp circuit, the other feeds from the correct side turn lamp. When just the parking light circuit is on, currant feeds from the bulb filament to the signal side, then through the turn signal bulb filament to ground. Since only a small amount of amperage is needed for the 194 bulb it does not light the signal bulb.

When the parking lamps are off and you use the turn signal the side marker lights up and grounds through the rest of the parking light circuit.

When the parking lights are on and you use the turn signal. the fender marker blinks off, two positive feeds on at the same time.

Now to your issue. Since you stated the turn lamp gets brighter when the headlights are on, this can only be one of two problems. One, the headlight wire is shorted to the turn wire, or you have a ground issue. Since all of the same side front lights ground on the same bolt, one or all of the grounds is open. This allows the headlight current to light the turn lamp. Then finds whatever different path to ground.

Two last questions, when you checked the turn lamp socket you have a ground, correct? Did you turn the headlights on to see if you still have a ground, or maybe now it is positive with the headlights on?

 

[Brownie82C10]

The problem is fixed, and the solution turned out to be simple. I simply replaced the 1157NA signal bulbs on both sides in the front with matching new bulbs. Now, the turn signals blink on both sides with the headlights on or off.

 

[BradWebb]

My issue was a dim left headlight and left signal would not blink, left signal indicator stayed lit. turn off headlights, signals worked fine with park lights on or off.

After reading a few comments on i found a bad ground near left headlight. hope this helps someone else