Turn Signal Problems

[OldBlue88]

I have a 1988 K2500. When the parking lights are on, the passenger side front turn signal is on bright as if blinking but on steady bright. The driver side is normal. Left signal works fine, right turn does not. I have checked all the wiring under the truck, installed new rear light fixtures and replaced the multi-function switch. The truck had multiple trailer plugs and I cut all that out and wired everything back stock. Does anybody have any more suggestions?

 

[Nad_Yvalhosert]

You've got a ground wiring issue. Sounds like the (headlights off) bulb is using a different path to ground, likely through the parking light circuit.

Check the black wire that goes to an eyelet on the fender behind the battery.
Unwrap the conduit and check the crimps on the grounds too.

There's only one rear ground. If the problem was in the rear, it would affect both rear, not just the passenger side.
If you disconnect either rear tail light, it should hyperflash.

Question: You are sure the correct 1157 & 3157 bulbs are installed? You dont have LED's in do you? They're polarity sensitive...

 

[GoToGuy]

Check to be sure you correct bulb numbers. Are you sure the other side isn't dimmer. Front bulbs only one filament, so if it looks alot brighter you may have incorrect wattage bulb. You didn't mention if the turn flasher is functioning normally? What exactly happens when you select right turn signal?

 

[Nad_Yvalhosert]

Check to be sure you correct bulb numbers. Are you sure the other side isn't dimmer. Front bulbs only one filament, so if it looks alot brighter you may have incorrect wattage bulb. You didn't mention if the turn flasher is functioning normally? What exactly happens when you select right turn signal?

"Front bulbs only one filament" Huh? One filament? Marker lights and turn signals have two filaments. 1157 bulbs, (and 921 side markers).

The signal flasher HAS to be operating properly, it's upstream of the left/right switch. That why there's ONE signal flasher, NOT a left flasher and a right flasher.

His 3rd sentence clearly states:
"The driver side is normal"

 

[OldBlue88]

You've got a ground wiring issue. Sounds like the (headlights off) bulb is using a different path to ground, likely through the parking light circuit.

Check the black wire that goes to an eyelet on the fender behind the battery.
Unwrap the conduit and check the crimps on the grounds too.

There's only one rear ground. If the problem was in the rear, it would affect both rear, not just the passenger side.
If you disconnect either rear tail light, it should hyperflash.

Question: You are sure the correct 1157 & 3157 bulbs are installed? You dont have LED's in do you? They're polarity sensitive...

Thanks for the reply. I did make sure to have the correct bulbs. The tail light assemblies came with the bulbs in them when I bought them new. I don't have LED's. I did have some paint work done where the bed was taken off, the bumpers taken off and all of the lights taken out. I will check the grounds.

 

[OldBlue88]

Check to be sure you correct bulb numbers. Are you sure the other side isn't dimmer. Front bulbs only one filament, so if it looks alot brighter you may have incorrect wattage bulb. You didn't mention if the turn flasher is functioning normally? What exactly happens when you select right turn signal?

I also replaced the flasher. When I select the right turn signal with all the lights on, nothing changes. When I turn all the lights off and operate the right signal, all four lights blink as if I have my hazards on. The left still operates normally.

 

[Nad_Yvalhosert]

I also replaced the flasher. When I select the right turn signal with all the lights on, nothing changes. When I turn all the lights off and operate the right signal, all four lights blink as if I have my hazards on. The left still operates normally.

That sounds like a bad socket or bulb installed incorrectly. Think about it... the power goes from the turn signal switch on the column

out to the right signal wiring

through the bulb, lighting it up

across the socket, bypassing the ground

backfeeding through the parking light wiring

over to the left side

across the filaments in the driver side bulbs, lighting them up

then to ground on the driver side.

 

[Nad_Yvalhosert]

I also replaced the flasher. When I select the right turn signal with all the lights on, nothing changes. When I turn all the lights off and operate the right signal, all four lights blink as if I have my hazards on. The left still operates normally.

Now, that would only work that way with parking lights off.
With the parking lights on, you send turn signal voltage to the right turn signal, and already have power to the parking light. It won't flash because you dont have ground to right turn signal, but the parking light ground backfeeds to driver side.

 

[Nad_Yvalhosert]

Turn on your lights and right turn signal. By your description the left should be flashing as well.
Remove the right lens and remove each 1157 bulb, one at a time and see if the left stops flashing

 

[Nad_Yvalhosert]

Lastly, try switching the left side 1157's and the right side 1157's. If the flashing/non flashing issue changes sides, you have defective bulbs. If it doesnt, suspect defective sockets.