Signals work when headlights turned off but not on..

[lkfldredneck]

So i went to check if my signal lights were working after i did the rad support to see if i need new lights after they jumbled around a bit. and noticed the signals work when the headlights are off, but dont work when the headlights are on.

The flasher goes the same way, doesnt work with the headlights on but works without them on. what could it be?

Its been a long boring day at work and i really dont want to think about rewiring a fair bit of it so i hope its simple!!

[ray_mcavoy]

Check the connections where the ground wires for the headlights & turn signals attach to the radiator support. Also check the negative battery post to radiator support / sheetmetal ground. All of these connections typically use a ring terminal secured to the radiator support with a bolt. If any of those connections are loose or rusty/corroded they could be causing the problem you're experiencing.

[lkfldredneck]

Originally Posted by ray_mcavoy

Check the connections where the ground wires for the headlights & turn signals attach to the radiator support. Also check the negative battery post to radiator support / sheetmetal ground. All of these connections typically use a ring terminal secured to the radiator support with a bolt. If any of those connections are loose or rusty/corroded they could be causing the problem you're experiencing.

Ok, Ill check that tomorrow but when i put a new rad support in, i tried to scratch off enough paint to get a good ground, might not have scratched enough paint off though. ill clean up all the grounds tomorrow after work and see if that works

['76 Big Block]

I had the exact same problems after I replaced the right fender and battery tray on my '76.
My problem turned out to be one of the wires had an insulated terminal, and when I reinstalled the ground wires, the washer was on top of the insulator, giving me a poor ground connection. Once I trimmed the insulator and retightened, everything worked.
Good Luck!

[lkfldredneck]

Originally Posted by '76 Big Block

I had the exact same problems after I replaced the right fender and battery tray on my '76.
My problem turned out to be one of the wires had an insulated terminal, and when I reinstalled the ground wires, the washer was on top of the insulator, giving me a poor ground connection. Once I trimmed the insulator and retightened, everything worked.
Good Luck!

Thanks for the info! Ill look at that too.

[lkfldredneck]

Cleaned up the grounds on the rad support (Minus the ground that went to the frame from battery) and the signal still doesn't work with headlights on. Looks like someone put a wire into the cab for something that's connected to one of the wires on the truck, ill take a look later this week when and if i have time. Could someone post a picture of a headlight + taillight wiring diagram? Ill be looking in the meantime

[cadillac_al]

Check your tail light wiring. There is usually a jumbled mess of wires that someone messed with in the past. I'm pretty sure there is a ground back there too.

[lkfldredneck]

Originally Posted by cadillac_al

Check your tail light wiring. There is usually a jumbled mess of wires that someone messed with in the past. I'm pretty sure there is a ground back there too.

Ok thanks, the running lights for the taillights dont work so that might be the problem too.

[hatzie]

Originally Posted by cadillac_al

Check your tail light wiring. There is usually a jumbled mess of wires that someone messed with in the past. I'm pretty sure there is a ground back there too.

The Fleetside bed tail lamp grounds are behind the tail lamp housings direct to the bed sheet metal. The stepsides originally had a ring terminal screwed to the bed sheet metal close to the lamp housings. Stake bodies are anyone's guess.

[lkfldredneck]

Well i ripped that random wire off because, well it went no where. The wire is kinda chewed up so it doesnt probably ground the best. Possibly will be having the day off tomorrow so if i do i will connect that wire with a crimp connector.

Does anyone know if i could ground each light to the rad support? cause if so that would be a lot easier than chasing wires.. Just ground everything seperately instead of running to one big ground (Need new pigtails for the sigs anyways)

[lkfldredneck]

So after countless hours grounding, finally i found the problem.

The PO had Red LED 1157 bulbs in place where the signal/Brake light goes.

Sure, LEDs are cool and last longer. But Not If They Dont Work!!

Swapped out with some good old original 1157s and BAM! They work great. One less problem solved!

[TKCR]

Originally Posted by lkfldredneck

So after countless hours grounding, finally i found the problem.

The PO had Red LED 1157 bulbs in place where the signal/Brake light goes.

Sure, LEDs are cool and last longer. But Not If They Dont Work!!

Swapped out with some good old original 1157s and BAM! They work great. One less problem solved!

I tried LED's too, they don't work very well. They caused all kinds of weird issues. I went back to the "good old original" bulbs and no more issues.

[Front Range]

That got me curious - found this info on the web:

When converting a vehicle for use with LED Turn Signal bulbs, it is often not enough to simply replace the regular incandescent bulbs with LED bulbs. In many cases, you will have to either replace the car's flasher module, or trick the flasher module into thinking that there are "regular" bulbs in your car...

...and here is why:

An LED bulb only consumes a very small amount of electrical current. The turn signal flasher (if it's a regular "thermal" flasher) was designed for bulbs that consume a lot of power: The power consumed by the bulb runs through the flasher and heats up a bimetal switch. When the bimetal deforms from the heat, it breaks the circuit (causing your lamp to go off), this causes the switch to cool down and go back to it's original shape (it will close the circuit again, the lights come on, the switch heats up, and the cycle begins again).

If the amount of power going though the switch is very little, not enough heat is generated in the flasher to cause the bimetal to bend. The most common symptom is that your turn signal lights simply stay on. If you run a MIX of regular and LED bulbs (say regular in the front, LED in the back), you may not notice it but if your incandescent bulb breaks, you're back to nothing-flashing.

Other symptoms are fast flasher, slow flashing or not coming on at all.



There are usually two solutions:

Install Load Resistors: these resistors basically a resistor that consumes enough power to cause the stock flasher module to kick in. Your flasher basically doesn't know that you're running LED bulbs. This is usually the more expensive solution, creates a lot more work and just generally undesirable. However, this may be what you have to do if you cannot find an LED-compatible flasher.

LED-Compatible Flasher: This will work on most cars (and the older the car, the more likely), and usually means ripping out the stock flasher and putting in an LED-compatible replacement. Sometimes you may have to flip some wires (and you can find harnesses to make that really easy). There are various different models of LED compatible flashers, and there are also different types.

Getting the right MODEL: Simple enough, the LED-compatible flasher should have the same number of prongs, pin-out and size/shape (square vs round) as your existing flasher. Sometimes, LED compatible flashers have an additional wire coming out of the top of the flasher, that just needs to be attached to the car's ground.

Getting the right TYPE: Some LED flashers will work ONLY WITH LEDs and will go up in smoke when you put incandescent bulbs (or a mix of LED and incandescent) into your lights. Those flashers should be stayed-away from. There are also SOLID STATE flashers, those don't use a relay, have an extremely long life (because they don't have any mechanical parts), are more expensive and usually do NOT make a clicking noise.

Hazard Flasher: Some cars have two flashers, one for hazard lights, another for turn signals. They may or may not be different models, but you will have to replace both.

[TKCR]

I tried the Flasher module, that didn't work. It probably did need the load resistors, I just didn't want to mess with it. I was afraid of causing more issues than what it was worth.
Posted via Mobile Device

[hatzie]

Several issues at play.
The correct flasher will make LED tails work. Easy fix. Get an electronic flasher NAPA 552 or Signal Stat 262.

Not the whole story.

If you pay attention you'll notice the front side marker lamps flash on the off part of the flash cycle. The 194 side marker lamps don't have a ground they are wired across the two hot wires on the the 1157A front bulbs. 194 and or 1157A LED bulbs will not function wired in this manner. If you want LED bulbs up front you'll need to clip the turn signal wire that runs to the side markers and attach it to a good ground.

[lkfldredneck]

Thanks for the info on Leds guys, i knew for newer cars cause my buddies have done them in their cars but all they needed was an led flasher. Anyways im glad i got the problem figured out