Turn signal Question 1972

[67Mach1]

I am trying to get one of my trucks inspected so I can finally get it on the road, but having one small problem with the turn signals.

W/out the headlights on they seem to be working just fine. I turn the headlights on to then use the signals and thats where the problem begins. The RH side functions correctly. the LH side the rear works perfectly. The front turn signal is a different story.

With the HL on the bright(er) light is on in the TS bucket and not the dim(er) one. SO when I hit the turn indicater to the left it's like the wiring is reversed, the bright stays on and it seems to flicker ever so slightly like the dimmer light is coming on. I traced the wiring and it seems alright, no cuts nor abrasions that I can find that might be the cause.

As I write and think about this perhaps the lamp was in incorrectly to begin with? Is it a wiring issue with headlight switch?


Anyone have this same thing happen or ever seen this before?

Thanks,
Thomas

[Longhorn Man]

if they work fine with the headlights off, then they are probably installed and wired properly.
I would start with cleaning the grounds on the core support, and making sure the core is grounded with a strap or wire from the frame of battery. Added bonus, your headlights will be brighter.

[Wrenchbender Ret]

Your left front turn light is not grounded. Clean the area behind the mounting bolts or run a ground wire from one of 6the studs to the truck body.

[67Mach1]

Originally Posted by Wrenchbender Ret

Your left front turn light is not grounded. Clean the area behind the mounting bolts or run a ground wire from one of 6the studs to the truck body.

I have not checked the ground on the turn signal, but I did swap the wires and the dual element lamp works just fine.

It was with Jumpers so nothing has been cut and can put it back to test the ground issue.

After taking the lens off it was obvious the brigher element was on as the parking element and the dimmer element was flashing. I did notice that the passengers side unit must have been the same way as someone prior to me swapped the wires on the front side of the firewall.


So if I understand what both are saying the unit not being grounded could cause the wrong element to illuminate?

[67Mach1]

Originally Posted by Longhorn Man

if they work fine with the headlights off, then they are probably installed and wired properly.
I would start with cleaning the grounds on the core support, and making sure the core is grounded with a strap or wire from the frame of battery. Added bonus, your headlights will be brighter.

Ill check the grounding issue, but with both sides TS lens off it was obvious that on the dual element lamp the bright element was illuminating on the LH side while the Dim element was on on the RH side with the headlights on. The unlit element then illuminated with the turn signal activated for either side. It was barely noticable on the LH side. Swapping the wires with jumpers fixed the problem.

Ill check the grounds as you said but again the ground determins which element is illuminated?

[big mike71]

My chevelle did basically the same thing and it was the ground.

[attack eagle]

let's start with the basics of a dual filament bulb

+fil 1 - neg both + fil 2


If you move the ground from the common terminal you could possibly cause this problem as 12+ would go thru both filaments for one circuit.

Break out the Multimeter and figure out which of the pins is common with outer shield of the bulb, and then make sure you have a good ground there.

At that point you are dealing only with figuring out which is the 15w and the 5w filament, and making sure that they are not cross wired/shorting to eachother, then connecting them.

BTW... check the same side rear too.