[Sport69]

All turn signals work when my parking lights & headlights are off, but when I turn them on the front turn signals don't work. The back ones still work, just not the front. The front turn signals don't seem as bright when they are working (parking lights off), as when the parking lights are on. I have all new wiring harnesses, and have replaced both flashers. All other lights, signals, and emergency flashers work. I have read in some other posts about the ground, but I can't believe with everything new that this could be the issue. Suggestions?

[Old Goat 67]

Been doing electronics all my life, sounds like grounds.

Clean off the new paint.

[Goatracer1]

What are they grounded to and does that have a good ground? Remember paint is not a good conductor.

[Old Goat 67]

If you can't use an ohmmeter, run a wire from the neg battery post to the ground screw for a test.

[GT182]

Your front signal lights are grounded to the core support. Make sure there's a ground strap from the passenger side inner wheel well to the frame. Core support is bolted to the fender and fender to the inner wheel well.

[Sport69]

Haven't had a chance to check the grounds, hopefully this weekend. I'm not sure how they are grounded as the body shop installed the front harness after the paint & assembly. I'll check for the ground strap from the inner fenderwell to the frame. Thanks for all of your replies/suggestions, a definite help.

[Sport69]

Ran a ground from the frame to the inner fender well, no difference. Ran a ground from the battery negative to the turn signal housing, no difference. Other suggestions???

[LATECH]

Had the same problem with cousins car when I installed the new harness for him.
Turned out that Hop sing had the wires switched in the plug for the front running/turn bulb.
Had to cut and splice a new harness as they were molded plug ends (arrrgh) but it worked Fine when done.
Be sure it isn't a problem with the side markers as some were wired different. IIRC 68 did not have side markers??? maybe I am wrong, but the ones that have side markers are wired different so the turn signal alternates from the the front to the side bulbs when flashing. I am sure you have seen that before.
Check the diagram and then ohm the wiring between the two connector (front and sides) to be sure it is configured correctly. Go from there.
Like I said , cuzz and I had the same trouble.It was a manufacturing mistake as far as I can tell.
IIRC he got a harness from classic industries.

[Sport69]

When I stated that the fronts worked when the parking/headlights were off I didn't notice that the side-marker lights do not blink at any point, with the parking lights on, or off. Would this indicate that Latech may be on to something. Seems like maybe I should be checking the wiring, especially to the side-markers.

[LATECH]

That is where I had trouble on the 69 my cousin had.
I installed the 4 piece harness for the entire car, and the turn signals on the front were wired wrong....brand new harness.

The only other place we had an issue besides the front turn signals, was the ignition feed for the distributor.The harness he had , came with the resistor wire and the spade end for the coil.I surgically removed that and installed the big heavy red wire for the HEI he has in it. The 69 did not have HEI . That wasn't available until 74 I think.
The 2 power wires to the front bulb were reversed.I just snipped them and swapped sides and voila...

Best of luck to you.

[TedRamAirII]

Well you didnt say what car you had, but since you said "side markers" lets ASSUME its after 68. I see where one poster asked about side markers. All cars had side markers in 1968, Federal law mandated it, and they should not blink. Grounds are always an issue with old cars. Sometimes the socket has its own ground wire, sometimes it has a contact on the edge to connect when its mounted in the housing (if the housing is metal and its electrically bonded to the body) . Be sure it has all the correct bulbs in the correct sockets and they are making good contact. I think they should all be 1157 bulbs. Put your hazards on and do your checking. The turn signals and brake lights all go through the turn signal switch. If its been sitting a while, work the lever 20 or 30 times to try to get the contacts clean. You will find it.

[Sport69]

Ted,
It's a 69 F-bird. Front side-marker lights are suppose to stagger-blink, opposite the front turn signals. All of the bulbs are correct, and I even replaced new ones with other new ones and still have the same issue. Like I said, i'm starting to believe LATECH is onto something with the new harness wiring possibly having some switched wires.

[TedRamAirII]

Originally Posted by Sport69

Ted,
It's a 69 F-bird. Front side-marker lights are suppose to stagger-blink, opposite the front turn signals. All of the bulbs are correct, and I even replaced new ones with other new ones and still have the same issue. Like I said, i'm starting to believe LATECH is onto something with the new harness wiring possibly having some switched wires.

I did not know that. I would be getting a wiring diagram and start checking at the front turn signals.

[rexs73gto]

If your lamps are going dim when you trun on your lights then the wiring is looking for a good ground. I think if you check ALL your grounds & make sure you don't have any paint or rust or whatever blocking the rounds you 'll have your turn signals back working in no time. If you have to on your grounds scrape ALL the paint off on the ody where your grounds are that alone will cure your concern.

[1974gto]

I had a similar issue with my 74 GTO, all new harnesses and my blinkers would not work when i turned on the headlights. Thought it was a ground issue. Turned out to be one of my rear tail light bulbs was incorrect. Sounds stupid but that is what it was. Kicked myself in the a$$$

[Sport69]

rexs,
The only lamps that are "dim" are the front turn signals. when I turn them on, without the parking/headlights, they blink, but I can tell they're dimmer than they should be. The side-marker lights never blink at all. When I turn on the parking/headlights the parking lights and sid-markers are nice and bright, but they never blink at all when I put the turn signal on, but the rear works perfectly? I will go back and double-check the grounds again, but if I ran a wire directly from the battery negative to the turn signal housing, like oldgoat67 said, wouldn't that remove the ground as the problem?

1974gto,
Did your rear turn signals work before you discovered the wrong bulb? Mine work perfectly in the rear, no matter what's on or off.

[Pepi]

Parking lights are not bright if they double as blinkers also. You said all of the bulbs are correct, but are they installed correctly. I have seen people able to put them in backwards so the parking lights are bright, and turn signals are dim.

[1974gto]

Originally Posted by Sport69

rexs,
The only lamps that are "dim" are the front turn signals. when I turn them on, without the parking/headlights, they blink, but I can tell they're dimmer than they should be. The side-marker lights never blink at all. When I turn on the parking/headlights the parking lights and sid-markers are nice and bright, but they never blink at all when I put the turn signal on, but the rear works perfectly? I will go back and double-check the grounds again, but if I ran a wire directly from the battery negative to the turn signal housing, like oldgoat67 said, wouldn't that remove the ground as the problem?

1974gto,
Did your rear turn signals work before you discovered the wrong bulb? Mine work perfectly in the rear, no matter what's on or off.

Mine would not blink if headlights were on.

[LATECH]

Originally Posted by Pepi

Parking lights are not bright if they double as blinkers also. You said all of the bulbs are correct, but are they installed correctly. I have seen people able to put them in backwards so the parking lights are bright, and turn signals are dim.

Pepi:
That is what his(and my cousins ) were doing with bulbs installed correctly.( Parking was bright, and turns were dim and you couldn't see the turns hardly at all)
I installed a Brand new classic industries harness, for the entire car
I found the 2 leads were reversed on the front bulbs when the new harness was made.

An easy check would be to grind off the 2 bayonets on a known good bulb ( as they are offset for polarity) and push it in the socket with the circuits on: parking lamps on and turn signal on as well. Then put the bulb in backwards and see if it all works correctly.That would be any easy way to verify the condition without cutting any wires
Be sure to position the bulb correctly where the soldered tips touch the contacts in the socket or everything will light up.

[Sport69]

I contacted a rep from American Autowire, who makes the harnesses for Classic, and he said that since my parking light assembly was aftermarket (somehow it should be a four-letter word) that they tend to over-plate the housing and it doesn't make a good ground. He said that sometimes you have to actually solder a ground to where the bulb contacts the housing and ground it directly. That could expalin why I couldn't get ground it directly from the battery to the housing screw.