Why would both turn signals blink?

[chuckyb]

Hi all, yet another turn signal dilemma...

Upon installation of Centech harness and manual rebuilt steering column with replacement TS switch. Either left or right turn signal from the lever results in both front turn signals blinking.

I have swapped in my old turn signal switch but get the same results.

I have new correct bulbs in my old cleaned up turn signal buckets. I have verified that I am using the bright filament for the blinker and the weak filament for the park lights.

I have solid grounds from the headlights and TS buckets to the core support. Headlight and TS ground are attached to same threaded post on the driver and passenger side.

Hazards, headlights, tail lights all working great.

No obvious signs of exposed chafed wires touching but I suppose it’s possible somewhere.

Any ideas appreciated!

 

[Broncobowsher]

Do the dash indicators come on?
Hazard switch, is it on?
Do the rear brake lights work correctly? In turn as well?
Are you running regular bulbs or LED?

 

[Nothing Special]

Every time I've resolved a weird automotive electrical situation it's ended up being bad grounds. So I'd start with trying to improve the ground connections at all of the lights.

 

[roundhouse]

Are both rear lights blinking
Or just the fronts ?

Try removing one of the front bulbs

Might have an issue with the new harness somehow

 

[chuckyb]

Do the dash indicators come on?


Yes, I get double dash indicators just like when the hazards are on.

Hazard switch, is it on?

Nope, hazards work and switch on and off just fine.
Do the rear brake lights work correctly? In turn as well?

Rear lights work fine. One blinker at a time and works fine with headlights on and braking too.

Are you running regular bulbs or LED?

All new regular bulbs from NAPA.

 

[chuckyb]

Every time I've resolved a weird automotive electrical situation it's ended up being bad grounds. So I'd start with trying to improve the ground connections at all of the lights.

I think my front grounds are good. I’ve got threaded posts into the core support. I did add another jumper wire ground and still have the same issue.

 

[chuckyb]

Are both rear lights blinking
Or just the fronts ?

Try removing one of the front bulbs



Might have an issue with the new harness somehow

The rears blink one at a time like they should. I’ll try removing a bulb.

 

[DirtDonk]

You can check for voltage on the front turn signal wires coming out of the column. If both have power then the fault is in the column.
I can't think of anywhere else that would be easy to short out on each other either, but since you said it does it with both old and new switches, it's likely something at the connector.

A wire worn bare inside the column could do it, but unlikely that both switches have the same issue. But check them visually anyway (one is out and easy to check) just to be sure.

Unless there is some other point in the new harness where the two wires come close to each other, that's the only area I can think of.
Do they both go out on one branch of the harness, or separate just out of the column? Seems to me that one goes to the driver's side firewall and the other to the passenger side, so they must split somewhere fairly close to the column. After that point there is no way for them to cross-talk, so to speak.

I heard that Centech made some recent changes to the turn-signal and hazard circuits, regarding how they connect for the different years and whether your hazard switch is in the dash or on the column. Maybe there is something in that bundle that could do it?
What did you do with the extra wires under the dash (near the brake switch I think?) that are not needed?

Paul

 

[gr8scott]

Do they both go out on one branch of the harness, or separate just out of the column?
Paul

If they still use the GM style turn signal switch connector they go out on one branch then separate somewhere further up the harness. Here's a pic of mine.

 

[chuckyb]

Thanks Scott and Paul and everyone else. The wires definitely branch out and go out the driver and passenger firewall. I will look for voltage downstream of the TS wires and see what I can find out.

 

[jwats73bronco]

I fought turn signal issues on a Centech harness while trying to upgrade to LED turn signals.
Problems turned out to be turn signal switch. Guys at TBP were very helpful plus this board.
But in the end everything had power and a new turn signal switch solved all my problems?

 

[chuckyb]

I wanted to circle back on this in case anyone has the same problem with both turn signals blinking up front. I spent a couple of weeks troubleshooting different turn signal switches. One call to Centech and Jim has me straightened out in a couple of minutes. He suspected I had something wrong with my hazard switch even though I told him my hazards were working correctly. Once I disconnected the hazard switch on the dash, the turn signals worked perfectly.

 

[Sc300insc]

I have the same problem. I just installed new turn signal switch with centech harness. Old switch went bad. Hazard and lights work. But when I use turn signal. Both front markers flash and both turn indicators flash on dash but back lights work correctly. Removed a front bulb and then turn signals seem to work correctly on dash and front.

 

[DirtDonk]

Did you get your issue figured out yet?
Checked grounds at both front turn signals maybe? Try the hazards and turn signals at the same time to see if they act as normal?
Not sure which direction to go yet (other than it might be a bad turn signal switch) but it's a start.

By the way, is this a '74 or later Bronco? With the hazard switch integral to the turn signal switch?

Paul

 

[bax]

Both blinkers will operate as a warning when the fluid level is getting low.

 

[DirtDonk]

Would that be the case for blinker fluid only? Or does it work with all fluids, including transfer case and differentials?

 

[bax]

Would that be the case for blinker fluid only? Or does it work with all fluids, including transfer case and differentials?

Yes blinker fluid only. Transfer cases and diffs only whine.

 

[jerry]

All kidding aside, I had the same thing happened to me with the stock wiring harness on my '70. I replaced the turn signal switch because it wasn't canceling, and that did not repair the problem.

Purchasing an NOS switch off eBay did the trick. Tearing down the old switch, I expected to see something shorting, pitting of terminals, etc. but there was nothing that jumped out at me. But clearly something was wrong.

At tached are a couple of photos of the box, including the part number. Hope this helps somebody else. (I do know this part is also readily available through a number of the Bronco parts vendors.

 

[abn373]

Looks like the dash mounted hazard switch is my issue for the turn signals. I just pulled mine out (and the casing broke as I disconnected it from the Centech harness) and with the hazard switch removed, my turn signals now function correctly up front AND the indicators on the dash function as well. New hazard switch ordered. Its a shame I didn't discover that was the issue before replacing 3 sets of flash modules, 2 column turn signal switches/harnesses and didn't drive my Bronco all spring and summer because of this stupid issue

 

[jerry]

Don't beat yourself up too much, we've all been there. And those that say they haven't are full of it.

Looks like the dash mounted hazard switch is my issue for the turn signals. I just pulled mine out (and the casing broke as I disconnected it from the Centech harness) and with the hazard switch removed, my turn signals now function correctly up front AND the indicators on the dash function as well. New hazard switch ordered. Its a shame I didn't discover that was the issue before replacing 3 sets of flash modules, 2 column turn signal switches/harnesses and didn't drive my Bronco all spring and summer because of this stupid issue