Front Turn Signals/Running Lights don’t work with LEDs - Electronics experts? (1 Viewer)

[Rocky_LC]

This is a 1974 FJ40, with the front running lights and turn signals in an extended pod above the fenders.

I had LED lights, front and rear. Now they are only LEDs in the rear.

In the front, there is a socket that accepts the dual filament bulb (1157 IIRC), one filament for running lights, and one filament for turn signals.

The sockets are clean, and I ran a separate ground to the chassis frame. So I’m certain the grounds are good and the connections are good.

I have a flasher unit compatible with LEDs installed.

If I put the “dual input 1157 LED” bulbs in, I can only get the running lights to operate. If I disconnect the feed to the running lights, then the turn signals will work!

If I put in incandescent bulbs, both running lights and turn signals will operate, separately and simultaneously.

Anyone have a theory on what’s going on?

Right now I’m just running old incandescent bulbs up front. I would like to run the 1157 LEDs because of the lower current draw, less heat in the housings, and brighter light.

Maybe it’s just the crappy Chinese LEDs that I bought, and I should try a more expensive set.

Rocky

 

[B y r o n]

Have you tried to apply power at each contact to see if both work? You may have bad bulbs.

 

[1969FJ]

Buy an LED conversion kit.

 

[45Dougal]

My guess is that you have a little resistance in your ground line despite your attempts.
When you switch on the running lights, the turn signal filament is reverse biased because the running lights are at full 12v, while your led compatible turn signal unit probably puts out a lower voltage.
Check your ground again, or add some small resistance upstream for the running light? Like a 5w bulb for example as a test

 

[Rocky_LC]

That makes sense, 45Dougal. I’ll give that a shot. My guess is new LED bulbs wouldn’t work either!

I did check both LED bulbs - it’s easy to fire up both sides with a quick application of a 9V battery to the terminal and socket base.

Rocky

 

[pb4ugo]

I think it's possibly a ground too. Did you attach a wire to the fixture the socket is attached to, then grd to the frame?

 

[B y r o n]

LED bulbs generally are different than standard bulbs. They will only light if power is applied to the correct lead and will not light if power/voltage is applied to both leads. I'd double check your sockets to ensure there is no possibility that power is transferring from the ground to any of the contacts.

 

[Rocky_LC]

I think it's possibly a ground too. Did you attach a wire to the fixture the socket is attached to, then grd to the frame?

I did that on the passenger side, ran the wire through the drilled out stud (with the other two wires in the harness), and grounded to the chassis.

I’ll try that next on the drivers side…

 

[Rocky_LC]

LED bulbs generally are different than standard bulbs. They will only light if power is applied to the correct lead and will not light if power/voltage is applied to both leads. I'd double check your sockets to ensure there is no possibility that power is transferring from the ground to any of the contacts.

Not sure if I checked that…. I’ll try that next!

 

[Rocky_LC]

So I’m pretty sure Dougal was on the right track…

I measured 0.150 VDC between the light reflector and the battery (-) on the passenger side that I had installed my new separate ground wire, and 0.750 VDC on the driver side.

I then ran a separate ground wire on the driver side, and got the voltage drop from the socket to battery (-) down to 0.050 VDC.

My LED bulbs still don’t work when installed in the sockets, though. Incandescent work fine.

I think it had something to do with the “dual function” (1157) LED bulbs & wiring. I have no issue with the “single function” LEDs in the rear tail lights, but each bulb is in a separate socket/circuit….

Thanks for the help and suggestions so far!

Rocky

I’m wondering if the source voltage for the flashers is less than that for the running lights, but that still doesn’t explain why nothing works when even one LED bulb is installed…

I’ll check that when my new LED bulbs arrive…

 

[peesalot]

Have you tried switching the bulb leads, meaning switch fillaments if that makes sense, use the running light power that you say works fine and put it on the " blinker" and hook the flashed blinker power to the one you currently are using for running lamp, maybe ?

 

[45Dougal]

Ah, that's interesting. If the flashers stop working when only one front LED bulb is fitted (and the side lights turned on), then that points to it being a feature of the flasher unit.

It's probably sensing some voltage from the side lights and shutting down.

Try adding a diode (e.g. 1n4001 - if you have such a think kicking around) in the turn signal line (pointing towards the LED).

That should stop anything back-feeding to the flasher unit.
Otherwise yea, wait for the new bulbs

 

[Rocky_LC]

It might be a good test to see how things work with a non-LED flasher…

If I get the “rapid-flash”, at least I have verified the wiring is good..

This is interesting, but frustrating too…

I’ve got a diode or two around…. Don’t really want to splice into my wiring, but…

It’s also a good idea to flip-flop the wires, and see if anything changes.

Thanks for the ideas!

 

[charliemeyer007]

I have taken bulbs (usually dead) apart and made them into test leads so that you can jumper them in any configuration you want but they will not damage your original socket.

 

[Rocky_LC]

Another excellent idea!

I just may have one of those burned out 1157 bulbs!

 

[Rocky_LC]

Got my new (different) “dual color” LEDs…

Again, some wierd symptoms, and I’m still evaluating…

1) With the “running lights” on, the turn signals flash works. Like a previous poster noted, only one of the “filaments” works at a time, so the running light shuts off while the flashers flash.

(This is OK, because the lights are different colors, and there is just a split second sa the bulb transitions between one color and the other).

2) When the parking lights are OFF… The right bulb has kind of a weak/wimpy flash…

It’s crazy how sensitive to minor differences these LEDs are. These differences seem like they have no effect on incandescent bulbs…

Rocky

 

[Rocky_LC]

FIXED THEM!

Just took more cleaning up of the bullet connections in the passenger side harness.

So basically I cleaned up (and applied contact enhancer - Kopper-Kote) on every connector on the harness past the firewall, cleaned up the socket connections, and ran separate (new) ground lines from the reflectors to the chassis.

It would have been a lot faster had I just done everything at once instead of piecemealing it!

Rocky

 

[B y r o n]

Glad you got things working!

 

[Rocky_LC]

Me too! Thanks!

 

[ECBMCC]

Rocky, congrats on figuring it out. I have a 1977, so the dual light setup on each fender parking and turn signal. Any idea what LED bulb I’d need to replace both bulbs? I’m concerned with the hyper linking but it didn’t appear you had that issue. The Auxito bulbs supposedly don’t hyper blink, supposedly. Anyway happy for you.