Brake Light Blink W/ Turn Signals

[AirNWater]

I have a 93 Ranger 3.0L that I have been rebuilding - almost done. Until I noticed that when I turn on a turn signal (either side gives same results), I noticed my tail lights blinking too. Also, the High Brake light on the cab blinks too. A couple of notes: I've replaced all the lights with LED Lamps. I've replaced the Blinker with an LED blinker (that was fun - I had to run jumper wires out of the fuse block to the flasher in order to get the right polarity on the flasher). The truck also has a new adapter for a 4-wire trailer connector.

I've tried replacing the rear turn lights with the normal style lights and get the same results. I've tried removing the adapter for the trailer wiring and get the same results. I've read a couple articles that indicated it might be a grounding issue, so I added extra ground wires (one on the turn signal connector and one on the brake light connector) at the left rear turn signal and still get the same results. The new ground wires run to a new screw I added into a brace just behind the turn light assembly, making sure to sand down to bare metal before making the connection. I've also measured the resistance of the grounds and I'm seeing 0 ohms to the body. Looking at the basic wiring diagrams in a Hayes manual, I'm not seeing a common path for the power to get from the rear turn signals to the high brake light nor the regular brake lights (but they don't show the internal working of the switches, so could be hidden in there somewhere).

Any additional thoughts on where to look or what to try? I'd like to start driving it, but really don't want to be venturing out into traffic with funny tail lights.

 

[94tanner]

Only thing I can think of is maybe the blinker and tail lights share a common type of connector and the connectors are switched somewhere during installation?

Sent from my SM-G925V using Tapatalk

 

[55trucker]

If you remove all of the LED items and return the circuits to what they were will the issue go away?

 

[AirNWater]

No, the issue remains. Doesn't seem to be related to LEDs

 

[Doofy]

Perhaps the flasher you rewired has issues.

 

[AirNWater]

Solution Found

55Trucker, you were on the right track. I thought I had replaced all the LED bulbs, but forgot the new High Cab light was LED as well. Once I disconnected that, everything with the original bulbs started working correctly.

It turns out (and I can't really explain why) that I need to add resistors to the rear brake lights to solve the issue. Once I added 2 resistors in parallel with the rear brake lights all my issues went away. It really doesn't make sense to me since the brake lights and turn lights aren't on the same circuit.

Well, at least now I can start driving it.

Thanks for the suggestions.

 

[55trucker]

You didn't mention if you replaced ALL the turn signal/park lamps with LED's or just the rears.

The replacement LED flasher has to be capable of functioning in a circuit where both types of bulbs are used (if not are all LED'S).

I did not think that in 94 an electronic (solid state) flasher was supplied as an OEM item, thought it was just a thermal-mechanical flasher. That flasher will not function with LED bulbs seeing as there is now little to no load seen by the flasher so it not open/close. An electronic flasher as well needs to *see* a load to function properly, remove the load (one bulb burns out) and the circuit will not flash or it will hyper-flash.

The LED flasher is needed where the LED bulbs are used to overcome this situation. 94 should be a two pin flasher, to the best of my knowledge the flasher is not polarized (a thermal flasher will not be), as for the taillights flashing in my opinion that is the result of (once again) no load on the turn signals, the turn circuit is finding the taillight circuit and using it as a ground path causing them to flash as well.

See this pdf link for info on the LED flasher.....


http://www.tetrix.com/Flasher Primer.pdf

 

[AirNWater]

Steve,

I have replaced all of the bulbs with LED's. I replaced the standard thermal flasher with an LED Flasher specifically because I knew the LEDs would not have enough load to properly activate the thermal style flasher. The LED flasher is polarity sensitive, that's why I had to do a bit of rewiring for the flasher. It is a 2 pin flasher and physically fits where the thermal flasher was. but, the polarity of the connections inside the fuse block were reversed for the LED flasher, so I installed 2 short jumper wires and mounted the LED flasher on the outside of the fuse block.

I thought, the only reason for the load resistors was to be able to use LEDs without using the LED flasher. Since I changed the flasher I assumed I didn't need the resistors. The other strange part of this, in my mind, was that the resistors needed to be connected in series with the brake lights, not the turn lights. When I tried connecting them to the turn lights, I still had the bleed thru and the bake lights flashed. Luckily, I wasn't sure where I needed to connect them, so I just did a temporary connection until I had things working correctly.

It was an interesting experience / learning lesson. For future reference, always add those resistor if changing to LED bulbs!

Thanks again for the exchange of ideas!