Should be able to multimeter the rear harness to test.

Are you sure that your electronic flasher is good? I would think that with the electronic flasher your fronts should work even if rear harness is disconnected.

 

Okay, update with a little bit of good news.

Both sides flash, but only if the parking lights are off.

I put the old bulbs back in the front marker sockets. The driver's side signals flash, but slow, and the front marker bulb doesn't completely go out. The passenger side signals flash normal speed, same as the hazard speed.

When the signal switch is on, the marker and front signal both blink in unison and the proper side interior indicator also blinks with the front and rear lights.

Now...if I turn the parking lights on, the signals AND the hazards don't work. Also, with the parking lights on, the filaments in the front marker lights are so dim the filament is barely even orange.

This would tell me the brown wire, which is the ground for the signals...work, but the signal wires do not act as a good ground when the park lights are switched on.

Anyone concur?

 

Also, with the old bulbs back in the front marker sockets, the interior indicators both light back up when the headlights are on. They light at both positions, parking and headlights.

All the exterior lights light as they are supposed to, but the front marker bulbs are VERY dim...very very dim.

 

Okay, another odd symptom. I plugged the headlight warning buzzer box back into the fuse panel. Now, with the old bulbs in the front marker sockets, when I turn on JUST the hazards, the headlight warning buzzer buzzes in unison with the exterior lights, as they flash.

So, some signal wire somewhere is bleeding into the parking lights circuit...right?

 

The difficulty with the light circuits is that some of the operations are fed by two separate circuits. You may find it necessary to go back to the original set-up, then make your changes one after the other, checking the system as you proceed. A portion of the system is as follows:

1. - Headlight - power to light switch is hot at all times. Powered through the dimmer switch gives low or high beam operation, plus dash indication for high beam.

2. - Back-up lights - power from fuse panel - 20 A (DIR SIG BK UP) hot through ignition switch activated by reverse switch and ground to rear crossmember.

3. - Turn Signals - power from fuse panel - 20 A (DIR SIG BK UP) hot through ignition switch to the flasher to turn signal switch to the individual bulbs.

- turn signal off - should have no power out of the flasher.

- turn signal - right - (with parking lights on ) applies voltage from flasher to signal lights and switches 12 v to both sides of the marker light extinguishing the marker light.

- turn signal - right - (parking light off) applies voltage from flasher to signal lights and because marker light is not powered by the parking light selection it now gets power as the flasher operates and the marker light will flash as does the turn signal.

You really need the electrical schematic to troubleshoot. For example the turn signal switch receives power from two sources. (DIR SIG BK UP)fuse and (STOP/HAZ) fuse through the emergency flasher or the brake switch.

Again if your emergency flasher is selected on with parking lights switched on, the marker lights are powered on both sides which extinguishes them. If the emergency flasher is selected on with parking lights turned off, then the marker lights will flash with the signal lights.

By switching to LED and an electronic flasher you may have some difficulty in setting this up, as the original system used a flasher with an element inside to make and break the circuit depending on the combination of resistance created by the bulb filaments. You may have to re-engineer or bypass the marker light set-up that you currently have, so that it is not powered by two sources.


Did you get the schematics from previously supplied link?

 

Yes I did. Thanks for taking the time to write all that out. I think I have ruled out the signal switch itself, as well as the fuses, and IGN switch.

Something to consider...my reverse lights are not connected so that's a bare wire, same as the license plate bulb...it's just a bare wire right now.

Would either of those two make a difference?

 

Reverse lights are a separate circuit, no effect. License plate, minimal impact do to bulb filament resistance with parking lights selected on.