Weird issue

[bd]

Okay bd, I jumped the flasher terminals and here are the results:

With test light on B- no visible light on either blades.

Was the left turn signal energized with the ignition switched ON during this test?

[JohnnyPopper]

Affirmative sir

[bd]

It sounds like there may be two issues. 

First, if zero turn signal power reaches the bulb, then there is an open in the left turn circuit to the bulb.  Is there any change in power at the bulb contact when you energize the 4-way flashers with the turn signals cancelled?

Second, voltage measured on the turn signal contact when the park lights are on implies either a less-than-perfect ground to the lamp socket or cross-feeding between the turn and park lamp circuits.  Was the park/turn bulb installed when you measured the extraneous voltage on the 'turn signal' contact?

[JohnnyPopper]

It sounds like there may be two issues. 

First, if zero turn signal power reaches the bulb, then there is an open in the left turn circuit to the bulb.  Is there any change in power at the bulb contact when you energize the 4-way flashers with the turn signals cancelled?

Haven't tried that yet, will do.

Second, voltage measured on the turn signal contact when the park lights are on implies either a less-than-perfect ground to the lamp socket or cross-feeding between the turn and park lamp circuits.  Was the park/turn bulb installed when you measured the extraneous voltage on the 'turn signal' contact?

No, the bulb was not installed, measured at the blade of the socket.

[bd]

Bear with me.  Remove the right front park/turn bulb then perform your voltage checks at the left front just as before.  Any differences? 

And, what were the results with the 4-ways energized and turn signals canceled?

[JohnnyPopper]

Sans Bulb, no difference.

Haven't tried the 4-way yet.

[JohnnyPopper]

Well, just tried the 4-way, all four corners work, even the front side marker. 

[bd]

It sounds like there may be two issues. 

First, if zero turn signal power reaches the bulb, then there is an open in the left turn circuit to the bulb...

Second, voltage measured on the turn signal contact when the park lights are on implies either a less-than-perfect ground to the lamp socket...

You may have a compromised turn signal switch.  The front and rear turn signals are isolated through the switch, so there could be a connection problem in the switch that affects only the left front turn and left dash indicator without impacting any of the other lamps.  The four-ways are switched separately.  Since the four-ways work, the wiring to the left front turn lamps is intact.  You can test this by unplugging the turn signal switch at the column and jumping the cab harness plug purple wire to light blue wire with the ignition switched ON.  The left front and left dash indicator should blink with the flasher if there is sufficient lamp load with only those lamps.

I still think you have an imperfect ground to the left front park/turn lamp.

[JohnnyPopper]

Even weirder- Started working again today...

[Shifty]

 

[Chevygold]

I had a similar problem but with one of the rear lights, brake lights and 4 ways but no flasher on one side and it was the indicator switch, fitted a replacement and all good again, the left dash indicator light has never worked guess that is the dash pcb at fault?
Graham

[JohnnyPopper]

Been awhile, (where is the symbol/icon for music?)

So recently, like the past, the left turn signal began working again, i.e. both front and rear.

To refresh, when it acted up, the left turn signal only lit the rear, the front stayed dormant, and the dash indicator did not light. I could hear the flasher clicking due to the rear brake light being active.

Now, the front and rear are flashing, the dash indicator is working, BUT, the left rear brake light does not work.

I guess, to avoid being pulled over, I can turn on my left turn signal when I brake or slow down...

I kind of suspect an earlier observation by bd that my turn signal device may be compromised.

I can't say if in past cycles of working/not working that I noticed the brake light being operational or not. This go-round I notice it when backed up to a reflective surface at night. 

TIA for your help.

[JohnnyPopper]

I wonder if spraying electronic contact cleaner would work?

How hard is it to replace the turn signal dealeo?

I think I have one, just wondering how you get the wire terminal through the steering column. Looks painful...

[bd]

It's actually fairly easy.  You'll need a steering wheel puller and lock plate depressor.  A tilt column adds a few more steps but no additional tools as long as you don't need to disassemble the tilt mechanism.  The T/S switch ribbon cable and connector just slip DOWN through the column.  You need to keep the long axis of the connector parallel to the length of the ribbon cable while feeding the new cable down column.  If you want to take the easy way, tie a pull-string to the connector before pulling the old switch from the column.  The ribbon cable is encased in a semi-rigid flat plastic conduit with a longitudinal slit that slides UP the cable from the connector end once the new cable is in place.  It sounds more complicated than it is.

[JohnnyPopper]

Thanks bd!

I think I have a replacement somewhere, will confirm.

So in theory, I should be able to plug in the replacement to the connector on the lower column, and verify functionality.

If the symptoms persist, I save my self the trouble.

I was looking at the outboard connectors on the side of the step side to the light fixture, wondering if there were ground issues there, or others.