Weird tail light problem

[hawkeyepoole]

New weirdness with my tail light issue. On Saturday I removed the turn signal switch assembly from the steering column, took it apart and cleaned the contacts with 400 grit sandpaper. I reinstalled it and, voila'! the right turn signal works! However, now the left one doesn't? WTF??? I took it apart again twice and sanded all the contacts, to no avail.

Then I went into another truck at our hangar and stole the turn signal switch off of it. Same result! WTF again?

I'm getting more and more confused. My wiring is obviously OK as the LEFT turn signal on the rear was working before and now the RIGHT turn signal is working.

I'm not sure what to do now, but try swapping parts like maybe the turn signal flasher device itself, next.

Ideas? Comments? (All grounds are perfect at this point, as everything has been polished and cleaned.)

 

[Cleveland Iron]

Rather than using a voltmeter to check things out, build a device that loads the circuit. Easiest one is a couple of test leads and a 24 volt bulb wired together. Quick test for power, quick test for grounding problems. Just depends on where you clamp the leads. ( I suggest an alligator clip on the end you are grounding. )

Past usage of such a test device has provided me with go, no-go, and WTFO readings without having to try to read the meter in sometimes inconvenient locations.

 

[hawkeyepoole]

i have since swapped out the turn signal switch and the problem is the same. I'm going to have to get a voltmeter and a load meter and see what's up. this is very weeeeeiiiiiirrrrdddd......

 

[moving chicane]

I've currently got a similar issue, No Blinky on right rear, but do have 24V on DMM. I picked up a 24V test probe this evening to try to sort it out. My money is on bad ground but we shall see.

 

[dabtl]

Pay attention to Cranetruck. He is the guru of electrical problems. Ask me how I know!!

 

[moving chicane]

I was wrong on my issue. I plugged in the test light and it blinked just fine, so I put the flasher bulb back in, and nothing. I tried another known working bulb and still nothing, so I put the probe back on and again it works.

after cleaning everything up meticulously for the forth time, and getting the same result I decide to work on something else.

So while I'm laying under the dash installing an air alarm light. I randomly feel around, looking for weird things going on (missing hardware, loose or broken wires) I get to the three lever switch and lo-and-behold the retention ring isn't tightened down. So I snug that up and check the turn signals. I am proud to report everything is now working, including my new air warning light.