Back right turn signal won't work

[kujocku]

The back right turn signal won't work.  Front right bulb glows but does not blink. I removed right rear bulb and it looked fine, replaced bulb anyway but still does not work. Left side working fine. socket looked good Where can I look?  Thanks Neil

[datzenmike]

You should put the year of your truck in your profile. Where are lots of differences between the years.

 

 Turn signals use TWO bulbs on the 620. The chances of both being blown would be beyond rare.  Brake and turn signals share these two bulbs so try the brakes and see if they are not working also.

 

If both RR brakes and turn signals are not working...

Passenger side rear frame rail behind the tail light is a round 6 pin plastic plug connecting the chassis harness to the rear tail light harness. As this is subject to wet, and thrown debris from the tires, it's a natural spot for corrosion. Pull the plug apart and inspect the Light Green/Black wire. Sometimes just unplugging and plugging back together cleans the contacts. (this is the easiest and likeliest thing)

 

If you have a meter, check the Light Green/Black wire for power with brakes on and then with turn signal on. If nothing there then the problem is in the turn signal switch. One of the solder connections has come apart

 

If RR brakes are working but signals are not...

Then obviously the bulbs and the wire are good. The problem will be in the turn signal switch. One of the solder connections has come apart.

 

As both brakes and signals share the same L&R wires and bulbs the turn signal switch must disconnect the brakes and connect the flasher. When the switch returns the brakes are re connected. I've had a wire fall off and it was a simple fix with a soldering iron.

[kujocku]

It is a 77 620 it is has a 2 bulb system for each side of the rear turn signals, and for the right rear turn signal,  the inner bulb works the outer bulb does not.

[datzenmike]

     Well that's way different. Either the black ground wire is broken or off or the power wire. Check to see if the spring under the center contact had stuck in the compressed position and the bulb is not making contact when pushed in.