[dmjlambert]

I used to have a thread bookmarked that talked about connecting jumper wires at the turn signal switch half moon connector under the dash, but I have not been able to find it again. Here is the routine from notes I took:

Disconnect the turn signal switch at the half moon connector under the dash. It takes finesse to disconnect it, there are tabs that you can try not to break off. Once disconnected, on the truck wiring side of the connector, connect an alligator clip jumper wire to the terminal fed by the purple wire. That is the wire that comes from the flasher. Connect the other side of the jumper wire to the terminal fed by these colors, one at a time, to make these various lights flash. This tests your truck wiring to the lights:
light blue - left front turn signal
dark blue - right front turn signal
yellow - left rear turn signal/brake light
green - right rear turn signal/brake light

If the lights come on and flash when you give each a trial like this, but some don't work when the turn signal switch is connected and you move the lever, then that would indicate the turn signal switch is broken.

Here are all the notes about that connector:
purple - from flasher
light blue - left front turn signal
dark blue - right front turn signal
yellow - left rear turn signal/brake light
green - right rear turn signal/brake light
brown - from hazard flasher
white - from brake pedal
black - horn button