1984 K20 Problems with Dash Lights

[Phatsalmon]

When I turn on the lights in the Truck, both the turn signal indicators come on. When I turn the dimmer switch the turn indicators dim and brigthen. The external signals are not affected. I have replaced the headlight switch but it did not resolve the problem. Any advice out there?

 

[readymix]

I bet that one or more of your turn signal lights has a broken ground in the socket. This causes the second filiment to act as the ground path.
Are you turn signal bulbs and parking ligkts actimg correctly when the head lights are on?

 

[Phatsalmon]

All external lights are working fine. I can remove all the bulbs and see if this resolves the problem.

 

[readymix]

That might help narrow it down but if the socket was at fault like I mentioned it should cause a wierd indication from the bulbs.