[halftwisted_3]

My headlights seem to turn on whenever they want.I try and turn them on but nothing, they go out for a couple days and then they come back on. Any ideas on what i should be checking? Also i noticed that my license plate lights dont work either..Any feedback is greatly appreciated?

 

[Wrench97]

They turn on even when the switch is off?
Check the switch and harness plug for shorts or burnt wires.

 

[mack1]

This message has been deleted by Midnight Tech. Reason: Forum decided wrench's post was so good, it gave it to us twice.

I can believe that:grin::grin:

 

[Raylo]

Could also be a sticky relay. Not much in the circuit but switch, fuse, relay and some wires....

 

[Wrench97]

No relays on a 68 Chevy. Dimmer switch on the floor after the dash H/L switch.
The headlight switch has a circuit breaker built in, the tail lights are fused before the switch on a separate circuit.

 

[halftwisted_3]

No, whenever i try to turn them on tey either dont go on for a couple days at a time or it simply just works.

 

[halftwisted_3]

No relays on a 68 Chevy. Dimmer switch on the floor after the dash H/L switch.
The headlight switch has a circuit breaker built in, the tail lights are fused before the switch on a separate circuit.

Is there any way that i can test the headlight switch?

 

[Wrench97]

If you pull the switch out and check the connector for signs of burnt wires or melted connector, sometimes the wires will even be loose in the connector. also if it just the headlights check the 3 wires at the dimmer switch one will hot from the headlight switch the other 2 are high and low beam circuits feeding the headlights sometimes it is the dimmer switch that causes the headlights not to work or the connections at the switch.

I'll look around to see if I can find a wire diagram to get you the wire colors.

 

[Wrench97]

Here is a link to one I found from memory it seems to be correct.
Using a test light to back probe the connector at the headlight switch do not pierce the wire insulation just probe the brass contact in the plug.

12 gauge Red should be hot all the time it is the feed for the headlights
16 gauge Dark Green is the feed from the fuse box for the tail lights.
14 gauge Light Blue is the feed to the dimmer switch should be hot when the switch is turned on and feed 12v to the dimmer switch.

Check these and see what you have the red 12v is fed through the bulkhead connector on the same circuit as the ign switch so you should have current there if the truck starts.

http://www.boomspeed.com/bofh1968/chevy/master_wiring_diagram.pdf

 

[SJCharney]

You may want to reach out to this site................www.67-72chevytrucks.com. There is a great tech forum there specifically for chevy trucks.