08-04-13, 01:58 AM
I went to turn on the headlights and nothing, they all worked fine the day before.
I checked the dimmer switch and there is no power going to it.
I need to know the next troubleshooting step.
Should I jack the car up and check the fuse able links, or Check for power to and from the headlight switch. Which one first?
08-04-13, 08:49 AM
You will have to check the switch. It is designed as a fuse and can fail.
08-04-13, 02:44 PM
I also forgot to mention that the running lights are still working. Could the headlight switch work for the running lights and not the headlights?
Check the dimmer switch on the floor for a broken wire or being unplugged. Power goes to the dimmer switch before going to the headlight switch. That would account for the running lights to be working and no headlights.
08-05-13, 11:31 AM
Is it all headlights, low and high beam or ??
Could be loose connection- check and secure at dimmer switch, guidematic relay, headlamp switch and grounds
Malfunctioning dimmer switch- chk voltage at dimmer switch w test light if lights only at lt blue wire replace.
Open wiring- light switch to dimmer switch- chk voltage at dimmer w test bulb, if lights on at headlamp switch lt blue wire but not at dimmer
switch, repair open in yellow wire. (Off my 80 service maunal, 77 service manual states lt blue wire)
Circuit shorted to ground- if after few mins of operation, headlights cycle on or off and or a clicking noise can be heard from headlamp switch
(circuit breaker opening and closing) repair short to ground in circuit between headlamp switch, dimmer switch and headlights.
After repair, check headlight flickering after one min operation. If flickering occurs, circuit breaker has been damaged and headlamp switch
must be replaced.
Malfunctioning light switch- chk voltage at headlamp switch yellow and blue wire w test light. If lights at yellow but not lt blue, replace light switch
Most likely the fusible links. They loose their insulation and melt against the engine as the car ages. Ask me how I learned this.
08-05-13, 11:04 PM
Thanks everyone! I found the culprit, it was a burned up connector going up from the dimmer switch. The terminals on the dimmer switch itself looks corroded, and probably caused it. I'll just bypass the connector, and buy a new dimmer switch.
I appreciate all of the help.
08-05-13, 11:44 PM
New dimmer switch? Good luck on that.
08-06-13, 12:03 AM
It shows they have them in stock at O'reillys for $9.99
BWD - Headlight Dimmer Switch
Part # DS111
08-06-13, 10:18 AM
There was a change in dimmer switch application sometime in the 77- 79 production. I think it was after 1977. The original switch set the primary lights on high beam along with the secondaries . The later switch just turner on the secondaries.
08-06-13, 10:51 PM
Thanks for the info!
I guess I'll just try to clean up the terminals on my old switch.
Glad it turned out to be a simple fix, Tom.