Stumped. My 66' Chevelle is exibiting a strange electrical problem. If I turn the headlights on, the marker lights on my front bumper stop working . . . no markers, no turn signals. With the light switch in the 'marker light' position the marker lights and turn signals work fine. The car is an all original . . . and wiring is complete, and uncut, but it is 40 yrs old. Is this maybe a ground problem . . . how do I fix? Or a problem in the switch. I wanted to rule out the switch because the taillights work as expected regardless of headlights. Appreciate the help!

Are you calling the parking lights "marker lights"
The parkng lights are only supposed to operate when the light switch is pulled out to the first click "PARK" position, the taillights also operate along with them.

As for the turn signals, sounds like you have some bad grounds.
Pretty easy to check with a piece of scrap wire, touching one end to the bulb base and the other end to a known good ground.

Your turn signals should obviously work all the time no matter if the lights are on or off. However, the parking lights turn off when the headlights get turned on on the 66 model. Thats the way they were supposed to work back then. That was changed a few years later and im not sure when.

Here is a fix if you want them on all the time.


> Starting in 1968, when side-marker lights were
> introduced, the parking lights remained on when the
> headlights were switched on. Prior to that model year,
> the parking lights switched off when the headlights
> were switched on. I believe this pertains to all GM
> vehicles.
>This is an easy way to
> change this without adding anything or cutting any
> wiring (and its completely reversible). The hardest
> part, especially on a 66-67 Chevelle (with A/C yet),
> is removing the light switch from the dash.
>
> Play it safe, and disconnect the battery first. Then
> disconnect the light switch from the dash, and drop it
> down below the edge of the dash. Before you unplug the
> wiring harness from the switch, look at the position
> of the purple wire in the connector. It will be in a
> slot which is at the end of the switch, farthest from
> the dash. Look for an open slot in the conector which
> is at the other end of the connector, towards the
> dash. Remove the connector from the light switch, and
> then release the terminal of the purple wire from the
> connector using a small screwdriver (you do this from
> the light switch side of the connector). Insert the
> terminal of the purple wire into the open slot of the
> connector which you identified earlier (the one closer
> to the dash). Then just reconnect the wiring harness
> to the light switch, and reinstall the light switch
> into the dash, and reconnect the battery. Now the
> parking lights will function as before in the halfway
> position, but remain on when the headlights are
> switched on.
>
>
>
> Rocky
>
>
>
>

Rocky:

Thanks for the 'How To' !!! Very, very helpful. Now I need to get the switch out of my 66' with A/C . . .

Go, Go, Gadget Gummy Fingers!!! That would help anyway!!

Thanks again. I like the idea of the lights being on all the time!!

Wow Rocky. I didnt even know a mod like that could be made without changing anything. Cool.

Yes, one of the few things you don't need to cut, splice weld or tape to make happen. Just a little labor and voilą, you have modern style running lights.



Rocky