Parking Lights

[Minkota]

I have several older cars / trucks and they all have the front parking lights turn off when the headlights turn on.

I was just curious why older vehicles front parking lights turn off when the headlights turn on.

I ordered a new headlight switch today from GMC Paul and noticed I was able to buy the older switch (67-68) that would turn them off or the newer (68-729 that leaves them on.

[Southcity]

Originally Posted by Minkota

I have several older cars / trucks and they all have the front parking lights turn off when the headlights turn on.

I was just curious why older vehicles front parking lights turn off when the headlights turn on.

I ordered a new headlight switch today from GMC Paul and noticed I was able to buy the older switch (67-68) that would turn them off or the newer (68-729 that leaves them on.

You mention you have several older cars/trucks but you do not mention what years they are. I'm sure one of the other board members with more knowledge on this can chime in but I believe in 1968 the federal safety laws changed which required sidemarkers/front running lights to be on with the headlights. So prior to 68, some vehicles had park lights/headlights on at the same time, some did not.

[Minkota]

Originally Posted by Southcity

You mention you have several older cars/trucks but you do not mention what years they are. I'm sure one of the other board members with more knowledge on this can chime in but I believe in 1968 the federal safety laws changed which required sidemarkers/front running lights to be on with the headlights. So prior to 68, some vehicles had park lights/headlights on at the same time, some did not.

They range from 1946 to 1970 and are not just General Motors. I was aware of the Federal law in 1968. I was just curious if anyone knew if there was a reason for it.

[Katrina/10]

I'd say they were for parking, not driving. I rewired the park lamps in my 51 to be on with the headlights, they were so dim you couldn't see them with the headlights on. So I put them back the way they were.

[Stocker]

Originally Posted by Katrina/10

I'd say they were for parking, not driving.

I agree. That was long before DRLs.

If that's not the right answer, we're both wrong.

[Minkota]

so I finally had a little time to start checking the wiring to try and get my rear parking and brake lights working. I can not seem to locate the harness connectors that are shown on the diagram. where would they typically be located. I did find the three connectors at the rear, but nothing intermediate between the rearmost connector and the firewall junction box.

[BigBird05]

Going from front to back the first connector is inside the cab at the firewall (round), the next connector is in the rear cross member, left side (also round) from there you have individual connectors on the left and right and center for the light bulbs.

[Andy4639]

Originally Posted by Minkota

so I finally had a little time to start checking the wiring to try and get my rear parking and brake lights working. I can not seem to locate the harness connectors that are shown on the diagram. where would they typically be located. I did find the three connectors at the rear, but nothing intermediate between the rearmost connector and the firewall junction box.

Disconnect the rear connector and put a test light in each terminal and go through the signals and brakes and lights to see if you get anything on each wire. The brakes and turn signals are the same wires. The schematic is color coded for all the light for both sides.

Drivers side lights:

Brown: is parking, tail lights, side marker and tag light.
Light Green: is drivers side backup light.
Yellow: Drivers side brake & turn signal

Passenger side lights:

Brown: is parking, tail lights, side marker and tag light.
Light Green: is passenger side backup light.
Dark Green: Passenger side brake & turn signal

[Minkota]

Originally Posted by Andy4639

Disconnect the rear connector and put a test light in each terminal and go through the signals and brakes and lights to see if you get anything on each wire. The brakes and turn signals are the same wires. The schematic is color coded for all the light for both sides.

Drivers side lights:

Brown: is parking, tail lights, side marker and tag light.
Light Green: is drivers side backup light.
Yellow: Drivers side brake & turn signal

Passenger side lights:

Brown: is parking, tail lights, side marker and tag light.
Light Green: is passenger side backup light.
Dark Green: Passenger side brake & turn signal

Awesome, thanks. I probably will not get back on it til the weekend again but I an sure going to try to look at it sooner if I can get away.

[Minkota]

The problem ended up being a combination of a bad turn signal switch and very poor grounds at the rear light fixtures themselves. I added a 10ga wire from the Light Fixtures to the frame and they work great now. Thanks for everyone's help.