Park lights, but no tail lights??

[maynardogle]

All of a sudden, both tail lights quit working. Brake lights and front park lights are working fine. I am guessing there is a factory connection somewhere that provides power from the #40 circuit to sends +12 to the front harness for the park lights and to the back harness that runs along the frame rail to the taillights. Can anybody tell me where this splice is ?

[dmjlambert]

Check fuses first, then check light bulbs (even if 2 go out at one time). Then check other things. There is a ribbon cable of 4 wires that goes from the cab firewall above the transmission hump, underneath the truck along the frame to the rear of the truck. See if that is in good shape and use a multimeter or lighted tester probe to check for voltages. Many trucks have mangled wiring at the rear of the truck where the previous owner tried to connect a flat 4 trailer connector, so check out that wiring. Here is a wiring diagram: http://67-72chevytrucks.com/vboard/s...27#post9186727

[dmjlambert]

And I believe there is not really a wire splice that joins front park lighting to tail lights. I could be mistaken but I think the front park light and tail light wires get power from individual brown wires that go to the headlight switch connector.

[Sheepdip]

Check Grounding Also.

[Ironangel]

Originally Posted by Sheepdip

Check Grounding Also.

This! While your checking that ribbon alo0ng the frame for continuity, make sure the bed is grounded to the frame. The frame should be grounded to the motor, and motor to the negative terminal on the battery.

[72c20customcamper]

Don’t think a ground is the problem . If the turn signals and brake lights work it’s grounding a bad ground in my experience will cause the turn indicator to glow as it backfeeds searching for ground . Could be a bad headlamp switch? Or just a pinched or broken wire like said check the bulbs first one may have gone out before the other and wasn’t noticed .

[kwmech]

Do the dash lights work, they are on the same fuse circuit

[67C10Step]

Good advice here. Check fuse first, Then I'd go to the connection at the firewall where it exits the cab. If you have no power there my guess would be headlight switch.