The rear running lights not working?

If the rear running lights on your 1997 Chevrolet 1500 are not working despite the blinkers, reverse lights, and brake lights functioning correctly, there are a few potential causes to consider:

Bulb or Socket Issues: Even though the brake lights and blinkers are working, it's still worth checking the bulbs and sockets for the rear running lights. A faulty bulb or a corroded socket could prevent the running lights from illuminating. Inspect the bulbs and sockets for any signs of damage or corrosion, and replace them if necessary.

Wiring or Grounding Problems: There may be a wiring issue or a problem with the grounding of the rear running lights. Check the wiring connections at the lights themselves, as well as along the wiring harness. Look for any loose, damaged, or disconnected wires. Additionally, inspect the grounding points for the rear lights and ensure they have a solid connection to the vehicle's chassis.

Dimmer Switch: The running lights may be controlled by the dimmer switch on the headlight switch assembly. Even though you've replaced the switch, it's possible that there could still be an issue with the dimmer switch specifically. Consider inspecting the dimmer switch and verifying its functionality.

Body Control Module (BCM): The BCM is responsible for controlling various electrical functions in the vehicle, including lighting. If there's a malfunction in the BCM or a related module, it could affect the operation of the rear running lights. It may be necessary to have the BCM system scanned for any stored trouble codes and further diagnose any BCM-related issues.

Since you've already checked fuses, relays, and the power to the light switch, it's advisable to consult a professional mechanic or an automotive electrician who can perform a more in-depth diagnosis. They will have the necessary tools and expertise to trace the electrical circuit, identify any faults, and resolve the issue with the rear running lights on your 1997 Chevrolet 1500.