The DRL function is often integrated into the body control module (BCM) or other control modules, and the headlight relay itself might be used in conjunction with the BCM's control signal to activate the DRLs at reduced intensity. There isn't a separate dedicated relay for just the DRL function in most cases.
To find the relevant components, you'll need to:
1. Consult your owner's manual: This might provide a wiring diagram or at least indicate the location of the relevant fuses or relays.
2. Check your wiring diagrams: A wiring diagram specific to your truck's year, make, model, and trim level will be your best resource. You can often find these online through repair manual websites like Haynes or Chilton, or through online forums dedicated to Chevy trucks.
3. Trace the wiring: If you have the diagrams, you can follow the wiring from the headlights (or the DRL circuits if your truck has separate DRL bulbs) to identify any relevant relays or modules.
4. Look for headlamp relays: The headlight relays are a likely place to find components related to DRL operation. These are usually in the underhood fuse box or a separate relay center.
In short: Don't expect to find a single "DRL relay." The system is more likely integrated into a larger control module (BCM) or uses existing relays in conjunction with electronic control. The best way to diagnose is using the wiring diagrams and tracing the wiring.
