* Grounding Issue: A common cause is a poor ground connection. The brake lights and parking lights might share a common ground wire, and if that ground is faulty, the current might take an unintended path, causing the parking lights to illuminate when the brake lights are activated.
* Wiring Short: A short circuit in the wiring harness between the brake light circuit and the parking light circuit is another possibility. This could be due to damaged insulation, chafing wires, or a poorly connected wire.
* Faulty Switch: While less likely, a faulty brake light switch could be sending a signal to both the brake lights and the parking lights due to internal shorts or failures.
* Incorrect Wiring: It's possible that the car's wiring was incorrectly modified or repaired at some point, leading to the unintended connection.
Troubleshooting Steps:
1. Inspect the wiring: Carefully examine the wiring harness related to the brake lights and parking lights, looking for any signs of damage, fraying, or loose connections. Pay particular attention to areas where wires might rub against metal parts.
2. Check the grounds: Locate the ground wires for both the brake lights and parking lights. Clean the ground connection points with a wire brush to ensure good electrical contact. Consider temporarily connecting a clean ground wire directly to the car's chassis as a test.
3. Test the brake light switch: See if the switch itself is faulty. A multimeter can be used to test its continuity.
4. Check the fuses: Make sure all relevant fuses are not blown.
5. Use a wiring diagram: A wiring diagram specific to a 1972 Nova is invaluable. This will help you trace the circuits and identify the points of potential problems. You can find these online through various classic car forums and parts suppliers.
If you're not comfortable working with car electrical systems, it's best to take the car to a qualified mechanic. Improperly addressing this issue could lead to further damage or even a fire hazard.
