1. Incorrect Wiring Connections:
* Most likely cause: The most common reason is a simple wiring mistake during the replacement. The brake light switch wire was likely connected to a power source instead of the brake light switch itself, or connected incorrectly to the brake light switch.
* Troubleshooting: Carefully trace the wire from the brake light switch (located near the brake pedal) to the under-dash wiring harness. Check for:
* Incorrect connections: Ensure the wire from the switch is connected correctly to the appropriate terminal in the harness. A wiring diagram for your specific year and model Ram is crucial here. You can often find these online (repair manuals, forums dedicated to Dodge Rams).
* Shorted wires: Look for any bare wires touching each other or grounding against the chassis. This can create a constant circuit.
* Loose connections: Ensure all connections are secure and tightly fastened.
2. Faulty Brake Light Switch:
* Possible cause: While less likely if the problem started *after* the wiring was replaced, it's possible the brake light switch itself is faulty and always sending a signal. This is more likely if the brake lights were working correctly before the wiring work.
* Troubleshooting: Disconnect the brake light switch connector. If the brake lights go out, the switch is likely faulty and needs replacement.
3. Faulty Brake Pedal Switch (or another component mistakenly wired in):
* Less likely but possible: There might be another switch near the brake pedal involved in the system. Or the wire might have been connected to the wrong switch by mistake during the wiring replacement.
* Troubleshooting: A wiring diagram is essential for determining all components involved in the brake light circuit and identifying any possible alternate causes and connections.
4. Short to Power:
* Possible cause: A wire might be shorted to a constant 12V power source.
* Troubleshooting: This requires carefully tracing the wiring harness to identify any wires touching a power source. A multimeter is helpful here.
5. Fuse Issues (Less Likely):
* Possible, but unlikely: While less probable if the lights are *constantly* on, it's worth checking the fuse for the brake lights. A blown fuse would usually mean no lights at all; a short might blow it, but a constantly-on situation implies a different issue.
How to Troubleshoot Further:
1. Obtain a wiring diagram: This is absolutely essential. Without it, you're working blind.
2. Use a multimeter: A multimeter allows you to test for continuity (a complete circuit), voltage (12V), and resistance (measuring the health of components). This is vital for pinpointing the exact problem.
3. Systematic approach: Check each connection one at a time, starting at the brake light switch and following the wire to the under-dash harness and then to the lights.
Important Safety Note: Disconnecting the battery's negative terminal before working with the vehicle's electrical system is crucial to avoid electric shock. If you're not comfortable working with car wiring, it's best to take it to a qualified mechanic. Incorrect wiring could damage other components or create a dangerous situation.
