Wiring 2012 Cadillac SRX so that Third Brake Light Operates While Flat Towing

Updated 09/26/2012 | Published 09/24/2012

Products Featured in This Question

Roadmaster 6-Diode Universal Wiring Kit for Towed Vehicles with Separate Lighting

(61)

$193.68

Hook Probe Circuit Tester

(60)

$12.41

Roadmaster Hy-Power Diode - (Qty 1)

(336)

$18.91

Question:

I ordered from you, a diode wiring kit for my Cad. I have wired cars before,but I cant find the wire for the center stop light. I would like to have the center stop light work if possible. It does not seam to be connected to the right or left brake light wires. Do you have any ideas that might help? Thanks

asked by: Michael B

Expert Reply:

Although it is not required by law, you can indeed tie in the third brake lamp so that it operates when your SRX is connected to the motorhome. You will need an additional diode, part # RM-790 to prevent backfeed into the SRX. The diode would be wired as shown in the diagram I have produced for you.

I have looked online and have not been able to find any information regarding the location of the wiring harness that feeds the third brake light. Your best bet would be to check behind the trim panels behind the C pillar, looking for a wiring harness that runs up the inside and up under the headliner. Use a circuit tester like part # PTW2993 to ensure you have the correct wire. Trace the wire back down behind the side trim panels, which would be a good spot to install the extra diode shown in the diagram. I wish I had more specific information for you.

expert reply by: Mike L