Troubleshooting Hopkins Trailer Wiring on a 2010 Mercury Grand Marquis

Updated 08/26/2025 | Published 08/25/2025

Question:

Ive got the Hopkins Active Tail Light Converter with Install Kit Part Number: 46255 that Im installing on my 2010 Mercury Grand Marquis. Ive got running lights, left signal and right signal but no 4 way or brake lights. What am I doing wrong?

asked by: Kenneth F

Expert Reply:

Hey Kenneth!

There are 2 red wires on the Hopkins Active Tail Light Converter with Install Kit # 46255 so I'd make sure you have the correct one connected to power, and the correct one connected to the brake light circuit.

If those are connected to the correct circuits, then the next thing to check is that the brake light power is actually getting to the converter box. Check the red brake light wire right before it reaches the converter box, and then again on the green and yellow wires.

Let me know what you find out!

expert reply by: Jon G

Kenneth F.

8/26/2025

None of the above worked. Everything was wired correctly. Now I'm frustrated. So after starting the car I noticed something different. Everything functioned properly. It just didn't function properly with the vehicle not running even though the key was in the "on" position. Go figure. I've never had to do that on any of my other vehicles. Thank you for you quick reply. Etrailer rocks!

Jon G.

8/26/2025

@KennethF That's interesting and good to know! I wonder if it had something to do with how much power was going back to the lights. Regardless, I'm glad to hear it's working properly now!