Troubleshooting Emulator Not Allowing Trailer Brake Connection for Primus IQ

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

Question:

Just fishing setting up trailer hitch on 2019 Audi Q7 NAR, with associated trailer control module J345, harness, and Tekonsha Primus controller. Im using the Tekonsha tester/emulator, but it doesnt seem to be providing enough resistance to trigger detection by the control module or the brake controller. I was able to confirm power to 12V pin and lights when I wired a simple test circuit with incandescent bulb, so I know the module detects properly. Unfortunately the Primus brake controller still didnt detect a trailer with that test. Is there a product I can use to test that does provide enough resistance? Or do I just need to plug into an actual trailer? Thanks!

asked by: Bob J

Expert Reply:

Hey Bob, at this point if there's a trailer nearby you can test with I would just do that and go from there. The emulator/testers are handy but all that really matters is how it performs when connected to a trailer so I'd try that and let me know and we can see what would be best solution. Also you can try sliding the manual override of the controller to see what that does as that will force voltage on the circuit for the emulator.

expert reply by: Jameson C