Troubleshooting Brake Controller Installation on 2013 Nissan Xterra

Question:

I have a 2013 Nissan Xterra that seems to be affected by the random blue/black wiring mixup from the factory. See here: https://www.etrailer.com/question-70372.html I installed the Tekonsha 118266 7-Way Tow Harness Wiring Package and have a Tekonsha Primus IQ brake controller. When using with a 7-way connection to my camper, my initial experience was such that brakes were locked up due to constant power on the brake controller output verified with test light at the outside 5 oclock position on the connector. I cut and crossed the blue and black wires at the rear of the vehicle, between the plug into the factory wiring harness and the 7-way connector. Now, the brakes are no longer engaged, but the issue I am having is with the Primus IQ showing an SH code both when the trailer is connected and when it is not connected. What should I do next to troubleshoot? Can I now eliminate the blue/black wire as an issue? Thank you.

asked by: Chris B

Expert Reply:

Thank you for all the details on your Xterra's wiring and brake controller behavior.

The first and easiest troubleshooting step you can take at this point is to unplug the Primus IQ brake controller # TK90160 so it powers down and leave it disconnected for 15 minutes. Then reconnect it and without connecting the trailer see what the display indicates.

If you again see the SH short circuit code then you'll want to check all of the Xterra wiring from the actual socket contacts to your splices and upstream to your vehicle OEM connector. Corrosion or the brake wire rubbing on metal could cause the error message. Note that corrosion can build up inside the socket housing where it is not always easily seen.

If you do not get the SH short circuit code plug in the trailer. If the SH short circuit code appears then check the connector and wiring on the trailer in the same way, looking for corrosion or a damaged brake circuit wire.

You can also easily test the trailer brake circuit independent of the truck by directly connecting 12Vbattery power to the ground and brake circuit contacts on the trailer plug. Please see the linked photo. Two short lengths of wire and a set of jumper cables make this testing pretty easy. With this full power directly applied to the brake circuit you should be able to hear the magnets humming and of course the brakes themselves should engage fully and lock up.

If the brakes do not lock up with this full +12V input then you'll know to focus on the trailer wiring to find the fault. Check from the 7-way plug all the way to the individual brake magnet wiring.

expert reply by: Adam R