Troubleshooting Error Code NC on Tekonsha Primus IQ Trailer Brake Controller TK90160

Published 11/21/2017

Question:

could please advise re lights flashing a .C. when brake pedal is pressed then the only way to stop flashing is to unplug unit. when when you replug back in it flashes .NC. Then to . . Then press brake pedal we get flashing .C. this no trailer plugged in to vehicle. regards

asked by: Gary

Expert Reply:

With the Tekonsha Primus IQ trailer brake controller # TK90160 the error code NC indicates that the controller no longer senses an electrical connection to the trailer's electric brake magnets. There are several possible causes for this: the trailer is not plugged in to the vehicle; the brake controller has lost connection to the trailer brake circuit due to corrosion in the connectors; or the trailer brake magnet's ground wires are loose.

If you get the code .C. when no trailer is connected this suggests that the issue could be in the vehicle trailer socket or the wiring leading to it. I suggest inspecting the 7-way socket for signs of a bent or corroded electrical contact, or trapped moisture or foreign material that could be interfering with the connection. Sometimes corrosion will occur INSIDE the socket where it is very tough to see at first glance. If possible, unplug the 7-way socket from the wiring that connects to the back it; this will allow you to inspect both the socket itself and the wiring leading to is.

You can also inspect the (usually blue) wire leading to the 7-way, the wire that carries the brake signal. Look for cracked insulation and spots where the wire may touch the frame. Please refer to the linked trailer wiring article to see which contact carries this circuit; it is the contact at the 5-o-clock position as you look at the socket. The ground contact is the one to the left of it, at the 7-o-clock position.

Also make sure the main ground wire for your 7-way is solidly attached to a clean bare metal surface.

The Primus instructions and a helpful troubleshooting article are linked for you.

expert reply by: Adam R