What Do the Codes Displayed on the Primus IQ Mean

Updated 08/22/2024 | Published 01/07/2015

Question:

Explaination of codes on display

asked by: Marshall H

Expert Reply:

After installing your Tekonsha Primus IQ Trailer Brake Controller # TK90160 you should see the following two-digit display: n.c. which means "power to brake controller without trailer connected." This displays for 15 seconds then changes to two dots ( . . )

With the trailer connected you will see .c displayed which means "boost feature not engaged," or .c. for "boost feature engaged." A display of b.1, b.2, or b.3 shows the boost level setting. See the chart at right of typical boost settings.

A two-digit display will show the power output. So 5.4 denotes the voltage output to the electric brakes. The range is 0.0 to 13 volts.

The display .r means reverse.

A blank display means there is power to the brake controller but the display is in power saving mode (no motion or activity for at least 15 minutes).

Take a look at the troubleshooting chart at right which explains the error codes. I have also included the installation instructions which contains more information about the brake controller display.

expert reply by: Chris O

click to enlarge

Steven J.

6/14/2024

SH code on controller and po when brake pedal depressed

Bud M.

6/14/2024

@StevenJ So we know the SH code is a short on the brake wire running out of the controller to get to the trailer brake controller. I have never seen a PO error, if you meant to type PL that says there is a power interruption when pressing on the brake pedal. If you have a PO error please let me know what controller you have so I can further investigate that error. The combination of these errors would lead me to first want to bench test the controller to verify if you do have wiring issues on the truck or if you can replicate the issues on a bench test then you know the controller is bad. To bench test the controller you will connect the power and ground to the battery terminals. The blue output wire you can run to a 12 volt incandescent light bulb so you will be able to see power getting to it when you touch the red wire to the 12 volt power representing pressing on the brake pedal.

Steven J.

6/14/2024

@BudM Yes it probably was a PL if my memory serves me correctly. Strange point is it works sometimes and other times Showing both codes. Trailer is 10 years old and I have been questioning the pig tail on the trailer and even one on my truck but other trailers I pull with the truck doesn't have brakes so it's been hard to isolate.

Bud M.

6/14/2024

@StevenJ Intermittent problems like you are have are almost always to do with the wiring or the connectors. As these parts are moving around ever so slightly when you drive that is likely why you get the problem from time to time. You might consider trying out another truck or trailer to see if you get the issue to replicate on either the truck or trailer to help you know where to start looking.

Bill B.

7/18/2024

Sh flashes and then NC at highway speeds What could be causing this

Bryce D.

7/18/2024

@BillB Bill I'd say there is an issue with either your brake line or your brake magnet ground. with the brake line, there could be an open circuit somewhere, or the ground for your brake magnet is bad. These are the two things I'd recommend checking and that could be causing the N.C error code.

Bill B.

7/18/2024

@BryceD this trailer has two axles so four magnetic brakes. None working. So the problem would be before the brakes?. Or one bad ground shuts them all off. Right now SH is showing while traveling and o L while stoped.

Bryce D.

7/18/2024

@BillB So since you're also seeing an S.H error that leads me to believe that it's definitely a short in the brake line. So I'd start before the brake like you said and see if you can track down that short.