Troubleshooting OL and SH Error Codes on Tekonsha Primus IQ Trailer Brake Controller # TK90160

Question

Question:

works okay for the first few seconds of braking, then goes to oL then to SH code, after awhile will start operating again with the same problem. please advise me of the most likely areas a bad connection could be or maybe its the controller? thanks

asked by: Leon H

0

Expert Reply:

Both the OL (overload) and SH (short) error messages on your Tekonsha Primus IQ Trailer Brake Controller # TK90160 tend to suggest that either your trailer has too many brakes for the controller (6 are the maximum) or that there is a problem in your trailer's brake circuit wiring. You can start by inspecting both the vehicle and trailer connectors for any signs of corrosion or trapped dirt that could cause two circuits to become bridged together. Check both sides of each connector and clean/replace as needed.

Also check the trailer's entire brake circuit wire from the trailer connector all the way along the wiring (looking for signs of cracked or worn insulation) back to each brake assembly. If the brake circuit wire has any damage this could cause a short that would lead to the overload and short circuit error messages. Repair or replace any damaged wire.

If no wiring problems are found you can test the brake magnets themselves by following the procedure outlined in the linked article. You will need a multimeter like # PT89ZR. If you do find your magnets are worn we offer replacements that can be viewed on the included link.

expert reply by: Adam R

0

Mark H.

7/9/2025

Im having this same problem, the codes come on for a bit then the controller works but it will eventually do the same thing again. I tested the power to tow vehicles 7 pin with the power boost engaged on controller and I get 10 volts,is that good enough ? Thank you for your time Mark

Jameson C.

7/9/2025

@MarkH That sounds like an intermittent short on the brake output circuit. This is probably due to a cut or exposed wire that is bouncing around and shorting out. So what you'll want to do is go over the output circuit on the trailer side of the wiring and see if you can find any issues and fix as needed. Also check out the pins of the 7-way for corrosion and sand as needed to clean them off.

Answer 1

The NC on your Tekonsha Primus IQ Brake Controller #TK90160 is simply showing power to the brake controller without a trailer connected. It should do this and display for a 15 seconds before going away. The NC means the brake controller is seeing no…

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Answer 2

The PL error code on the Primus brake controller #TK90160 indicates that power is interrupted when stepping on the brake pedal. Check the connection of the red wire. It should be attached to the brake switch wire that has power only when the brake…

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Answer 3

There are 4 possible reasons why the Tekonsha Primus, #TK90160, is telling you N.C. 1. Trailer not connected to tow vehicle. 2. Trailer connected with open circuit on brake line. 3. Trailer connector disconnected or corroded. 4. Loss of trailer brake…

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Answer 4

You can test your Tekonsha Primus Trailer Brake Controller #TK90160 without the trailer connected by applying a circuit tester like #PTW2993 to the 7-way socket on the vehicle while a helper activates the controller's manual override lever. You…

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Answer 5

Without knowing what brake controller you have I will venture to guess that the OL code you are seeing is an over load code. The OL or overload error code indicates a short in the brake output circuit. Start by examining the trailer connector. Make…

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Answer 6

The first error code, SH, you are seeing on the Prodigy Brake Controller (instructions linked below) means the brake wire sees a short circuit during idle condition. The second code, OL, indicates an overload condition during operation. For the first…

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Answer 7

The SH error code of the #TK90160 means it's detecting a short. This is going to be on the power cable of the controller which is the black wire.

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Answer 8

All the brake controller needs to sense a trailer connection so that you can test it is a slight amperage draw on the output circuit. For that you can use a circuit tester like the part #PTW2993 with one pin grounded and the other on the output pin.…

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Answer 9

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 10

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 11

That's a very good question, we tend to be extra cautious and say to use 10 gauge wire because that would be more than enough. When you get into longer trailers that will end up using a lot of wire the heavier gauge wire becomes more necessary.…

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Answer 12

Hey Jonathon thank you so much for all of that additional information! To haul your bikes behind your class C Sprinter motorhome, while flat towing your Mini, I recommend the Hollywood Racks RV Rider Bike Rack item #HLY64FR and the Roadmaster Dual…

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Troubleshooting OL and SH Error Codes on Tekonsha Primus IQ Trailer Brake Controller # TK90160

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