Troubleshooting Primus IQ Brake Controller Showing SH Code With Trailer Disconnected

Question

Question:

My unit has Sh error all the time even with the wire to the trailer not connected

asked by: Matt

0

Expert Reply:

The SH display you are getting on your Primus Brake Controller, part # TK90160 is typically caused by a short in the wiring.

Per my contact at Tekonsha they said that this problem can often be caused by some test lights if you are using test lights. To troubleshoot the problem, start by inspecting the trailer and vehicle side connectors for corrosion build up and clean or replace parts as needed to see if that takes care of the issue. I have attached a helpful article that explains how to troubleshoot brake controller installations.

expert reply by: Jeffrey L

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Answer 1

Although the Tekonsha Prodigy P3 #90195 and Primus IQ #TK90160 electric brake controllers are very similar they do have some key differences as well. For one the P3 is designed to work with electric and electric over hydraulic brake systems. The…

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Answer 2

I have a suspicion about what might be causing the problem you mention. Do your trucks have 6-way trailer connectors? Or, do the trucks have 7-way connectors, but you are using a 6-way to 7-way adapters because the trailers use 6-way connectors?…

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Answer 3

When you disconnect or unplug a brake controller you are "reseting" it so what you are most likely encountering is an internal problem with your brake controller that once it gets reset it starts to work again till the internal problem…

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Answer 4

Something is obviously causing a voltage drop between the brake controller and the trailer connector. The usual culprit in this type of situation is a break in the wire or a corroded wire. Check the wiring under the truck. You should be able to trace…

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Answer 5

Testing the brake controller is fairly easy. Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like the Quickee Tester, part #PTW2993, you should get…

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Answer 6

If you are only getting 1.5 volts at your brakes then there is an issue, but there is not a fuse that controls the brakes. There are a number of possible issues so you will need to find out if the issue is on the brake controller, truck, or trailer.…

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Answer 7

With the brake controller gain turned all the way up, you should be seeing closer to 12-volts at your trailer connector. You are losing voltage somewhere between the brake controller and the trailer connector. I am assuming that by electric brake…

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Answer 8

Its not uncommon for there to be slight voltage drop off over a certain distance but with the brake controller set to the maximum you should still be getting 12 volts at the brake magnets. We need to determine if the low voltage is coming from the…

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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

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 12

You do have the option to utilize the air brakes on your 2023 Freightliner Cascadia to control electric trailer brakes using the Hayes Air Actuated Trailer Brake Controller, part #HA100400C. However, we mostly recommend just using an electric brake…

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