Prodigy Brake Controller Shows SH and oL Error Codes on a 2000 GMC Sierra
Question:
Whom ever, Iam getting an SHand when I use the brake I get a small 0 and a large L on display.indicating a short on the brake wire circuit,but only when trailer is hooked to trk.followed blue wire from plug,it goes in to a junction box then to the conector that when trailer becomes disconnected it applies brakes.all seems ok.then I unhooked the rear axle brakes,same.then reconnected rear and disconnected frt brakes,same.then I disconnected both axles,same.i think the problem is in my trk,it is a 2000 gmc sieara 1500 pick up, and had all the oem plugs under dash.for the hook ups.probably need to run a new blue wire.i have not yet inspected the blue wire on trk.any other advise would be greatly appricated.
asked by: George F
Helpful Expert Reply:
The SH error does indicate a short and the oL indicates an overload condition. The first things to check and the easiest are the vehicle and trailer side connectors. Dirt and corrosion can cause this problem. Make sure the vehicle and trailer side connectors are clean and free of corrosion at the pins and in backs where the wires attach.
You can test to see if the problem is the brake controller or the wiring somewhere between the controller and the trailer connector. You can test the brake output pin at the trailer connector and it should only show power with the manual override. If it shows power any other time then there is a short somewhere between the connector and the brake controller you will need to track down.
To test the controller, in the truck cab you will need to sever the blue wire several inches from the back of the controller. Then use a circuit tester such as # PTW2993 to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override. If it shows power at idle, then there is something wrong with the controller and it will need to be replaced.
If it tests fine, then reconnect the blue wire. Then move on to the truck side trailer connector. Like I mentioned before, many times, dirt or corrosion can cause a short in a trailer connector so with those checked and cleaned you can move on.
If the truck side checks out fine, then it could be the wiring to the brake magnets or the magnets themselves. Inspect the power wires to the magnets and look for pinched, frayed, or damaged wires and fix as needed. Make sure the ground wires are attached to clean and corrosion free bare metal surfaces.
You can visually inspect the magnets and if you can see the copper windings coming through the magnets will need to be replaced. To further test the magnets, you can follow the help article I have linked. I have also included some help articles on testing and troubleshooting brake controllers for you.
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