Brake Controller Troubleshooting that Doesnt Show Trailer Connection

Question

Question:

I have a curt C24VV controller which I installed on a 2008 Toyota Tacoma, with no OEM tow package. I put in the hitch, the rear 7 pin and 4 pin plugs to the back of the truck prior to installing the controller. When it came time to install the brake controller, I read my truck manual which states the Tacoma is equipped with a plug and play hookup under the dash at the drivers kick plate. Only after I bought the pigtail, I discovered on non equipped tow package trucks, the harness isnt completed from factory. Also after I bought and installed the relay and fuse required in the fuse box. This pushed me to wire the controller direct. I ran all the wires for the controller. 30 amp fuse at the positive battery terminal, ground wire to the battery terminal, wire extending to the back of the trucks 7 pin plug hooked to the blue wire on the plug and tapped into the OEM harness for brake application. When I step on the brakes with no trailer hook up, I get a green light signal on the controller. Otherwise a blank screen without brake application. Which I read in the brake controller manual as normal without the trailer. As soon as I hook the trailer to the truck, the brake controller goes blank. No signal when I apply a brake, no output bars, almost like it loses power. Once I disconnect the plug, I get a steady red light on the controller for 30 seconds or so and it shuts off to a blank display with no brake application. Once I apply brake, I get a green light. Once again, how I see it, normal. I did start the truck this morning and right away, the red light appeared for 30 seconds or so and shut off, returning again to a blank display and green light came on during my brake applications. Im getting a bit bamboozled by this whole thing. The trailer is a 2500lb hybrid trailer 2013. Any help as to a what next step is greatly appreciated!!

asked by: Tim

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Expert Reply:

Based on what you described it sounds like the problem is in the brake output circuit of the brake controller (the blue wire). But you can still test the brake controller to make sure it is installed an functioning properly.

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 part # PTW2993, you should get output to the controller side of the wire you severed. If the manual slide activates the trailer brake output wire properly, try the brake pedal. If the brake pedal activates the brake output properly also then the problem is farther back either in the vehicle wiring or on the trailer.

If either the brake pedal or the manual slide are not functioning properly you will need to test the wires going into the brake controller. Make sure you have power entering the brake controller on the black wire. On the red wire you will only want power when the brake pedal is pressed.

If there is power on the red wire before the brake pedal is pressed you have connected the red wire from the brake controller to the wrong circuit. You would then need to find the brake switch wire that has power ONLY when the brake pedal is activated. This is most likely not your issue but I figured I would mention it anyway.

If these connections check out and the brake controller is properly grounded then there is possibly a problem inside the brake controller.

I am including a link to a video that will show you how to test the wiring on a brake controller.

expert reply by: Jameson C

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