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How to Test Brake Controller without Trailer Connected  

Question:

How to check unit without a trailer. 96 chev.

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Expert Reply:

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. Then you can hit the brake pedal of the vehicle and you should see the brake controller operate like normal. You'll need someone to help since it's hard to be at the rear of the vehicle and pressing the brake pedal. If you can't get the controller to operate normally there is a more in-depth way to test it.

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 # 3808, 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.

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:
0
Jameson C

Mike S.

3/23/2024

I did exactly this. However when I tested the brake controller is said connected and then overload. The circuit tester was grounded to the truck. Would this have caused this error?

Etrailer Expert

Jameson C.

3/28/2024

@MikeS At what point does the overload error message occur?

Dan

4/8/2024

Jameson, I bought a podigy P3 brake controller and wanted to test it. I cant even set it up because it doesnt see a trailer. so if i use a prob circuit tester clip one end to truck frame and the prob to the blue pin it will have enough amp to see a trailer and i can set it up thanks

Etrailer Expert

Jameson C.

4/8/2024

@Dan Yes, there will be enough amperage draw that it will sense a connection and function.

Michael

4/13/2024

Hi There. great tips. Mine works fine when I use the slide, even while driving and for long periods. As soon as I use the brake pedal it goes to overload. If it trun the power down under 2 it can cope with it. Any thoughts? much appreciated

Etrailer Expert

Jameson C.

4/15/2024

@Michael Sounds like the red wire of the brake controller is shorting out. I would check where it connects to your vehicle wiring and make sure there's no open wire or obvious signs of a short and fix as needed.

Oldhook58

5/11/2024

What voltage should I see at the brakes when brake is engaged?

Etrailer Expert

Jameson C.

5/13/2024

@Oldhook58 If they are fully engaged pretty close to 12. But varying voltage is how the brakes regulate braking pressure so if you have a lower output setting you won't see the full 12.

Brian C.

7/20/2024

Jamison, I placed the positive end of a volt meter on the controller side of the severed brake wire (blue) and the negative probe on the white ground wire and it's showing 12 volts without the brake pedal depressed or manual override pressed? This does not seem correct to me. Shouldn't I see 12 volts only when either of the two braking methods are applied? Brian 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 # 3808, 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.

Etrailer Expert

Jameson C.

7/21/2024

@BrianC Brake controller is bad. That indicates that an internal problem has developed that can be resolved unfortunately and it would need to be replaced with a new one like the P2 part # 90885.

Brian C.

7/22/2024

@JamesonC Thank you
Etrailer Expert

Jameson C.

7/22/2024

@BrianC no prob!

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