Electric Trailer Brake Light Does Not Light Up When Testing with a Hopkins Tow Doctor Tester

Updated 06/07/2012 | Published 06/06/2012

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Question:

We just purchased this tester and are unsure if the electric brake test portion is actually working. We have checked on new and used vehicles and all we get is a faint flicker out of the test light. all the other functions light up bright and are obvious.

asked by: Scott D

Expert Reply:

The replacement unit, # 4010509028 is a replacement for Tow Doctor part # HM50928. It looks like the Tow Doctor version you ordered is # HM50918. The difference is the HM50928 has more features.

To test the brake controller output someone will need to sit in the truck and apply the manual override so that it is sending power back to the trailer connector. Otherwise, what will happen is what you are seeing, a slight flicker of light. That is the brake controller checking to see if a trailer is connected.

If it continues not to work, then use a regular circuit tester like # PTW2993 if needed to test the circuit to see if it is a problem with the brake controller or a problem with the light in the Tow Doctor.

All you need to do is attach the appropriate connector to the vehicle and Tow Doctor. then, someone in the truck needs to run through the various functions (turn signals, brakes, running lights, brake controller, reverse if applicable, and 12 volt power) and the lights will light up if working.

expert reply by: Michael H