Why is my Tow-Pro flashing yellow and one red?

This information is applicable to the following Tow-Pro Electric Brake Controllers:

• Tow-Pro Elite V2 (EBRH-ACCV2)
• Tow-Pro Elite V3 (EBRH-ACCV3)
• Tow-Pro Classic (EBRHV2)

HOW WILL THIS APPEAR?

The Tow-Pro remote head will display a yellow light with a single flash of red.

WHAT DOES YELLOW AND ONE RED FLASH MEAN?

This is a fault code that is indicating the Tow-Pro output wire (blue) is shorted to ground (earth).

CAN I STILL TOW WITH THIS FAULT?

Whist the Tow-Pro will attempt to brake the trailer, the braking performance may be affected. It is recommended to avoid towing until the fault can be rectified.

WHAT CAUSES THE YELLOW AND ONE RED FLASHING FAULT? 

The Tow-Pro unit has detected a direct connection of the brake output wire (blue) to the vehicle’s ground (earth). The purpose of the Tow-Pro brake output wire is to provide a connection between the Tow-Pro and the trailer’s braking system. To activate the trailer brakes, the Tow-Pro outputs a positive voltage from the brake controller module out through the brake output wire which supplies power to the trailer’s brakes.

In this fault mode, the Tow-Pro does not identify a connection of the brake output wire to the braking system but instead detects a direct connection to the ground, which is commonly referred to as a short circuit. If the Tow-Pro were to apply voltage in this scenario, it could result in the Tow-Pro fuse blowing or potentially causing damage to the wiring.

HOW TO DETERMINE THE CAUSE OF THIS FAULT?

To determine the cause of this short circuit, it will require diagnostic testing. REDARC recommends seeking the support of an installer where possible, however please see below a list of the common causes and repairs.

COMMON CAUSES OF THE 'FLASHING YELLOW AND ONE RED' FAULT

A. Inadequately secured or loose wiring in the trailer plug (on the trailer) and the trailer base (on the vehicle)

When there are strands of wire protruding or if the wiring is not securely fastened within the trailer plug, there is a likelihood that the wires may come into contact with each other.

1. Remove the covers from both the trailer plug and the trailer base to facilitate access. If necessary, detach the trailer base from its vehicle mount.
2. Carefully inspect all the wiring to confirm that the wires are securely fastened beneath the connection screws and no loose wires are present.
3. Pay particular attention to pin 5 (Output wire (blue) that connects the Tow-Pro unit to trailer electric brakes) and pin 3 (earth pin).
4. Reassemble covers and refit base to vehicle, connect trailer plug to base and check for Tow-Pro LED activation.

B. Rubbed through output wire between the main unit and the trailer brakes

You will need to determine whether the short circuit is in the vehicle or the trailer.

A quick way of determining this is to disconnect the trailer plug from the vehicle and connect a test light between pin 5, at the vehicle side of the trailer plug, and ground. Press and release the vehicle’s brake pedal to reset the Tow-Pro then check the Tow-Pro remote head for the fault code.

If the fault code remains, the short circuit is in the vehicle.

If the fault code clears and the Tow-Pro remote head is now blue or green, the short circuit is in the trailer.

PROCESS TO FIND AND FIX RUBBED THROUGH OUTPUT WIRES

1. Starting at the trailer plug, trace the Tow-Pro brake output wire (Blue - pin 5) checking for any damage or signs of rubbing that has caused the copper of the wire to come in contact with a metal part of the vehicle or trailer.
2. If damage is found, insulate the cable with electrical tape or heat shrink and add further protection to the cable such as convoluted tubing. Secure the wiring to ensure damage does not reoccur.
3. Re-connect the trailer, press and release the brake and check the Tow-Pro remote head to see if the fault has cleared.