Why is my Tow-Pro flashing random colours?

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 sequence of random colours.

WHAT DOES RANDOM FLASHING COLOURS MEAN?

This flash code is an indication that the Tow-Pro is unable to detect what the specific issue is, but it’s getting your attention as something isn’t functioning correctly.

CAN I STILL TOW WITH THIS FAULT?

Whist the Tow-Pro will attempt to brake the trailer, the braking performance will be affected. In some cases, the fault can be related to a power supply issue which may result in no trailer braking. It is recommended to avoid towing until the fault can be rectified.

WHAT CAUSES FLASHING RANDOM COLOURS?

This fault is indicating that there is an issue in the electric brake system yet the Tow-Pro is unable to define specifically where the problem is coming from.

HOW TO DETERMINE THE CAUSE OF THIS FAULT?

To determine the cause of this poor connection, 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.

A) Check for short circuit on the brake light (red) circuit

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

1. When there are strands of the brake trigger wire that are protruding or, if the wiring is not securely fastened within the trailer plug, there is a likelihood that the wires may have come into contact with each other.
2. 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.
3. Carefully inspect all the wiring to confirm that the wires are securely fastened beneath the connection screws and that there are no lose wires are present.
4. Pay particular attention to pin 5 (electric brake wire connecting Tow-Pro to trailer braking system) and pin 3 (earth pin).
5. Reassemble the trailer plug covers and refit the trailer base to vehicle. Connect the trailer plug to the trailer base. Reset the Tow-Pro by pressing the override / SwayStop button and check if fault code is still being displayed.

Worn through or compressed Tow-Pro trigger wire: 

1. When a section of the Tow-Pro's brake trigger wire insulation is compromised, and the internal wire strands are exposed resulting in contact with a metal part on either the vehicle or the trailer.
2. Locate the Tow-Pro Main unit (usually mounted under the dashboard).
3. Follow the red wire coming out of Tow-Pro’s main unit 4 pin power harness.
4. Identify any areas where this wire may have been compressed or worn through the insulation meeting a metal part of the vehicle/trailer.
5. If any damage is discovered, assess the extent of the wire damage, and make necessary repairs. Insulate the wire and eliminate the potential for future occurrences.

B) Check for short circuit on Trailer Brake (blue) Circuit

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 plug and the 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.

C) 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 wire in 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.

D) Check Power Supply Circuit 

The power supply circuit incorporates the positive (black) and negative (white) wire power to the Tow-Pro.

Common causes of poor/intermittent power supply

Poor connection between the Tow-Pro input (black) wire and the vehicles start battery positive terminal. It could be caused by loose or poor connection to the battery, shared fuse protection or a faulty/poor circuit breaker:

Checking the connection at the start battery

1. Locate the Tow-Pro fuse protection (can be a fuse or circuit breaker) near the start battery.
2. Check wiring connections at fuse/circuit breaker, check crimp terminal connection to wiring and/or solder connections.
3. Check the connection at the start battery positive terminal where the fuse/circuit breaker sources power. Ensure all connections are free from corrosion and are securely fastened.
4. If a circuit breaker is used and all connections don’t present any issues, suggested action is to replace the circuit breaker.
5. Re-check operation.

Note: The Tow-Pro power supply (black) wire should source power from the start battery positive circuit through an unshared fuse/circuit breaker. If the power supply is shared, separate the circuits and fuse them independently.

Common causes of poor/intermittent ground (earth)

Poor connection between the Tow-Pro ground (white) wire and vehicles ground circuit could be caused by a painted surface, loose grounding bolt, bad eyelet crimp or bad solder joint (if applicable):

1. Locate the Tow-Pro main unit under the dashboard and follow the white wire on the main 4 pin connector.
2. Trace the white wire from main unit to determine location of connection to vehicles ground.
3. Check connection point to ensure:
   • There is metal to metal contact between the vehicle ground and eyelet on the main unit ground (white) wire. If the connection is not metal to metal, you will need to remove some of the paint where the earth eyelet comes into contact with the vehicle’s body.
   • The eyelet is suitably crimped to the main unit ground (white) wire. Give the ground (white) wire a slight tug, you should not be able to pull the crimp off the wire.