Credo - Installation

Note: This instruction Guide is for Credo units with a serial number over 4500

For previous versions download the pdf installation guides below

Serial no. under 4500
Download PDF
Serial no. over 4500
Download PDF
Generation B
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Generation B
Pre-assembled Video

Credo Design Features:

  • Wireless remote design with an encoded wireless link.
  • Universal vehicle connection that only needs standard trailer plug wiring on the vehicle and no hard-wired controller permanently mounted in the vehicle.
  • Internal load resistors to present a load to bulb sensing circuits in late model vehicles.
  • Buck/Boost Battery Charger means trailer battery is always charged correctly regardless of vehicle voltage.
  • Output protection to prevent damage from trailer wiring short circuits.

  • Can operate both Electric and Electric/Hydraulic Braking systems.
  • Real feedback of any trailer faults without specialist vehicle wiring.
  • Trailer stop lamps are powered when breakaway switch is activated.
  • Controls and eliminates flashing trailer lights caused by some vehicles when using LED lamps.

Touch Screen Controller

  • The In-cab controller must be connected at all times and located within easy reach of the driver.

  • The vehicle park or head-lights must be switched on when towing the trailer. This energizes the trailer side of the system and also will allow the trailer batteries to charge.

  • Check the plug and socket of the trailer and tow vehicle are securely connected and that the trailer lighting functions all work correctly. A faulty or intermittent lighting connection could mean the brakes do not operate correctly.

  • Ensure the break away cable is securely fastened to the vehicle.

  • Test the emergency brake is working. First adjust the gain control setting to read 75%. Depress emergency stop button fully, and begin to pull forwards while still holding the button down. The trailer brakes should lock the wheels.

  • Do not use the emergency stop feature or breakaway function as a parking brake.

Orientation Guide

Wiring Notes:

  • Do not Earth to Chassis.
  • Keep any Electric/Hydraulic actuators as close as possible to the controller.
  • Keep Battery as close as possible to the controller.
  • Only use LED trailer lights with Credo brake controller.
  • Use a dedicated battery – using the brake controller battery for other systems can compromise that safety of the braking system if another fault occurs that is not related to the brakes.
  • Keep wiring sizes to above minimums.

Circuit Minimum Size Max Length
Vehicle Connection* 10A / 1.0mm² 3m
Tail/Marker Lights 5A / 0.5mm² 10m
Battery 20A / 2.0mm² 1m
Electric Drums 15A / 1.5mm² 8m
Hydraulic Actuator 25A / 4mm² 0.5m

*Extension from supplied length

Mounting / Installation Requirements:

  • Mount to a metal frame member to allow conduction of heat from load resistors away from the Credo – failure to do so means that the Credo can overheat.
  • Bolt to a solid frame member that will not flex during vehicle motion.
  • Trailer tail and marker Lights must be LED with a maximum draw of 0.6A – any additional lights will need to be connected in before the controller.
  • Mount the controller on the trailer draw bar with a clear line of sight to the vehicle – under the chassis or behind and or under any metallic objects that shields the controller will cause interference in the wireless signal. If using a plastic box make sure that there is a way to conduct heat away from the base of the Credo. This can be by 4 bolts connecting to a metal chassis member directly below the Credo of a significant size.

Hydraulic Wiring Diagram

Electric Wiring Diagram

Pre-Assembled Hydraulic Wiring Diagram

Commission / Testing:

Note: This brake controller is controlled by inertia / deceleration which means there is no response if the trailer stationery.

Stationery Testing:

Breakaway switch

  • Gives 97% output which should lock the brakes to their maximum any attempt to tow the trailer should result in the wheels skidding when unladen.

Emergency Stop Override Button

  • The brakes are applied at 75% of the current gain setting (i.e 99% gain will give a 74% brake output) different settings and brake outputs can be tried by adjusting the gain level.

Road Testing:

  • Empty Trailers start with 25% Gain and Sensitivity of 3. Adjust to suit as you drive.

  • Loaded Trailer start with at least 50% Gain and Sensitivity of 3 and adjust to suit.

General Notes:

  • The trailer should not be holding the vehicle back or ‘pulling’ the vehicle when the brakes are used. If so the brakes will be experiencing excessive wear and load.

  • Electric Drums may need bedding in when new or replaced. This can be done setting the Gain to about 30-35% and holding the emergency stop for approx. 0.5km while travelling at 40-50kmh. Do this in a quiet area where there is little other traffic.



Possible Causes


In-cab controller shows ‘Low Trailer Battery’ warning (old style In-cab Controller shows Eb Error)


No tail lights / tail lights go out when brakes are applied.
  • Battery is excessively discharged.
  • Bad connection between trailer mounted brake controller and battery.
  • Blown battery fuse.
  • Poor connection on battery terminals.
  • Check battery is over 12.5V when disconnected. If lower replace the battery.
  • Check if battery is charging by measuring the battery voltage on the trailer. Measure with the vehicle disconnected which should be at least 12V, then plug  into the vehicle and turn on the lights. After 30 seconds there should be a rise in the battery voltage that shows the Credo pushing charge into the battery. The battery voltage should peak at 14.3V.
  • Check leads, fuse holder and any connections between the battery and controller for poor / corroded connections. Any high resistance joins will cause excessive voltage drop to the controller under braking resulting in the ‘Low Battery’ error.
In-cab controller shows ‘Please Drive with Your Headlights On’ message, even though the headlights are on.

(old style In-cab shows Ec Error).
  • Serial number mismatch between Controller and Trailer.
  • Faulty trailer plug.
  • In-cab controller cannot communicate with the trailer mounted controller due to interference.
  • Incorrect wiring by-passes controller.
  • Recode the Serial number on the
    In-cab remote.
    If they do not match then follow instructions on page 14/15.
  • Check trailer plug pins are not corroded or crushed in, and either spread the pins, remove corrosion or replace the plug.
  • Check the controller to In-cab connection by taking the in-cab unit back to beside the trailer mounted controller, if still error is still present controller needs to be replaced or repaired.
  • Check the vehicle connection goes to only the trailer mounted controller and all tail and marker lights from the controller lights output.
Brakes randomly come on and lock up.


Brake lights stay on when trailer is disconnected.
  • Faulty Break-away switch.
  • Faulty Break-away wiring.
  • In-cab controller has ‘emergency stop’ button pressed.
  • Check breakaway switch and wiring for a short circuit. Replace any faulty components or wiring.
  • Check the breakaway switch is not full of water and dirt. Any leakage of voltage in the breakaway circuit due to water ingress can cause unexpected behaviour on Hydraulic / Electric systems.
  • Make sure In-cab controller is securely mounted on vent holder and emergency stop button not inadvertently pressed.
Braking output on In-cab controller stays at ‘--‘ on the screen when brakes are applied.
  • Faulty trailer plug / vehicle connection.
  • Incorrect wiring bypasses controller.
  • Check and repair trailer plug and vehicle socket and associated wiring – replace any faulty parts.
  • Check vehicle connection goes directly to the controller and does not bypass the controller.
In-cab Controller shows ‘00’ or higher numbers when brakes applied but no braking happens.
  • On electric drums – Faulty wiring or magnets.
  • On hydraulic actuator driven brakes – Faulty wiring or isolator if fitted
  • On electrics check wiring and drum magnets for faulty connections. Typical magnet resistance is approx 2.8 Ohms. 2 Magnets together is 1.4 Ohms and 4 is 0.7 Ohms.
  • On Hydraulic the Blue signal wire should be checked for voltage when the emergency stop being is pressed. If there is some voltage and there is no brakes then call for assistance.
Wheel locking up on one side of the trailer.
  • Wiring connected to one side of the trailer first and then to the other.
  • Shorted or open circuit magnets.
  • Connect magnets into a star connection.
  • Check magnet resistance.

Warranty Terms and Conditions


Trailequip Ltd warrants that the mechanical and electrical components of the TRAILPARTS/CREDO products as listed below will be free of defects in material and workmanship for a period of eighteen months from the original date of purchase.

Whilst we take every effort to ensure compatibility with all known vehicles we cannot guarantee 100% compatibility for all vehicles.

To obtain any warranty service, you must provide Trailequip Ltd with proof of purchase, such as a copy of your tax invoice or purchase receipt, which will include a purchase date and the serial number of your product. This warranty does not cover the removal or re-fitting of the product.

TRAILPARTS/CREDO will, at its discretion, repair, replace or refund the purchase price of a defective product or component, provided you return the defective product or component during the warranty period, freight charges prepaid, to Trailequip Ltd or to an authorized TRAILPARTS/CREDO dealer or stockist. Attach your name, address, email address, telephone number, a description of the problem, and a copy of the tax invoice or purchase receipt listing the date of purchase and the TRAILPARTS/CREDO serial number of the defective product.

This warranty does not apply if the product has been damaged by misuse, overloading, impact, modification, improper installation. This warranty is void if any TRAILPARTS/ CREDO serial number has been removed, altered, or defaced.

Please contact the below for warranty service or support:

C/ Trailequip Ltd
2 Tuna Street
Dargaville 0310
New Zealand

New Zealand Phone:  0800 487 245
International Phone:   +649 439 5508
Australia Phone:   1300 538 598