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How to find a brake light trigger point

Finding a brake light trigger point and installing into Mk I Ford Ranger

Note that this bulletin does not apply to models other than the Mk 1.


Since the release of the Tow-Pro in June of 2014, our technical support staff have become aware of difficulties with finding suitable brake light trigger points for some vehicles. Many newer vehicles incorporate Body Controls Modules (BCM’S) which often output brake light signals, rather than DC voltages, that are unsuitable to trigger the Tow-Pro.


In these situations it is important to find a 0V – 12V switch point on the input to the BCM, before any signal modification by the BCM has occurred. Our technical support staff are often asked “Where can I pick up a brake light feed on a Mk I Ford PX Ranger?”


Due to the lighting controls on the Mk I PX Ranger, taking a brake light signal from the brake lights or the brake light wire on the trailer plug is not recommended. This will result in incorrect operation of the Tow-Pro and therefore the trailer brakes. Instead it is recommended to take the brake light trigger from the brake light switch located above the brake pedal in the vehicle (the brake light switch is the lower of the switch).


Pin 2 of the connector to this switch is 0V without the brake depressed and 12V when the brake is pressed. This circuit is also capable of 1A additional load, with the Tow-Pro requiring far less than this.


This information sourced from Body and Equipment Mounting Manual Ford Ranger 2012 (Page 32). The important things to remember when selecting the source for the brake light trigger wire are: 


  • The wire must output a 12V DC voltage when the brake is pressed.
  • The circuit must be able to handle at least 250mA load.
  • If you are unsure contact your vehicle manufacturer, dealer or technical manual.


For further technical support please call REDARC on (08) 8322 4848 and speak to one of our friendly customer support team.


Please click here to view the Tow-Pro Technical Bulletin as a PDF.

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