HD Pass-Thru Cable Power Reroute Guide

This guide provides instructions on how to reroute power to the HD Pass-Thru cables. These steps are necessary to resolve an issue with some heavy-duty vehicle diagnostic ports not providing consistent power to the device. Before you continue, please be sure you have properly tested the device-to-vehicle connection for possible blown fuses or a master battery cut-off switch.

Disconnect the HD Pass-Thru cable from the vehicle’s diagnostic port BEFORE making any of the following adjustments.

Tools you will need include a digital multimeter, one razor knife, electrical tape, wire stripper, insulated crimper, wire cutter, three butt connectors, 16-18 AWG wire, one fuse holder, one 3-amp fuse, and five cable ties.

Installation Steps

The following steps provide an overview of the installation process:

  1. Cable Identification.
  2. Cable Preparation.
  3. Circuit Connection.
  4. Connect Remaining Wire to Inline Fuse Holder.

  1. 1. Cable Identification.

    The color wire requiring the adjustment will depend on the type of cable being installed. Please use the table below to identify the cable you have before moving forward.

    The Part Numbers listed above can be found printed on the cable.

  2. 2. Cable Preparation

    1. Locate the section of cable that connects the replacement diagnostic port to GPS Device. The illustrations below indicate which section of the cable is being modified:
    2. Being careful not to cut into the wires, remove approximately 4 in. (10 cm.) of sheathing from this portion of the cable.
    3. Depending on the type of cable you identified in Step 1, locate and cut the color wire indicated below.
      9-Pin 250K – RED Wire

      9-Pin 500K – ORANGE Wire

      16-Pin Hino – RED Wire

      16-Pin Volvo/Mack – ORANGE Wire

    4. Be sure you have identified the correct cable and color before cutting into any wires. Supplying power to the incorrect color could cause serious device and vehicle damage.

    5. Using a wire cutter, cut the wire in the middle and strip 1in of sheathing from the wire which leads to the GPS device connection.

      RED Wire:

      • 5C909-2
      • 5C972-2

      Orange Wire:

      • 5C992-2
      • 5C973-2
      • 5C709M-2
      • 5C991M-2
      • 5C990M-2
      • 5C734M-2

    6. Using insulated crimpers, crimp a butt connector to the wire leading to replacement diagnostic port, and another to the wire leading to the GPS device before taping everything off.

  3. 3. Circuit Connection.

    1. Using a digital multimeter, locate a vehicle circuit which provides a continuous 12-24 VDC (+) whether the engine is On or Off OR whether or not the master cut-off is On or Off
    2. Once you have identified the constant power source, use the poke and wrap method to connect an inline fuse holder to this wire and extend the other end to the HD Pass-Thru cable.
      1. On the harness red wire, strip off 1 1/2in. (4cm) of insulation, and twist the wire strands before poking it through the loop created for the Ignition source.
      2. Squeeze the loop shut, and tightly wrap the bare wire around the exposed wire at least three times.
      3. Fold the wire back, and generously wrap electrical tape around the connection, crossing over the insulation on both sides.
      4. Secure the connection with one zip tie directly over the wire-to-wire connection, and another zip tie on a stress loop created about 1in. (2.5cm) away from the connection.

  4. 4. Connect Remaining Wire to Inline Fuse Holder

    Using a butt connector, connect the loose end of the inline fuse holder to the exposed wire on the HD Pass-Thru cable, then secure this connection using electrical tape and a zip tie.

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