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Home >> Jeep >> 2021 >> Compass Trailhawk >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Communication - Non-DTC Based Diagnostics >> Diagnosis And Testing >> Multiple Modules Will Not Communicate With Can C, Ch Or IHS >> Testing With The MOPAR® Diagnostic Splice Block Kit

Testing With The MOPAR® Diagnostic Splice Block Kit

NOTE:

The Scan Tool Topology may not correctly display the CAN Bus module layout and should not be used when diagnosing a CAN Bus network with splice block connectors.

The splice block connector numbers, locations, CAN Bus circuits, and CAN Bus network flow (To Main BUS and From Main BUS) must  be determined before proceeding to diagnose the CAN Bus. To help determine the flow of the CAN Bus network, Use the appropriate SYSTEM WIRING DIAGRAMS, Component Views, Connector End Views and the splice block connector terminal information on the back-side of the (special tool #2028700080, Kit, Diagnostic Splice Block).

NOTE:

Individually opening and closing the From Main BUS, To Main BUS, and Node switches while viewing the scan tool topology screen and monitoring which communication DTCs are set can help determine the direction of the CAN Bus failure. For best results, allow the network and scan tool to update before opening or closing other switches.

NOTE:

The High and Low testing ports on the (special tool #2028700080, Kit, Diagnostic Splice Block) are equivalent to the CAN C, CH and IHS Bus (+) and (-) circuits and can be used to take CAN Bus measurements.

Perform the following steps to determine the To Main BUS and From Main BUS flow of the CAN Bus network:

  1. Due to various vehicle options, the VIN must  be used in the Wiring Diagrams for accurate splice block connector configurations, locations, and CAN Bus circuits.
  2. With the ignition ON, view the scan tool topology screen and note any module(s) in Red.
  3. Using the Bus Topology Locations in Wiring Diagrams, locate the single splice block connector closest to the module(s) in Red.
  4. Using the Location Views in the Wiring Diagrams, locate the splice block connector on the vehicle where the (special tool #2028700080, Kit, Diagnostic Splice Block) will be connected.
  5. Using the Connector End Views in Wiring Diagrams, determine the CAN Bus circuits to be tested.
  6. Using the Connector End Views in Wiring Diagrams, match the CAN Bus connector terminals with the splice block connector terminal information on the back-side of the (special tool #2028700080, Kit, Diagnostic Splice Block) and determine the To Main BUS and From Main BUS flow of the CAN Bus.
NOTE:

Opening and Closing the Node 1-6 switches, while measuring the voltage and resistance on the CAN Bus circuits, along with the Wiring Diagrams and the splice block connector terminal information on the back-side of the (special tool #2028700080, Kit, Diagnostic Splice Block), can help determine if a module or CAN Bus circuit within the splice block connector being used for testing is the cause of the CAN Bus failure.

Perform the following steps to measure and record the voltage and resistance values of CAN Bus circuits:

  1. Perform the above 6 steps and determine the To Main BUS and From Main BUS flow of the CAN Bus network before proceeding.
  2. Make sure all of the switches on the (special tool #2028700080, Kit, Diagnostic Splice Block) are closed before performing the following steps.
  3. With the ignition OFF, connect the (special tool #2028700080, Kit, Diagnostic Splice Block) to the splice block connector where the testing will occur.
  4. With the ignition ON, use a DVOM to measure and record the voltage  on the CAN Bus (+) circuit at the To Main BUS. Connect the (-) lead to a known good ground and connect the (+) lead to the High testing port on the (special tool #2028700080, Kit, Diagnostic Splice Block).
  5. With the ignition ON, use a DVOM to measure and record the voltage  on the CAN Bus (-) circuit at the To Main BUS. Connect the (-) lead to a known good ground and connect the (+) lead to the Low testing port on the (special tool #2028700080, Kit, Diagnostic Splice Block).
  6. Repeat steps 4 and 5 to measure and record the voltage  on the CAN Bus (-) and (+) circuits at the From Main BUS High and Low testing ports.
  7. With the battery and auxiliary battery (if equipped with Engine Stop/Start) disconnected, use a DVOM to measure and record the resistance  on the CAN Bus (-) and (+) circuits at the To Main BUS. Connect the (-) lead to the Low testing port and connect the (+) lead to the High testing port on the (special tool #2028700080, Kit, Diagnostic Splice Block).
  8. With the battery and auxiliary battery (if equipped with Engine Stop/Start) disconnected, use a DVOM to measure and record the resistance  on the CAN Bus (-) and (+) circuits at the From Main BUS. Connect the (-) lead to the Low testing port and connect the (+) lead to the High testing port on the (special tool #2028700080, Kit, Diagnostic Splice Block).
  9. Compare the recorded CAN Bus voltage measurements with the above CAN Bus Voltages (Normal Operation) table. For additional information, refer to the appropriate CAN Bus circuit failure below:
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