Diagnostic Test

TESTING CAN BUS USING THE MOPAR SCOPE 

Connect the black pin for each test lead to Chassis ground. Connect the blue lead to CAN (+) and the red lead to CAN (-) for the circuits to be tested.

Courtesy of CHRYSLER GROUP, LLC

1. Start the Mopar Scope.
2. Turn the ignition on.
   NOTE:

   When connected to the vehicle harness correctly, the LEDs on the breakout box will light up to indicate that there is activity on the bus.

3. A waveform should appear.

   The image below is of a normal CAN bus waveform using the Mopar Scope.

   DESCRIPTION	MEASUREMENT
   CHANNEL A	10 volts
   CHANNEL B	10 volts
   TIME BASE	50 μs/div [microseconds / division control]
   ZOOM / VIEW	X1 - HORIZONTAL & VERTICAL

   Courtesy of CHRYSLER GROUP, LLC

   NOTE:

   The waveform should reveal that data is being exchanged continuously along the CAN bus and the peak voltages are correct.

4. Determine the type of CAN-IHS waveform fault the vehicle presently has from below:
   • (+) Short To Ground 

     Courtesy of CHRYSLER GROUP, LLC

   • (-) Short To Ground 

     Courtesy of CHRYSLER GROUP, LLC

   • (+) Short To Voltage 
     NOTE:

     Channel A and B voltage measurements taken at the 20 V range, measurements taken at 10 V range would display a Channel overrange  message.

     Courtesy of CHRYSLER GROUP, LLC

   • (-) Short To Voltage 
     NOTE:

     Channel A and B voltage measurements taken at the 20 V range, measurements taken at 10 V range would display a Channel overrange  message.

     Courtesy of CHRYSLER GROUP, LLC

   • Short Together 

     Courtesy of CHRYSLER GROUP, LLC

   • (+) Circuit Open 
   • (-) Circuit Open 
   • ECU Influence 

   Did the Mopar Scope show the CAN-IHS bus waveform fault?

   • Use the appropriate SYSTEM WIRING DIAGRAMS as a guide to follow the path of the circuit(s) to isolate the fault further and then repair / replace as needed.
   • The condition that originally caused the concern may not be present at this time.
   • Continue to use the Mopar Scope and wiring diagrams as a guide to trace the circuits and look for any in-line connectors where the fault could occur intermittently by wiggling the wire harness and connectors.
   • Look for any chafed, pierced, pinched, or partially broken wires.
   • Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors.
   • Perform any Technical Service Bulletins (TSBs) that may apply.