Diagnostic Test

WARNING: This page is about a different car, the 2024 RAM ProMaster EV. However, it is still accessible from the selected car via links, so may be relevant.

CHECK FOR AN ACTIVE DTC
NOTE:
The CAN C2 Bus may also be known as the CAN CH Bus.

NOTE:
If the scan tool will not communicate with the vehicle, proceed to SCAN TOOL DOES NOT COMMUNICATE WITH VEHICLE. Refer to SCAN TOOL WILL NOT COMMUNICATE WITH VEHICLE .

NOTE:
Due to a loss of communication on the CAN Bus, multiple Electrical Control Units (ECUs) may not communicate on the network. If the scan tool communicates with the vehicle, but does not communicate with the Body Control Module (BCM), Go To 2 .
1. Turn the ignition on.
2. With the scan tool, read the BCM DTCs and record on the repair order.
3. With the scan tool, erase the BCM DTCs.
4. Turn the ignition off and wait 10 seconds.
5. Turn the ignition on.
6. With the scan tool, read the BCM DTCs.
  Did the DTC return?
  
  Yes
  - Go To Next Step.
  No
  - Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
CHECK THE CAN CH BUS (+) AND CAN CH BUS (-) CIRCUITS FOR A SHORT TO VOLTAGE
1. Make sure the ignition is on.
2. Using the appropriate back-probe pins, back-probe and measure the voltage on the CAN CH Bus (+) circuit at Security Gateway (SGW) Module harness connector.
3. Using the appropriate back-probe pins, back-probe and measure the voltage on the CAN CH Bus (-) circuit at SGW Module harness connector.
  Is the voltage above 5.0 volts on the CAN CH Bus (+) or CAN CH Bus (-) circuit?
  
  Yes
  - Diagnose the short to voltage on the CAN CH Bus (+) or CAN CH Bus (-) circuit. Disconnecting modules on the CAN CH Bus can isolate portions of the bus to assist in determining the location of the concern. Repair the circuit concern or replace the module, that when disconnected, allowed the bus voltage to return to normal.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To Next Step.
CHECK THE CAN CH BUS (+) AND CAN CH BUS (-) CIRCUITS FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect and isolate the negative battery cable.
3. If equipped with Engine Stop Start (ESS), disconnect and isolate the negative auxiliary battery cable.
4. Using the appropriate back-probe pins, back-probe and check for continuity between ground and the CAN CH Bus (+) circuit at SGW Module harness connector.
5. Using the appropriate back-probe pins, back-probe and check for continuity between ground and the CAN CH Bus (-) circuit at SGW Module harness connector.
  Is there continuity between ground and the CAN CH Bus (+) or CAN CH Bus (-) circuit?
  
  Yes
  - Diagnose the short to ground on the CAN CH Bus (+) or CAN CH Bus (-) circuit. Disconnecting modules on the CAN CH Bus can isolate portions of the bus to assist in determining the location of the concern. Repair the circuit concern or replace the module that when disconnected allowed the bus voltage to return to normal.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To Next Step.
CHECK FOR CORRECT CAN CH BUS TERMINATION RESISTANCE
NOTE:
Total resistance of CAN networks must be measured with the battery disconnected. The average resistance is approximately 60 Ohms. The termination resistors are integral to the dominant modules.

NOTE:
If resistances are higher than expected, inspect connectors for corrosion or poor terminal tension.

NOTE:
The CAN CH Bus Dominant Modules are the Antilock Brake Control Module (ABS) and the Occupant Restraint Module (ORC). Refer to COMMUNICATION, DESCRIPTION AND OPERATION .
1. Disconnect the battery.
2. Disconnect the SGW Module connector.
3. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN CH Bus (+) circuit and CAN CH Bus (-) circuit at the SGW Module harness connector.
  If the resistance is approximately 60 Ohms (resistance is correct):
  - Go To 13.
  If the is resistance approximately 120 Ohms (resistance indicates an open or missing dominant module) :
  - Go To 10.
  If the resistance less than 55 Ohms (resistance indicates a shorted module or a short between the CAN C1 (+) and (-) circuits):
  - Go To 5.
  If the resistance is higher than 125 Ohms (resistance indicates an open circuit on the CAN CH (+) and/or (-) circuits):
  - Go To 8.
ISOLATE THE SHORT BETWEEN THE CAN CH (+) AND CAN CH (-)
1. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN CH Bus (+) circuit and CAN CH Bus (-) circuit at the SGW Module harness connector.
2. Continue to monitor the resistance at the SGW connector.
3. Disconnect the related BCM harness connector (which will split the bus).
  Is the resistance at the SGW Module below 55 Ohms?
  
  Yes
  - Go To Next Step.
  No
  - Go To 6.
ISOLATE THE SHORT BETWEEN THE CAN CH (+) AND CAN CH (-) BETWEEN THE SGW MODULE AND BCM
1. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN CH Bus (+) circuit and CAN C1 Bus (-) circuit at the SGW Module harness connector.
2. Continue to Monitor the resistance between CAN CH (+) and CAN CH (-) at the SGW connector.
3. Refer to Wiring diagrams and disconnect all of the CAN CH modules connected to the SGW Module/CAN CH Bus (+) circuit and CAN CH Bus (-) circuits.
  Is the resistance below 55 Ohms ?
  
  Yes
  - Repair the shorted circuit.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Replace the module, that when disconnected, allows the CAN Bus resistance between the CAN CH (+) and CAN CH (-) circuits to return to normal (over 55 Ohms).
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
ISOLATE THE SHORT BETWEEN THE CAN CH (+) AND CAN CH (-) BETWEEN BCM AND ABS MODULE
1. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN CH Bus (+) circuit and CAN CH Bus (-) circuit at the ABS Module harness connector.
2. Continue to monitor the resistance at the ABS Module connector. Refer to Wiring diagrams and disconnect all of the CAN CH modules connected between the BCM and ABS Module/CAN CH Bus (+) circuit and CAN CH Bus (-) circuits.
  Is the resistance below 55 Ohms?
  
  Yes
  - Repair the shorted circuit or replace the module, that when disconnected, allows the CAN Bus resistance between the CAN C1 (+) and CAN C1 (-) circuits to return to normal (over 55 Ohms).
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 13.
ISOLATE AND CHECK THE CAN CH (+) CIRCUIT FOR AN OPEN
1. Disconnect the related BCM connector.
2. Measure the resistance on CAN CH (+) circuit between the BCM connector and the SGW Module connector.
  Is the resistance over 3 Ohms?
  
  Yes
  - Repair the open circuit, continue with Next Step.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To Next Step.
ISOLATE AND CHECK THE CAN CH (-) CIRCUIT FOR AN OPEN
1. Disconnect the related BCM connector.
2. Measure the resistance on CAN CH (-) circuit between the BCM connector and the SGW Module connector.
  Is the resistance over 3 Ohms?
  
  Yes
  - Repair the open circuit.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 13.
CHECK THE CAN CH BUS TERMINATION RESISTANCE AT THE ANTILOCK BRAKE MODULE (ABS)
1. Disconnect the related ABS.
2. Using the appropriate back-probe pins, back-probe and measure the resistance of the CAN CH Bus (+) circuit and CAN CH Bus (-) circuit at the related ABS harness connector.
  Is the resistance approximately 120 Ohms?
  
  Yes
  - Go To 12.
  No
  - Go To Next Step.
CHECK THE CAN CH BUS TERMINATION RESISTANCE AT THE OCCUPANT RESTRAINT CONTROLLER (ORC)
NOTE:
Occupant Restraints Controller (ORC) installation and mounting bolt torque is crucial for proper operation.

WARNING:
To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to take the proper precautions could result in accidental airbag deployment.
1. Reconnect the ABS.
2. Disconnect the ORC.
3. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN CH Bus (+) circuit and CAN CH Bus (-) circuit at the ORC.
  Is the resistance approximately 120 Ohms?
  
  Yes
  - Replace the Occupant Restraints Controller (ORC) in accordance with the Service Information. Refer to CONTROLLER, OCCUPANT RESTRAINT (ORC), REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
CHECK THE ANTILOCK BRAKE MODULE (ABS) RELATED HARNESS CONNECTIONS
1. Disconnect all ABS harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Perform a terminal drag test on each connector terminal to verify proper terminal tension.
  Repair any conditions that are found.
5. Reconnect all ABS harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
  WARNING:
  To avoid possible serious or fatal injury, check brake capability is available before road testing.
9. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read BCM DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Anti-lock Brake System (ABS) Module in accordance with the Service Information. Refer to MODULE, BRAKE SYSTEM CONTROL (BSCM), REMOVAL AND INSTALLATION .
  - Perform ABS VERIFICATION TEST. Refer to BSCM VERIFICATION TEST .
  No
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  - Test complete.
CHECK RELATED BCM HARNESS CONNECTIONS
1. Disconnect all BCM harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Perform a terminal drag test on each connector terminal to verify proper terminal tension.
  Repair any conditions that are found.
5. Reconnect all BCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read BCM DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Body Control Module (BCM) in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  - Test complete.