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.

READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN
WARNING:
On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury.

Read the HIGH-VOLTAGE SAFETY PROCEDURES. Refer to HIGH VOLTAGE SAFETY PROCEDURES .

When the HIGH-VOLTAGE POWER-DOWN PROCEDURE is necessary. Refer to VEHICLE HIGH VOLTAGE POWER DOWN .
1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
2. For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
3. With the scan tool, erase all DTCs.
4. Turn the ignition off for a minimum of 10.0 seconds.
5. Turn the ignition on.
6. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
7. With the scan tool, read 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 (D442) CAN C1 BUS (+) AND (D443) CAN C1 BUS (-) CIRCUITS FOR A SHORT TO VOLTAGE
NOTE:
Disconnecting the Radio Frequency (RF) Hub Module or BCM may result in a loss of ignition status messages and may cause scan tool communication concerns.

NOTE:
With a scan tool, refer to the network display to help identify ECUs that are unable to communicate with other ECUs on the CAN network. ECUs unable to communicate on the network will appear in red.
1. Make sure the ignition is on.
2. Using the appropriate back-probe pins, back-probe and measure the voltage on the CAN C1 Bus (+) circuit at Security Gateway (SGW) Module.
3. Using the appropriate back-probe pins, back-probe and measure the voltage on the CAN C1 Bus (-) circuit at SGW Module.
  Is the voltage above 5.0 volts on the CAN C1 Bus (+) or CAN C1 Bus (-) circuit?
  
  Yes
  - Diagnose the short to voltage on the CAN C1 Bus (+) or CAN C1 Bus (-) circuit. Disconnecting each module on the CAN C1 Bus, one at a time, can isolate portions of the CAN Bus to assist in determining the location of the concern. Repair the shorted circuit or replace the module, that when disconnected, allows the CAN Bus voltage to return to normal.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To Next Step.
CHECK THE (D442) CAN C1 BUS (+) AND (D443) CAN C1 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 C1 Bus (+) circuit at SGW Module.
5. Using the appropriate back-probe pins, back-probe and check for continuity between ground and the CAN C1 Bus (-) circuit at SGW Module.
  Is there continuity between ground and the CAN C1 Bus (+) or CAN C1 Bus (-) circuit?
  
  Yes
  - Diagnose the short to ground on the CAN C1 Bus (+) or CAN C1 Bus (-) circuit. Disconnecting each module on the CAN C1 Bus, one at a time, can isolate portions of the CAN Bus to assist in determining the location of the concern. Repair the shorted circuit or replace the module, that when disconnected, allows the CAN 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 C1 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 C1 Bus Dominant Modules are the Body Control Module (BCM) and Electric Vehicle Control Unit (EVCU). 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 C1 Bus (+) circuit and CAN C1 Bus (-) circuit at the SGW Module harness connector.
  If the resistance is approximately 60 Ohms (resistance is correct):
  - Go To the appropriate Diagnostic Information .
  If the is resistance approximately 120 Ohms (resistance indicates an open or missing dominant module) :
  - Go To the appropriate Diagnostic Information .
  If the resistance less than 55 Ohms (resistance indicates a shorted module or a short between the CAN C1 (+) and (-) circuits):
  - Go To the appropriate Diagnostic Information .
  If the resistance is higher than 125 Ohms (resistance indicates an open circuit on the CAN C1 (+) and/or (-) circuits):
  
  Yes
  - Go To the appropriate Diagnostic Information .
LOAD TEST THE POWER SUPPLY AND GROUND CIRCUIT TO THE BCM
Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool, additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES .
1. Disconnect the BCM harness connector.
2. Connect one lead of the load test tool to the power supply circuit and the other lead of the load test tool to the ground circuit.
3. Ensure that the power supply circuit is being powered on.
4. If there is no resistance in either circuit the bulb on the load test tool should be illuminated and bright. Compare the brightness of the bulb in the load test tool to that of a direct connection to battery.
  NOTE:
  To verify with certainty that the circuit is good, perform a simple voltage drop test across the 3156 bulb of the load test tool. The voltage drop across the bulb should be equal to the voltage reading across the battery terminals if there is no resistance in either circuit.
  
  NOTE:
  A 12-volt test light can be substituted for the load test tool, but only if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps.
  
  Is the load test bulb illuminated and bright?
  
  Yes
  - Go To the appropriate Diagnostic Information .
  No
  - If the circuits fail the load test, remove the lead connected to the ground circuit and connect it to a good chassis ground. Check the bulb illumination and voltage drop across the 3156 bulb of the load test tool again. If the bulb is not bright or the voltage drop is still less than battery voltage, repair the battery supply circuit for an open or high resistance. If the bulb is bright or the voltage drop is now equal to battery voltage, repair the ground circuit for an open or high resistance.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
CHECK THE CAN C1 BUS TERMINATION RESISTANCE AT THE BCM
1. Disconnect the related BCM.
2. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN C1 Bus (+) circuit and CAN C1 Bus (-) circuit at the related BCM harness connector.
  Is the resistance approximately 120 Ohms?
  
  Yes
  - Go To the appropriate Diagnostic Information .
  No
  - Go To Next Step.
CHECK THE CAN C1 BUS TERMINATION RESISTANCE AT THE ELECTRIC VEHICLE CONTROL UNIT (EVCU)
1. Reconnect the BCM.
2. Disconnect the EVCU.
3. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN C1 Bus (+) circuit and CAN C1 Bus (-) circuit at the EVCU.
  Is the resistance approximately 120 Ohms?
  
  Yes
  - Go To the appropriate Diagnostic Information .
  No
  - Go to Next Step.
ISOLATE AND CHECK THE CAN C1 (+) CIRCUIT FOR AN OPEN TO MODULE
1. Disconnect the related EVCU connector.
2. Measure the resistance on CAN C1 (+) circuit between the EVCU 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 C1 (-) CIRCUIT FOR AN OPEN TO MODULE
1. Disconnect the related EVCU connector.
2. Measure the resistance on CAN C1 (-) circuit between the EVCU 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
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
ISOLATE THE SHORT BETWEEN THE CAN C1 (+) AND CAN C1 (-)
1. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN C1 Bus (+) circuit and CAN C1 Bus (-) circuit at the BCM Module harness connector.
2. Continue to monitor the resistance at the BCM connector.
3. Disconnect the Cluster (which will split the bus).
  Is the resistance at the BCM below 55 Ohms?
  
  Yes
  - Go To Next Step.
  No
  - Go To the appropriate Diagnostic Information .
ISOLATE THE SHORT BETWEEN THE CAN C1 (+) AND CAN C1 (-) BETWEEN THE CLUSTER, BCM, AND RFH
1. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN C1 Bus (+) circuit and CAN C1 Bus (-) circuit at the BCM Module harness connector.
2. Continue to Monitor the resistance between CAN C1 (+) and CAN C1 (-) at the BCM connector.
3. Disconnect the RFH and the related BCM harness connectors.
  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 C1 (+) and CAN C1 (-) circuits to return to normal (over 55 Ohms).
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
ISOLATE THE SHORT BETWEEN THE CAN C1 (+) AND CAN C1 (-) BETWEEN SGW MODULE AND CLUSTER
1. Using the appropriate back-probe pins, back-probe and measure the resistance between the CAN C1 Bus (+) circuit and CAN C1 Bus (-) circuit at the SGW Module harness connector.
2. Continue to monitor the resistance at the SGW Module connector. Refer to Wiring diagrams and disconnect all of the CAN C1 modules connected to the SGW Module/CAN C1 Bus (+) circuit and CAN C1 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
  - Replace the Instrument Panel Cluster (IPC) in accordance with Service Information. Refer to REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
ISOLATE AND CHECK THE CAN C1 (+) CIRCUIT FOR AN OPEN
1. Disconnect the related BCM connector.
2. Measure the resistance on CAN C1 (+) 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 C1 (-) CIRCUIT FOR AN OPEN
1. Disconnect the related BCM connector.
2. Measure the resistance on CAN C1 (-) 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 the appropriate Diagnostic Information .
CHECK THE EVCU RELATED HARNESS CONNECTIONS
1. Disconnect all EVCU 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 EVCU 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 and program the Electric Vehicle Control Unit (EVCU) in accordance with the Service Information. Refer to ELECTRIC VEHICLE CONTROL UNIT (EVCU) .
  - Perform the Electric Vehicle Control Unit (EVCU) VERIFICATION TEST. Refer to ELECTRIC VEHICLE CONTROL UNIT (EVCU) VERIFICATION TEST .
  No
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  - Test complete.
CHECK THE BCM RELATED 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.