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Home >> Jeep >> 2023 >> Grand Cherokee Altitude, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 38 (2.0L - DTCS B1810 To P0003) >> DTC Troubleshooting >> B2101 Ignition Run/Start Input Low >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN 
    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  2

      No 

  2. CHECK FOR OTHER DTCS 
    1. Refer to the recorded DTCs.

      Are there any Run/Start Relay Control circuit DTCs present in the BCM?

      Yes 

      No 

      • Go To  3
  3. CHECK THE (F942) FUSED IGNITION SWITCH OUTPUT (RUN/START) CIRCUIT FOR PROPER VOLTAGE AT THE PCM HARNESS CONNECTOR 
    1. Turn the ignition off.
    2. Disconnect the PCM C1 harness connector.
      CAUTION:

      Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to conduct the diagnosis.

    3. Connect the special tool # 10436, (GPEC Diagnostic Adapter) to the appropriate PCM connector.
    4. Turn the ignition on.
    5. Measure the voltage on the (F942) Fused Ignition Switch Output circuit at the GPEC Adapter.

      Does the circuit have Battery voltage present?

      Yes 

      • Go To  9

      No 

      • Go To  4
  4. CHECK THE PDC OUTPUT FOR PROPER VOLTAGE 
    1. Turn the ignition off.
    2. Back probe the (F942) Fused Ignition Switch Output circuit at the PDC C1 harness connector.
    3. Turn the ignition on.
    4. Measure the voltage at the (F942) Fused Ignition Switch Output circuit at the PDC C1 harness connector.

      Does the circuit have Battery voltage present?

      Yes 

      • Repair the (F942) Fused Ignition Switch Output circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  5
  5. CHECK FUSE F22 FOR AN OPEN CONDITION (CIRCUIT (F942)) 
    1. Check fuse F22 to determine if it is open.

      Is the fuse open?

      Yes 

      • Repair the short to ground in the (F942) Fused Ignition Switch Output circuit.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  6
  6. CHECK THE RUN/START RELAY SUPPLY VOLTAGE 
    1. Turn the ignition off.
    2. Remove the Run/Start Relay from the PDC.
    3. At the Run/Start Relay socket measure the voltage at the relay supply (terminal 30) in the PDC.

      Does the circuit have Battery voltage present?

      Yes 

      • Go To  7

      No 

      • Go To  8
  7. CHECK THE PDC FOR AN OPEN/HIGH RESISTANCE 
    NOTE:

    This step is checking for high resistance in the PDC portion of the Run/Start Relay output to (F942).

    1. Turn the ignition off.
    2. Disconnect the PDC C1 harness connector.
    3. Measure the resistance between the PDC C1 harness connector terminal for (F942) Fused Ignition Switch Output circuit and the Run/Start Relay output terminal (87) at the Relay socket in the PDC.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Replace the Run/Start Relay in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

  8. CHECK THE PDC BATTERY SUPPLY VOLTAGE 
    1. Measure the Battery Supply voltage to the PDC.

      Does the circuit have Battery voltage present?

      Yes 

      No 

  9. CHECK RELATED PCM AND COMPONENT CONNECTIONS 
    1. Perform any Service Bulletins that apply.
    2. Disconnect all PCM harness connectors.
    3. Disconnect all related in-line harness connections (if equipped).
    4. Disconnect the related component harness connectors.
    5. 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.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    9. With the scan tool, erase DTCs.
    10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    11. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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