Diagnostic Test

1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
2. With the scan tool, run a Vehicle Scan Report or record the Environmental Data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for at least 10.0 seconds.
5. Turn the ignition on.
6. Using the recorded Environmental Data and the When Monitored Conditions, 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 

• Perform the TESTING FOR AN INTERMITTENT CONDITION procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .

1. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
2. Connect the negative lead of the Digital Volt-Ohm Meter (DVOM) to a known good ground.
3. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for voltage.

Is voltage present on the circuit?

Yes 

• Repair the circuit for a short to voltage. Use the wiring diagram as a guide to trace the circuit and identify any in-line connectors that may help isolate the location of the short.
• Perform the DTCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .

No 

• Go To  3

1. The ignition must be off when performing a resistance check to find a short between circuits.
2. Isolate the circuit by disconnecting the ECU and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
3. Connect one lead of the DVOM to the circuit being tested at the ECU harness connector.
4. With the other lead of the DVOM probe all other circuits at the ECU harness connector.

Is there continuity between the circuit being tested and any other circuit?

Yes 

• Repair the circuit for a short to another circuit. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
• Perform the DTCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .

No 

• Go To  4

1. The ignition must be off when checking the continuity of a circuit.
2. Isolate the circuit by disconnecting the ECU and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
3. Before testing a circuit, measure the resistance between the two leads of the DVOM. Note:  Resistance in the meter leads can cause an error in the test results.
4. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
5. Connect the other lead to the circuit being tested at the ECU harness connector and measure the resistance of the circuit.

Is the resistance below 3.0 Ohms?

Yes 

• Go To  5

No 

• Repair the circuit for an open or high resistance.
• Perform the DTCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .

1. Disconnect the RPS harness connector.
2. Measure the resistance across the Signal and Ground terminals at the sensor while moving the Transfer Case Shifter to all four positions. Note the resistance reading for each position.

Is the resistance within specification for each position?

Yes 

• Go To  6

No 

• Replace the RPS in accordance with the Service Information. Refer to DISASSEMBLY AND ASSEMBLY, MP1622C or DISASSEMBLY AND ASSEMBLY, MP3022C .
• Perform the DTCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .

1. Disconnect all DTCM 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 DTCM 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 DTCM DTCs.

    Did the DTC return?

    Yes 

    • Replace the DTCM in accordance with the Service information. Refer to MODULE, DRIVETRAIN CONTROL (DTCM), REMOVAL AND INSTALLATION .
    • Perform the DTCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .

    No 

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