Diagnostic Test

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 (ECU's) 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 diagnostic procedure. Refer to: TESTING FOR AN INTERMITTENT CONDITION .
ISOLATE AND CHECK THE (K77) TRANSFER CASE POSITION SENSOR INPUT CIRCUIT FOR A SHORT TO GROUND
1. The ignition must be off when checking a circuit for continuity to ground.
2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector 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 the negative lead of the Digital Volt-Ohm Meter (DVOM) to a known good ground.
4. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for continuity between the circuit and ground.
  NOTE:
  When back-probing a circuit at a harness connector, always use an appropriate back probing tool to prevent damage to the connector terminals.
  
  NOTE:
  There should be no continuity between ground and the circuit being tested.
  
  Is there continuity between ground and the circuit being tested?
  
  Yes
  - Repair the circuit for a short to ground. 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: DTCM VERIFICATION TEST .
  No
  - Go To 3
REPLACE THE TRANSFER CASE SELECTOR SWITCH AND CHECK FOR THE DTC TO RETURN
1. Replace the Transfer Case Selector Switch in accordance with the Service Information.
2. Connect the component and ECU harness connectors.
3. Turn the ignition on.
4. With the scan tool, erase DTCs.
5. Using the Environmental Data or When Monitored information above, operate the vehicle under the conditions that set the DTC.
6. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Go To 4
  No
  - Replacing the Transfer Case Selector Switch corrected the condition.
  - Perform the DTCM VERIFICATION TEST. Refer to: DTCM VERIFICATION TEST .
CHECK RELATED HARNESS CONNECTIONS
1. Disconnect all Drivetrain Control Module (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: DRIVETRAIN CONTROL MODULE (DTCM) .
  - Perform the DTCM VERIFICATION TEST. Refer to: DTCM VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the DTCM VERIFICATION TEST. Refer to: DTCM VERIFICATION TEST .