Power Transfer Unit (PTU) And Rear Drive Module (RDM) Systems - Hall Effect Position Sensor Diagnostics

TECH TIPS: 

• If the DTCM connectors or terminals appear corroded from water intrusion, check for a plugged A/C drain causing excessive water in the A/C condenser housing. If the housing fills with water it can drain on the DTCM harness connectors causing damage to the connector or terminals.
• Refer to the DTCM Verification Test information at the bottom of the test procedure to determine any routines or procedures that must be performed for the system to operate correctly after repairs are made. 

HALL SENSOR SUPPLY CIRCUIT FAULT DIAGNOSTICS (C2050-1C):  This fault is designated for the common internal voltage source that provides the supply circuit to each actuator. A short to ground, or short to battery in either of the PTU or RDM position sensor supply circuits can cause the fault to set. A faulty sensor can also pull the supply voltage down and cause the fault. An open in one of the supply circuits should set a position sensor fault against that actuator, not the supply circuit fault.

1. To determine if one of the actuators is causing the fault to be active, disconnect both actuator motor harness connectors. Cycle the ignition off, and back on. If the C2050-1C fault changes to stored, most likely one of the actuators is faulty.
   1. If the fault changed to stored, re-connect the actuator motor harness connectors one at a time while checking for the fault to change back to active. Whichever actuator motor caused the fault to change back to active is faulty and should be replaced in accordance with the service information. The RDM motor and clutch assembly are a matched set used to create the clutch classification and clutch energy specifications. For this reason, the RDM motor should not be replaced separately from the assembly. If the RDM motor is determined to be faulty in any way, the RDM assembly should be replaced.
   2. If the fault remains active when both actuator motors are unplugged, continue to step 2.
2. Connect the negative lead of a DVOM to a good chassis ground. Measure the voltage on the sensor supply circuit at both actuator motor harness connectors.
   1. If the battery voltage is present on either circuit, repair the circuit for a short to voltage.
   2. If battery voltage is not present, continue to step 3
3. Turn the ignition off. Disconnect the DTCM harness connector. Check for continuity between chassis ground and the sensor supply circuit at both actuator motor harness connectors. There should be no continuity to ground.
   1. If there is continuity to ground on either circuit, repair the circuit for a short to ground and retest.
   2. If neither circuit is showing continuity to ground, replace the DTCM in accordance with the service information. With the scan tool, perform the DTCM Replacement procedure in Misc Functions.

MOTOR POSITION SENSOR COMPONENT FAILURE FAULT DIAGNOSTICS (C2060-09, C2070-09):  The position sensor diagnostics contained in this service information apply to both the PTU and RDM sensors.

1. Turn the ignition off. Check the actuator motor harness connector for proper connection at the actuator. Verify that the connector is completely plugged in and properly locked prior to disconnecting for testing. Disconnect the actuator motor harness connector and check for any pushed out, damaged, corroded or spread terminals.
   1. If any damage is found to the connector or terminals, repair the connector and retest.
   2. If the connector and terminals appear in good shape, continue to step 2.
2. Check the DTCM harness connector for proper connection at the module. Verify that the connector is completely plugged in and properly locked prior to disconnecting for testing. Disconnect the DTCM harness connector and check for any pushed out, damaged, corroded or spread terminals.
   1. If any damage is found to the connector or terminals, repair the connector and retest. If the connector is corroded verify that the A/C drain is not plugged causing excessive water accumulation in the A/C condenser housing. If the housing accumulates too much water it can leak on the DTCM harness and connector causing harness damage.
   2. If the connector and terminals appear in good shape, continue to step 3.
3. With both harness connectors unplugged, check both position sensor signal circuits for continuity to either chassis ground or the sensor ground circuit at the actuator harness connector. There should be no continuity to chassis ground or the sensor ground circuit with the circuits isolated.
   1. If a signal circuit shows continuity to chassis ground or the sensor ground circuit, repair the circuit for a short to chassis ground or the sensor ground circuit.
   2. If neither circuit is shorted, continue to step 4.
4. Check for continuity between each position sensor signal circuit and all other circuits at the actuator harness connector. There should be no continuity between the circuits and the other circuit.
   1. If either circuit shows continuity to another circuit, repair the short between the circuits.
   2. If there is no continuity to another circuit, continue to step 5.
5. Measure the resistance of position sensor 1 and position sensor 2 signal circuits and the sensor ground circuit between the actuator motor harness connector and the DTCM harness connector. They should typically have less than 3.0 Ohms.
   1. If any circuit has high resistance repair the circuit and retest.
   2. If both circuits test good, continue to step 6 if testing for the PTU actuator motor fault.
   3. If both circuits test good, continue to step 7 if testing for the RDM actuator motor fault.
6. Replace the actuator motor in accordance with the service information. With the scan tool, erase all DTCs and retest.
   1. If the position sensor DTC returns, replace the DTCM in accordance with the service information.
   2. If the position sensor DTC does not return, repair is complete. Replacing the actuator motor repaired the fault.
7. Replace the DTCM in accordance with the service information. With the scan tool, perform the DTCM Replacement procedure in Misc Functions. Retest the system for faults.
   1. If the position sensor DTC returns, replace the RDM assembly in accordance with the service information.
   2. If the position sensor DTC does not return, repair is complete. Replacing the DTCM repaired the fault.