Power Transfer Unit (PTU) And Rear Drive Module (RDM) Systems - Temperature 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. 

COMPLETE CIRCUIT DIAGNOSTICS USING A DVOM - PTU (C2090-09) OR RDM (C2080-09):  On most vehicles the temp sensor voltage data reading is not available in the scan tool and the DTCM does not set individual low/high faults for the temperature sensors. Therefore the entire circuit path must be checked for opens and shorts with a temp sensor component failure fault.

1. Check the actuator 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. Disconnect the actuator motor harness connector. Turn the ignition on. Measure the voltage on the actuator motor temp signal circuit at the actuator motor harness connector.
   1. If the signal voltage measures above 6.0 volts it would indicate that the signal circuit is shorted to another voltage supply. Repair the circuit for a short to voltage.
   2. If the signal voltage measures 0.0 volts, continue to step 3.
   3. If the signal voltage measures 5.0 volts, continue to step 6.
3. Turn the ignition off. 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 4.
4. Check the actuator motor temp signal circuit for continuity to both chassis ground and both sensor ground circuits. There should be no continuity with the circuits isolated.
   1. If there is continuity to chassis ground and either sensor ground circuit, repair the actuator motor temp signal circuit for a short to chassis ground or the sensor ground circuit.
   2. If the actuator motor temp signal circuit is not shorted to chassis ground or the either sensor ground circuit, continue to step 5.
5. Check the actuator motor temp signal circuit for an open circuit between the actuator motor harness connector and DTCM harness connector. Typically, there should be less than 3.0 Ohms of resistance in the circuit.
   1. If the circuit is open, repair the circuit and retest.
   2. If the circuit checks good, the DTCM is likely faulty. Before condemning the DTCM, use the wiring information to identify and check all related harness connectors for pushed out, spread, corroded or dirty terminals before condemning the DTCM. If no issues are found, replace the DTCM in accordance with the service information.
6. Turn the ignition off. 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 7.
7. Measure the resistance of the actuator motor temp signal circuit between the actuator motor harness connector and DTCM harness connector. Typically, it should be less than 3.0 Ohms.
   1. If the resistance is high, repair the circuit and retest.
   2. If the circuit checks good, continue to step 8.
8. Measure the resistance of the actuator motor temp sensor ground circuit between the actuator motor harness connector and DTCM harness connector. Typically, it should be less than 3.0 Ohms.
   • If the resistance is high, repair the circuit and retest.
   • If the circuit checks good, continue to step 9.
9. To check the temp sensor inside the actuator motor, reconnect the DTCM and actuator motor harness connector. Turn the ignition on. Back probe and measure the voltage at the actuator motor temp signal and temp sensor ground circuits at the actuator motor harness connector.
   1. If the signal voltage is measuring between 0.2v and 4.8v, the actuator motor temp signal is a logical reading. There may have been an intermittent connection in one of the harness connectors. Use the wiring information to identify and check all related harness connectors for pushed out, spread, corroded or dirty terminals before condemning the DTCM. If no issues are found, replace the DTCM in accordance with the service information. If the circuit fault is active with a normal sensor reading, the DTCM is likely faulty.
   2. If the signal circuit measures 5v and the temp sensor ground circuit measures 0v, the actuator motor is likely faulty. For the PTU, replace the actuator motor in accordance with the service information. The RDM actuator 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.
   3. If the temp sensor ground circuit measures 5v, and the ground was not open when tested, the sensor ground inside DTCM is likely faulty. Before condemning the DTCM, use the wiring information to identify and check all related harness connectors for pushed out, spread, corroded or dirty terminals before condemning the DTCM. If no issues are found, replace the DTCM in accordance with the service information.