Diagnostic Test - RDM Actuator Motor

TECH TIPS: 

• The RDM actuator motor has a limited range of rotational travel when the system and internal components are mechanically sound. The RDM actuator motor can be applied to any position between the fully engaged and fully disengaged stops to apply varied pressure to the torque transfer clutch. The DTCM monitors the rotation of the shaft using the two hall effect sensor signals inside the motor to determine if the motor reaches the correct position that is being commanded. Most of the motor performance diagnostics covered below will set if the motor is unable to rotate to the proper position, or a mechanical failure causes the motor to go beyond the mechanical stop and free spin.
• 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.
• Refer to the DTCM Verification Test service 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. 

OVERTEMP DIAGNOSTICS FOR THE RDM ACTUATOR AND CLUTCH (C2100-98, C2150-98, C221D-98, C2230-98):  If there are any other system faults in the PTU or RDM systems, diagnose the other faults with the PTU or RDM systems. Typically, an issue with one of the assemblies that is causing improper shifting and overworking the system will set other system performance DTCs. If the system only has an overtemp fault, this condition may not require a repair action to correct since the system can set an overtemp fault during extreme use. If the C2100-98 or C2230-98 fault is set alone, it is typically caused by overworking the system. If the more severe DTC C221D-98 is also set, it would indicate that there is likely a system failure with the assembly. Verify the following items before clearing an overtemp fault and returning to the customer.

1. Verify the fluid level and type are correct.
   1. If the fluid is low or appears to be incorrect, top off or change the fluid and retest the system for proper operation. If the fluid is low, perform a visual inspection and repair any leaks found.
   2. If the fluid is full and appears ok, continue testing is step 2.
2. Test drive the vehicle in Auto mode and listen for any grinding or clashing when the PTU is switching modes. This could occur if the propeller shaft is not coming up to speed due to an issue with the RDM clutch, or mechanical issues in the PTU (worn or damaged collar or shaft splines).
   1. If the system appears to be operating and shifting normally, no abnormal noises are heard and the fault does not return, no repair is likely needed, Return the vehicle to the customer and advise that the issue may have been caused by overworking the system.
   2. If the system appears to be operating and shifting normally, but the fault returns, continue to step 3.
   3. If the system is not shifting properly, or is clashing when engaging AWD, replace the RDM in accordance with the service information
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 onto the DTCM harness and connector causing harness damage.
   2. If the connector and terminals appear in good shape, continue to step 4.
4. Disconnect the RDM actuator motor harness connector. Check for continuity between ground and both RDM actuator motor control circuits. There should be no continuity with the circuits isolated.
   1. If either circuit is shorted to ground, repair the short. Reconnect the harness connectors and retest.
   2. If the circuits are not shorted to ground, continue to step 5.
5. Replace the DTCM in accordance with the service information. Reconnect the harness connectors. Erase all DTCs and test drive the vehicle. With the scan tool verify that no overtemp DTCs returned.
   1. If the DTC does not return, replacing the DTCM repaired the fault.
   2. If the DTC returns, replace the RDM assembly in accordance with the service information.

ACTUATOR MOTOR CONTROL CIRCUIT COMPLETE CIRCUIT DIAGNOSTICS - RDM (C2100-13/14/15, C2160-04): 

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 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 resistance of the actuator motor internal control circuit by measuring the resistance across the motor control pins at the actuator motor. Measure at the actuator motor terminals, not the harness connector. The resistance should be less than 5.0 Ohms.
   1. If the actuator motor has high resistance, replace the RDM assembly in accordance with the service information.
   2. If the actuator motor internal resistance tested good, continue to step 3.
3. Check the actuator motor for an internal short. Measure the resistance between the motor case and both motor control terminals at the actuator motor. There should be no continuity between the motor control circuits and the motor case.
   1. If the actuator motor has an internal short to the motor case, replace the RDM assembly in accordance with the service information.
   2. If the actuator motor is not internally shorted to the motor case, continue to step 4.
4. Turn the ignition on and measure the voltage on both motor control circuits at the actuator motor harness connector.
   1. If the voltage on either circuit is equal to battery voltage, repair the circuit for a short to voltage.
   2. If battery voltage is not present on either circuit, continue to step 5.
5. 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 onto the DTCM harness and connector causing harness damage.
   2. If the connector and terminals appear in good shape, continue to step 6.
6. Check for continuity between the motor control circuits. There should be no continuity between the circuits when isolated.
   1. If there is continuity between the circuits, repair the short between the motor control circuits.
   2. If the circuits are not shorted together, continue to step 7.
7. Check for continuity between ground and both of the motor control circuits. There should be no continuity to ground with the circuits isolated.
   1. If either circuit has continuity to ground, repair the circuit for a short to ground.
   2. If neither circuit is shorted to ground, continue to step 8.
8. Measure the resistance of actuator motor (+) control and motor (-) control circuits between the actuator motor harness connector and the DTCM harness connector. They should typically have less than 3.0 Ohms.
   1. If either circuit has high resistance repair the circuit and retest.
   2. If both circuits test good, replace the DTCM in accordance with the service information.

ACTUATOR MOTOR SYSTEM PERFORMANCE FAULT DIAGNOSTICS - RDM (C2080-64, C2160-04, C2210-92, C2250-78):  Perform the diagnostics for any actuator motor control circuit faults or position sensor faults before performing the performance fault diagnostic.

1. 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 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. Verify that the actuator motor control circuits are pinned correctly at the actuator motor and DTCM harness connectors.
   1. If the pins are switched at either connector, correct the wiring and retest.
   2. If the circuits are pinned correctly, continue to step 3.
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 onto the DTCM harness and connector causing harness damage.
   2. If the connector and terminals appear in good shape, continue to step 4.
4. Disconnect the actuator motor harness connector. Check the actuator motor circuits for high resistance by measuring the resistance of the actuator motor (+) control and motor (-) control circuits between the actuator motor harness connector and the DTCM harness connector. They should typically have less than 3.0 Ohms.
   1. If either circuit has high resistance repair the circuit and retest.
   2. If both circuits test good, replace RDM the assembly in accordance with the service information.

ACTUATOR MOTOR SYSTEM PERFORMANCE (FREE SPINNING) FAULT DIAGNOSTICS - RDM (C2240-92): 

1. Verify that the actuator motor is mounted correctly on the RDM assembly.
   1. If the actuator motor is found to be loose or incorrectly mounted, mount the actuator motor on the assembly correctly and retest.
   2. If the actuator motor is mounted correctly, replace RDM the assembly in accordance with the service information.

RDM CLASSIFICATION NOT LEARNED FAULT DIAGNOSTICS - (C2300-00):  The RDM classification is either not programmed in the DTCM or is incorrect. This must be learned if the DTCM or RDM are replaced.

1. The RDM classification info is stamped on the RDM. Using the scan tool, verify that the RDM classification parameter stamped on the RDM matches what is stored in the DTCM.
   1. If the parameters do not match, program the correct RDM classification into the DTCM. Erase DTC, cycle the ignition and verify repair.
   2. If parameters match, continue to step 2.
2. Check for any DTCM software updates.
   1. If updates are available, perform the software update. Erase DTC, cycle the ignition and verify repair. If the DTC returns, replace the DTCM in accordance with the service information.
   2. If there are no updates available, replace the DTCM in accordance with the service information.