Diagnostic Test

WARNING: This page is about a different car, the 2012 Dodge Durango. However, it is still accessible from the selected car via links, so may be relevant.

CHECK IF THE DTC IS CURRENT
NOTE:
When the Transmission Control Module (TCM) detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set. This information is located in scan tool under Environmental Data. Before erasing any stored DTCs, record any available data to assist in duplicating the conditions in which the DTC originally set.
1. Turn the ignition off to the lock position.
2. With the scan tool, erase Transmission DTCs.
3. Using the Environmental Data recorded earlier, try to duplicate the conditions in which the DTC originally set. It may be necessary to test drive the vehicle.
4. With the scan tool, read Transmission DTCs.
  Did the DTC P0748 reset?
  
  Yes
  - Go To 2.
  No
  - Go To 6.
CHECK THE (T76) MODULATION PRESSURE SOLENOID CONTROL CIRCUIT FOR AN OPEN

Fig 1: Checking Modulation Pressure Solenoid Control Circuit For An Open
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off to the lock position.
2. Disconnect the TCM C2 harness connector.
3. Disconnect the Transmission Electrohydraulic Control Unit Assembly harness connector.
4. Measure the resistance of the (T76) Modulation Pressure Solenoid Control circuit between the TCM C2 harness connector and the Transmission Electrohydraulic Control Unit Assembly harness connector.
  Is the resistance above 5.0 Ohms?
  
  Yes
  - Repair the (T76) Modulation Pressure Solenoid Control circuit for an open.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Go To 3.
CHECK THE (T76) MODULATION PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TO GROUND

Fig 2: Checking Modulation Pressure Solenoid Control Circuit For A Short To Ground
Courtesy of CHRYSLER GROUP, LLC
1. Measure the resistance between ground and the (T76) Modulation Pressure Solenoid Control circuit.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Repair the (T76) Modulation Pressure Solenoid Control circuit for a short to ground.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Go To 4.
CHECK THE (T76) MODULATION PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT

Fig 3: Checking Modulation Pressure Solenoid Control Circuit For A Short To Another Circuit
Courtesy of CHRYSLER GROUP, LLC
1. Measure the resistance between the (T76) Modulation Pressure Solenoid Control circuit and every other circuit in the Transmission Electrohydraulic Control Unit Assembly harness connector.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Repair the (T76) Modulation Pressure Solenoid Control circuit for a short to another circuit.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Go To 5.
CHECK THE MODULATING PRESSURE CONTROL SOLENOID VALVE

Fig 4: Checking Modulating Pressure Control Solenoid Valve Resistance
Courtesy of CHRYSLER GROUP, LLC
1. Reconnect the Transmission Electrohydraulic Control Unit Assembly harness connector.
3. Measure the resistance between the (T76) Modulation Pressure Solenoid Control circuit and the (T78) Solenoid Supply Voltage circuit in the TCM C2 harness connector.
  Is the resistance between 2.5 and 6.5 Ohms?
  
  Yes
  - Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM in accordance with the Service Information. Refer to MODULE, TRANSMISSION CONTROL, REMOVAL .
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Replace the Modulating Pressure Control Solenoid Valve in accordance with the Service Information. Refer to UNIT, ELECTROHYDRAULIC CONTROL, REMOVAL .
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wiring and connectors while checking for any possible open or shorted circuits.
4. Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.
  Were there any problems found?
  
  Yes
  - Repair as necessary.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Test Complete.