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Home >> Dodge and Ram >> 2018 >> Charger Pursuit, 5.7L Eng VIN T, 4WD >> Repair and Diagnosis >> Transmission >> Automatic Trans >> (Transmission Control Module (TCM) - Electrical Diagnostics - Nag1 Automatic Transmission) >> DTC Troubleshooting >> P0643-Sensor Reference Voltage 1 Circuit High >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR SPEED SENSOR DTCS 
    1. With the scan tool, check for other transmission DTCs.

      Are there any speed sensor and/or temperature sensor DTCs present?

      Yes 

      • Perform the appropriate diagnostic procedure.

      No 

      • Go To  2
  2. CHECK SOLENOID SUPPLY VOLTAGE ON THE SCAN TOOL 
    1. Start the engine.
    2. With the scan tool, check the Transmission Solenoid Supply Voltage.

      Is the Transmission Solenoid Supply Voltage above 7.2 volts?

      Yes 

      • Go To  3

      No 

      • Go To  5
  3. CHECK (T72) SENSOR SUPPLY CIRCUIT VOLTAGE 
    GC0097937Courtesy of CHRYSLER GROUP, LLC
    1. While back probing, measure the voltage of the (T72) Solenoid Supply Voltage circuit in the TCM harness connector.

      Does the measured voltage match the voltage reading on the scan tool ± 0.2 volts?

      Yes 

      • Go To  4

      No 

      • Using the schematics as a guide, check the Transmission Control Module (TCM) terminals 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 (TCM), REMOVAL .
      • Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to NAG1 TRANSMISSION VERIFICATION TEST  .
  4. (T72) SENSOR SUPPLY VOLTAGE CIRCUIT SHORT TO ANOTHER CIRCUIT 
    GC0097938Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition off to the lock position.
    2. Disconnect the Transmission Electrohydraulic Control Unit Assembly harness connector.
    3. Disconnect all TCM harness connectors.
    4. Measure the resistance between the (T72) Solenoid Supply Voltage circuit and all other circuits in the Transmission Electrohydraulic Control Unit harness connector.

      Is the resistance below 5.0 ohms between the (T72) Solenoid Supply Voltage circuit and all other circuits in the Transmission Electrohydraulic Control Unit Assembly harness connector?

      Yes 

      • Repair the (T72) Solenoid Supply Voltage circuit for a short to another circuit(s).
      • Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to NAG1 TRANSMISSION VERIFICATION TEST  .

      No 

      • Using the schematics as a guide, check the Transmission Control Module (TCM) terminals 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 (TCM), REMOVAL .
      • Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to NAG1 TRANSMISSION VERIFICATION TEST  .
  5. 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 wires while checking for shorted and open circuits.

      Were there any problems found?

      Yes 

      No 

      • Test Complete.