LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Dodge and Ram >> 2013 >> Challenger SXT >> Repair and Diagnosis >> Transmission >> Transmission Control Systems >> (Transmission Control Module (TCM) - Electrical Diagnostics) >> DTC Troubleshooting >> P0731-Gear Ratio Error In 1ST >> Diagnostic Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Test

  1. CHECK IF THE PINION FACTOR IS PROGRAMMED 
    1. With the scan tool, check if the pinion factor has been programmed in the FCM.
      NOTE:

      If the Pinion Factor is not properly programmed, a Gear Ratio DTC may set.

      Was the Pinion Factor properly programmed for the actual tire size and axle ratio of the vehicle?

      Yes 

      • Go to step  2

      No 

      • With the scan tool, properly program the Pinion Factor in the TIPM.
      • Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  2. CHECK FOR OTHER TRANSMISSION DTCS 
    1. With the scan tool, check transmission DTCs.

      Are there any solenoid and/or solenoid supply voltage DTCs present?

      Yes 

      • Refer to the Transmission DTC based Diagnostics and perform the appropriate diagnostic procedure.

      No 

      • Go to step  3
  3. CHECK TRANSMISSION FLUID LEVEL 
    NOTE:

    Low fluid level can be the cause of many transmission problems. Visually inspect the transmission and cooler lines for leakage and repair as necessary and adjust the fluid level in accordance with the Service Information. If no visual leaks are observed and the vehicle has obtained over 1610 km (1000 miles) from either new or transmission service, a fluid level check is unnecessary.

    1. Check the transmission fluid level and condition in accordance with the Service Information.

      Is the fluid level correct?

      Yes 

      • Go to step  4

      No 

      • Properly adjust the fluid level in accordance with the Service Information.
      • Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  4. CHECK IF DTC IS CURRENT 
    1. With the scan tool, record the Environmental Data and erase Transmission DTCs.
      NOTE:

      If the TCM detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set and 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.

    2. Using the Environmental Data recorded earlier, test drive the vehicle while trying to duplicate the conditions in which the DTC originally set.

      Did the DTC P0731-GEAR RATIO ERROR IN 1ST reset?

      Yes 

      • Repair internal transmission as necessary in accordance with the Service Information. Pay particular attention to components related to the referenced DTC.
      • Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go to step  5
  5. INTERMITTENT 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.
      • Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Test Complete.
scientia non olet · About LEMON Manuals