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Home >> Jeep >> 2009 >> Commander Overland, RWD >> Repair and Diagnosis >> Transmission >> Automatic Trans >> (Powertrain Control Module (Pcm) - Electrical Diagnostics - 545RFE Automatic Transmission) >> DTC Troubleshooting >> P0734-Gear Ratio Error In 4TH >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR RELATED DTCS 
    1. With the scan tool, check for other transmission DTCs
    2. If any of these DTCs are present, perform their respective tests first.

      Are there any Transmission solenoid, line pressure, speed sensor, and/or loss of prime DTCs present?

      Yes 

      No 

      • Go to step  2
  2. CHECK EVENT DATA 
    1. With the scan tool, read and record the Event Data.
      NOTE: Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.

      Does the Event Data display information for the DTC P0734?

      Yes 

      • Go to step  4

      No 

      • Go to step  3
  3. CHECK FOR ANOTHER DTC 

    In the Event Data recorded earlier, does the Event Data show the DTC P1790, with Target Gear = 4th, or with both the 4C and OD clutches applying?

    Yes 

    • Go to step  4

    No 

    • Go to step  6
  4. CHECK INPUT RPM 

    In the Event Data recorded earlier, does the Input RPM read zero?

    Yes 

    No 

    • Go to step  5
  5. CHECK LINE PRESSURE READING 

    In the Event Data recorded earlier, is the line pressure reading more than 10 PSI below the desired line pressure reading?

    Yes 

    • Remove the Transmission Oil pan and check the Transmission Oil filter for improper installation or plugged, if Primary oil filter is OK, check the main regulator valve in pump. If excessive debris is in the oil pan, check clutches and repair as necessary. Refer to the appropriate Service Information for proper repair procedures.
    • Perform the 545RFE TRANSMISSION VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .

    No 

    • Go to step  6
  6. CHECK TRANSMISSION FOR SLIPPAGE 
    1. Erase DTCs and road test the vehicle.
    2. Check the transmission operation in reverse and all forward gears.

      During the road test, was there any obvious slippage noted in 4th gear or a runaway during the 3-4 shift?

      Yes 

      • Go to step  8

      No 

      • Go to step  7
  7. CHECK IF DTC RESETS 
    1. With the scan tool, check for Transmission DTCs after the road test.

      Did the DTC P0734 reset?

      Yes 

      • Go to step  8

      No 

      • Test Complete.
  8. CHECK INTERNAL TRANSMISSION 
    1. Remove the Transmission Oil Pan and Valve Body in accordance with the Service Information and check for the following:
      • Excessive debris in the oil pan.
      • Remove the Valve Body and check if the accumulator cover is intact and the 4C tower seal is not cut or split.
      • OD and 4C accumulator pistons for cracks and/or cut seals.
      • Solenoid Switch Valve and its plugs for stickiness or wear.
      • Cut or missing No. 5 and/or No. 6 check ball.
      • OD bleed orifice on top of the Valve Body
      • Air check the OD and 4C hydraulic clutch circuits for excessive leakage. Refer to the appropriate Service Information.
      NOTE: Both the OD and 4C hydraulic clutch circuits contain a small bleed orifice. A small amount of air leakage is considered normal. The OD hydraulic clutch circuit bleed orifice connects to the Reverse input clutch hydraulic cavity. A small amount of air leakage into the Reverse hydraulic clutch circuit is considered normal.

      Were there any problems found?

      Yes 

      • Repair as necessary. Refer to the appropriate Service Information for proper repair procedures.
        NOTE: If the OD or 4C clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
      • Perform the 545RFE TRANSMISSION VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .

      No 

      • Go to step  9
  9. CHECK REVERSE GEAR 

    Was there no reverse gear during the road test?

    Yes (no reverse) 

    • Go to step  10

    No (reverse gear OK) 

  10. CHECK ROAD TEST RESULTS 

    During the road test, was there no 2nd gear and no 4th gear, but 3rd gear (limp-in) was OK?

    Yes 

    • Go To  11

    No 

    • Go To  12
  11. CHECK FOR BROKEN REVERSE SUN GEAR WELD 
    1. Working through the windows in the bottom of the case, check for a broken Reverse Sun gear weld to the reaction carrier as follows:
      1. Hold the Transmission Output Shaft by holding the Transmission Manual Lever in the park position.
      2. Rotate the Input Annulus gear and drive shell (the drum that encloses the two rearmost carriers).
      3. Check to see if the reaction carrier (the front most carrier, whose outer shell is splined to the 2C clutch) is rotating faster than the drive shell is being turned.

      Is the reaction carrier turning faster than the drive shell?

      Yes 

      No 

  12. CHECK REVERSE CARRIER HUB WELD 
    1. Remove the Transmission in accordance with the Service Information and inspect the weld on the reverse carrier hub.

      Were there any problems found?

      Yes 

      No 

      • Disassemble and inspect the input clutch assembly. Check the OD and Reverse clutch seals, discs, and bleed orifice (in the OD/Reverse clutch piston). Check the OD hub and shaft. Repair as necessary. Refer to the appropriate Service Information for proper repair procedures.
      • Perform the 545RFE TRANSMISSION VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
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