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Home >> Jeep >> 2018 >> Grand Cherokee Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 29 (8HP70 Automatic Transmission - DTCS P0219-00 To P1D92-00) >> DTC Troubleshooting >> P0721-00-Output Shaft Speed Sensor Circuit Performance >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR AN ACTIVE CONDITION 
    1. Turn the ignition on.
    2. With the scan tool, erase Transmission Control Module (TCM) Diagnostic Trouble Codes (DTCs).
    3. Raise the vehicle on the hoist.
    4. Start the Engine.
    5. With the scan tool, monitor the Output Speed Sensor RPM.
    6. Firmly apply the brake pedal and place the gear selector in Drive.
      WARNING:

      To avoid personal injury or death, keep hands and feet clear of rotating wheels.

    7. Release the brakes and raise the engine speed to allow the Transmission to perform a 2-3 and 3-4 upshift.

      Did the Output Speed Sensor display an engine speed above 1, 000 RPM?

      Yes 

      • Go To  2

      No 

      • Using the schematics as a guide, check the Transmission Control Module (TCM) connector and all related in-line connector terminals for corrosion, damage, or pushed out terminals. Pay particular attention to the power and ground circuits. If no problems are found, replace and program the TCM in accordance with the Service Information. Refer to MODULE PROGRAMMING
      • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .
  2. CHECK TRANSMISSION FOR INTERNAL FAILURE 
    NOTE:

    This DTC is an indication of a internal Transmission failure. It can also be set due to an improper or aborted transfer case shift, I.E. if the system thinks the transfer case is in high range when it is actually in low range. Any condition mechanical or hydraulic which causes the actual input and output speed ratios to not match the expected ratio.

    1. Remove the Transmission Oil Pan and inspect for excessive debris such as clutch friction material or metal contamination.

      Is there any indication of an internal Transmission failure?

      Yes 

      • Repair internal Transmission as necessary in accordance with the Service Information.
      • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

      No 

      • Using the schematics as a guide, check the Transmission Control Module (TCM) connector and all related in-line connector terminals for corrosion, damage, or pushed out terminals. Pay particular attention to the power and ground circuits. If no problems are found, replace and program the TCM in accordance with the Service Information. Refer to MODULE PROGRAMMING
      • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .
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