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Test Description

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The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step tests ignition voltage.
  2. 3:  This step tests the wiring at the TCM.
  3. 4:  This step tests for proper resistance at the output speed sensor resistance.
DTC P0721

Step Action Value Yes No
Schematic Reference: Automatic Transmission Controls Schematics
1 Did you perform the Diagnostic System Check - Automatic Transmission? - Go to Step 2  Go to Diagnostic System Check - Automatic Transmission
2 
  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.
    3. IMPORTANT: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data.
  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Using the scan tool, observe ignition voltage.
Is the voltage within the specified range?		 9-18 V Go to Step 3  Go to DTC P0562  for low voltage or DTC P0563  for high voltage
3 
  1. Turn the ignition OFF.
  2. Disconnect the C2 connector (RED) from the TCM.
  3. Install the J 39700  breakout box and the J 43799  breakout box adapter at C2 connector.
  4. Using a DMM, measure the resistance between connector C2 terminals 15 and 16.
Is the speed sensor resistance within the specified values?		 2,600 ohm @ 25°C (77°F) Go to Diagnostic Aids Go to Step 4 
4 
  1. Disconnect the wiring harness from the output speed sensor.
  2. Using a DMM, measure the resistance between the speed sensor terminals.
Is the speed sensor resistance within the specified values?		 2,600 ohm @ 25°C (77°F) Go to Step 5  Go to Step 6 
5 Repair the engine wiring harness. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 7  -
6
IMPORTANT: Do not rotate the speed sensor in the retaining bracket. Orientation is fixed, and if changed, may cause improper operation.
Replace the output speed sensor. Refer to Speed Sensor Replacement .Did you complete the replacement?		 - Go to Step 7  -
7 Perform the following procedure in order to verify the repair:
  1. Clear the DTC.
  2. Using the scan tool, monitor the output speed sensor operation.
  3. Select Specific DTC.
  4. Enter DTC P0721.

Has the test run and passed?		 - System OK Go to Step 1 
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