GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The powertrain control module (PCM) monitors the following conditions:

    • The transmission output speed
    • The engine speed

The PCM compares the engine speed with the output speed sensor.

Conditions for Setting the DTC

    • With the "4WD LOW" switch OFF,
    • No output speed sensor signal is inputted while the engine is running at higher than specified engine speed with the transmission in Drive.
    • One driving cycle detection logic

Action Taken When the DTC Sets

    • DTC P0722 stores.
    • The malfunction indicator lamp (MIL) turns ON.

Diagnostic Aids

Inspect for the following conditions:

    • The output speed sensor.
    • The PCM and related wiring.

If DTC P0722 cannot duplicate, the information included in the Freeze Frame data may be useful in determining the vehicle operating conditions when the DTC set.

DTC Confirmation Procedure

  1. Turn the ignition switch to the LOCK position.
  2. Connect the scan tool to the data link connector (DLC).
  3. Turn the ignition switch ON.
  4. Use the scan tool in order to clear the following items:
  5. • DTC P0722
    • Any pending DTCs
  6. Start the engine.
  7. Warm the engine up to normal operating conditions.
  8. If equipped, shift the transfer case lever to 2H.
  9. Operate the vehicle under all the following conditions:
  10. Drive the vehicle at 40 km/h (25 mph) or more for 10 seconds.
  11. Stop the vehicle.
  12. Use the scan tool in order to test for a pending DTC.

Test Description

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

  1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. The scan tool creates an electronic copy of the data taken when the fault occurred. The information then stores in the scan tool for later reference.

  2. This step tests for output sensor resistance.

  3. This step checks for sensor damage.

Step

Action

Value(s)

Yes

No

1

Was the On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 1.6L, Diagnostic System Check - Engine Controls in Engine Controls - 2.0L or Diagnostic System Check - Engine Controls in Engine Controls - 2.5L

2

  1. Install a scan tool.
  2. Turn the ignition to ON, leaving the engine OFF.
  3. Perform the scan tool Clear DTC Information function.
  4. Operate the vehicle within the Freeze Frame conditions as observed.

Does the scan tool display any other DTCs in addition to DTC P0722?

--

Go to the applicable DTC table

Go to Step 3

3

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the PCM connector C3.
  3. Check the output speed sensor resistance.

Is the resistance within the specified range?

387-473  ohms

Go to Step 7

Go to Step 4

4

Inspect all of the electrical connections for poor terminal contact or a poor connection.

Does poor terminal contact or poor connections exist?

--

Go to Step 11

Go to Step 5

5

Check wiring for an open or short to ground. Refer to Circuit Testing in Wiring Systems.

Is the repair complete?

--

Go to Step 9

Go to Step 6

6

Replace output speed sensor.

Is the procedure complete?

--

Go to Step 9

--

7

  1. Install a known-good PCM. Refer to Powertrain Control Module Replacement in Engine Controls-2.0L or Powertrain Control Module Replacement in Engine Controls-2.5L.
  2. Perform the DTC Confirmation Procedure.

Does DTC P0722 reset?

--

Go to Step 8

Go to Step 9

8

Visually check the sensor and overdrive clutch drum for damage or foreign material.

Is damage or foreign material present?

--

Go to Step 11

Go to Diagnostic Aids for a possible intermittent condition

9

If OK, replace the PCM.

Is the procedure complete?

--

Go to Step 10

--

10

  1. Turn the ignition switch to the LOCK position.
  2. Connect all the connectors.
  3. Perform the DTC Confirmation Procedure.

Does the scan tool display any DTCs?

--

Go to the applicable DTC table

System OK

11

Repair as necessary.

Is the system operating properly?

--

System OK

Go to Step 2