GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Lucerne 🢒 DTC 🢒 DTC P0722

Object Number: 1650962 Size: SF
Master Electrical Component List
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Control Module References

Circuit Description

The vehicle speed sensor (VSS) is a permanent magnet generator attached to the transmission case. The final drive assembly has a toothed wheel, VSS rotor. As the final drive assembly rotates, an AC voltage is induced and transmitted to the transmission control module (TCM). The TCM converts the AC voltage into a digital signal. The TCM uses the vehicle speed to determine shift timing, torque converter clutch apply and release, and gear ratio.

If the TCM detects a low vehicle speed and a high transmission input shaft speed while in a drive range, then DTC P0722 sets. DTC P0722 is a type B DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0722 Output Speed Sensor Circuit Low Voltage

Conditions for Running the DTC
    • No MAF DTCs P0101, P0102 or P0103.
    • No MAP DTCs P0106, P0107 or P0108.
    • No TP DTCs P0121, P0122 or P0123.
    • No OSS DTC P0723.
    • No AT ISS DTCs P0716 or P0717.
    • The engine run time is greater than 5 seconds.
    • The transmission is not in PARK or NEUTRAL.
    • The TP angle is 8 percent or greater.
    • The transmission input shaft speed is 1,000-5,000 RPM.
    • Trans. Temp. is -40°C (-40°F) or greater.
    • TCC slip speed is -20 RPM or greater.

Conditions for Setting the DTC
    • The engine torque is 50-1492 N·m (37-1100 lb ft) in D4.
    • The engine torque is 1492 N·m (1100 lb ft) in Park/Neutral.
    • LD8: The transmission output shaft speed is 200 RPM or less for 3 seconds.
    • L37: The transmission output shaft speed is 239 RPM or less for 3 seconds.

Action Taken When the DTC Sets
    • The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
    • The TCM commands maximum line pressure.
    • The TCM freezes transmission adaptive functions.
    • The TCM calculates vehicle speed from the automatic transmission input, shaft, speed sensor and commanded gear.
    • The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records and the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
    • The TCM stores DTC P0722 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC
    • The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
    • The TCM clears the DIC message when the condition no longer exists.
    • A scan tool can clear the MIL/DTC.
    • The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
    • The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Test Description

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

  1. This step tests for DTCs and for a vehicle speed signal. It is important to record Freeze Frame and Failure Record information before proceeding further.

    2.

  2. This step tests for a resistance value greater than 1,911 ohms which would indicate an open in the high signal circuit, the low signal circuit or the VSS.

DTC P0722

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a 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. Using the Clear Info function erases the Freeze Frame and Failure Records from the TCM.

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.

    5. Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

  5. Raise and support the drive wheels.
  6. Start and idle the engine.
  7. Place the transmission in DRIVE.
  8. Select Transmission OSS on the scan tool.

With the drive wheels rotating, does the Transmission OSS RPM increase when the wheel speed increases?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the TCM.
  3. Using the J 35616 GM Terminal Test Kit, connect the DMM between TCM terminals VSS high and VSS low signal circuits.
  4. Select AC volts on the DMM.

    5. Important: Place the gear select lever in the Neutral position before rotating the drive wheel.

  5. Rotate the right front drive wheel by hand.
  6. Observe the DMM display.

Can a voltage greater than the specified value be obtained?

0.5 V AC

Go to Step 14

Go to Step 4

4
  1. Leave the DMM test leads connected.
  2. Measure circuit resistance.

Does the resistance measure within the specified range?

1,260-1,911 ohms

Go to Step 8

Go to Step 5

5

Does the resistance measure greater than the specified value?

1,911 ohms

Go to Step 11

Go to Step 6

6
  1. Leave the DMM test leads connected.
  2. Disconnect the VSS connector at the transmission.

Does the resistance measure less than the specified value?

1,260 ohms

Go to Step 7

Go to Step 13

7

Test the high signal circuit and the low signal circuit of the VSS for being shorted together.

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 15

--

8

Test the high signal circuit of the VSS for a short to ground.

Refer to Testing for Short to Ground and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 15

Go to Step 9

9
  1. Connect the TCM.
  2. Using the J 35616 , connect the DMM test leads to the VSS wiring harness connector end.
  3. Select DC volts on the DMM.
  4. Turn ON the ignition, with the engine OFF.

Does the DMM display system voltage?

--

Go to Step 10

Go to Step 12

10

Test the high signal circuit of the VSS for a short to voltage.

Refer to Testing for a Short to Voltage and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 15

--

11
  1. Test the high signal circuit of the VSS for an open.
  2. Test the low signal circuit of the VSS for an open.

Refer to Testing for Continuity and Wiring Repairs .

Did you find and correct a condition?

--

Go to Step 15

Go to Step 13

12
  1. Remove the VSS.

    2. Refer to Vehicle Speed Sensor Replacement .

  2. Inspect the VSS and the transmission for the following conditions:
    3. • Incorrect VSS
    • VSS damage
    • Excessive VSS to speed sensor rotor gap
    • Incorrect speed sensor rotor alignment
    • Speed sensor rotor damage
  3. Repair any of the above conditions as necessary.

Refer to Differential Carrier and Housing Removal .

Did you complete the repair?

--

Go to Step 15

--

13

Replace the VSS.

Refer to Vehicle Speed Sensor Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the TCM.

Refer to Control Module References .

Did you complete the replacement?

--

Go to Step 15

--

15

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle in order to achieve a Transmission OSS of greater than 500 RPM for LD8 and 597 RPM for L37 for 3 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0722.

Has the test run and passed?

--

Go to Step 16

Go to Step 2

16

With the scan tool, observe the stored information, capture info. and DTC info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK