Circuit Description
The output shaft speed sensor assembly (VSS assembly) provides vehicle speed information to the transmission control module (TCM). The VSS assembly is a permanent magnet generator consisting of a toothed rotor mounted on the output shaft and the VSS. The generator produces a pulsing AC voltage as the rotor teeth pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The TCM converts the pulsing voltage to vehicle speed. The TCM uses the output shaft speed signal to determine shift timing and torque converter clutch (TCC) scheduling.
If the TCM detects no vehicle speed when there is engine speed in a drive gear range, then DTC P0722 sets. DTC P0722 is a type B DTC.
Conditions for Running the DTC
| • | The transmission is not in Park, Reverse, Neutral or undefined. |
| • | The engine speed is greater than 3008 RPM. |
Condition for Setting the DTC
The transmission output speed is 0 RPM.
Action Taken When the DTC Sets
| • | The TCM flashes the sport mode lamp and sends a MIL request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL. |
| • | The ECM records the operating conditions in the Freeze Frame at the time of the MIL request from the TCM. |
| • | The transmission operates in the default mode (maximum line pressure, command 4th gear, inhibit TCC, freeze shift adapts). |
Conditions For Clearing the MIL/DTC
| • | The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL request. |
| • | A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic. |
| • | The scan tool clears the MIL/DTC. |
| • | The TCM cancels the DTC default mode 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.
-
Disable the traction control system when performing this step.
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This step tests the VSS assembly circuit.
-
This step tests the integrity of the VSS assembly.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission ? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission | |
Important: Record the Failure Records before clearing the DTCs. Using the Clear Info function erases the Failure Records from the ECM and the TCM. 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. With the drive wheels rotating, does the Scan Tool Transmission OSS increase with the drive wheel speed? | -- | Go to Intermittent Conditions in Engine Controls | ||
|
Caution: When you are performing service on or near the SIR components or the SIR wiring, you must disable the SIR system. Refer to Disabling the SIR System. Failure to follow the correct procedure could cause air bag deployment, personal injury, or unnecessary SIR system repairs.
Is the resistance within the specified range? | 2750-3770 ohms | |||
4 | Measure the resistance from terminal 42 to a known good ground. Is the resistance greater than the specified value? | 50 K ohms | ||
By vigorously rotating the wheel by hand, can a voltage greater than the specified value be obtained? | 0.5 V AC | |||
6 |
Is the resistance within the specified range? | 2750-3770 ohms | ||
7 | Inspect the OSS LO and OSS HI circuits (CKTs FB 703 (BLK/YEL) and PU 705 (BLU/GRN) for a short to ground. Refer to Testing for Short to Ground in Wiring Systems. Did you find the condition? | -- | Go to Intermittent Conditions in Engine Controls | |
8 | Inspect the OSS LO and OSS HI circuits (CKTs FB 703 (BLK/YEL) and PU 705 (BLU/GRN) for an open circuit. Refer to Testing for Continuity in Wiring Systems. Did you find the condition? | -- | Go to Intermittent Conditions in Engine Controls | |
9 | Make the necessary wiring repairs. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
10 | Repair or replace the VSS Reluctor Wheel. Refer to Case Extension and Gasket Replacement . Is the action complete? | -- | -- | |
11 |
Did you find a condition? | -- | ||
12 | Replace the VSS. Refer to Vehicle Speed Sensor Replacement . Is the action complete? | -- | -- | |
13 | Replace the TCM. Refer to Transmission Control Module Replacement . Is the action complete? | -- | -- | |
14 | Perform the following procedure in order to verify the repair:
Does the Scan Tool display transmission output speed? | -- | System OK |
