Circuit Description
The automatic transmission output speed sensor (AT OSS) assembly provides vehicle speed information to the transmission control module (TCM). The OSS sensor assembly is a hall-effect sensor. The sensor is mounted in the transmission case facing the parking lock gear which is splined to the output shaft assembly. As the output shaft and parking lock gear rotate, the toothed parking lock gear produces a square wave voltage signal as the teeth pass through the magnetic field of the sensor. The number of pulses increases as the speed of the vehicle increases. The TCM converts the 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 A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0722 Output Speed Sensor Circuit Low Voltage
Conditions for Running the DTC
Fail Case 1
| • | No TR Switch DTC P0705. |
| • | No transmission fluid temperature (TFT) DTCs P0711, P0712, or P0713. |
| • | No ISS DTC P0717. |
| • | The ignition voltage is 10.5-18 volts. |
| • | Vehicle speed is 66 km/h (41 mph). |
| • | Trans. Protection Mode is OFF. |
| • | The calculated AT OSS is 1,000 RPM or greater. |
| • | The transmission is not shifting. |
| • | If the transmission temperature is greater than 20°C (68°F), the TR Switch has been DRIVE for 2.5 seconds or greater. |
| • | If the transmission temperature is 0-20°C (32-68°F), the TR Switch has been DRIVE for 10 seconds or greater. |
| • | If the transmission temperature is less than 0°C (32°F), the TR Switch has been DRIVE for 3 minutes or greater. |
Fail Case 2
| • | The ignition voltage is 10.5-18 volts. |
| • | Trans. Protection Mode is OFF. |
| • | The engine is running. |
Conditions for Setting the DTC
Fail Case 1
The TCM does not detect any pulses from the OSS and there are 6,000 pulses from the ISS.
Fail Case 2
The OSS signal circuit is open or shorted for 30 seconds or greater.
Action Taken When the DTC Sets
| • | The TCM requests the powertrain control module (PCM) to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM turns the Trans. Protection Mode ON. |
| • | The transmission will operate in 5th gear when the transmission is shifted into D or I range and 2nd gear when shifted into L range. |
| • | The line pressure is at maximum. |
| • | The torque converter clutch (TCC) is disabled. |
| • | The TCM freezes the transmission adaptive functions. |
| • | The TCM calculates the output speed based on the input speed. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
| • | The TCM stores DTC P0722 in TCM history. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | 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 is OFF long enough in order to power down the TCM. |
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||
2 |
Notice: In order to avoid damage to the drive axles, support the lower control arms in the normal horizontal position. Do not run the vehicle in gear with the wheels hanging down at full travel.
Important:
Does the scan tool display a steady transmission output speed above the specified value? | 100 RPM | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | ||||||||||
3 |
Is the voltage within the specified range? | 9-12 V | Go to Step 5 | Go to Step 4 | ||||||||||
4 | Test the OSS high signal circuit and the OSS low signal circuit for the following conditions:
Refer to Circuit Testing or Wiring Repairs . Did you find and correct a condition? | -- | Go to Step 9 | Go to Step 8 | ||||||||||
5 | Test the OSS low signal circuit for a short to ground. Refer to Testing for Short to Ground or Wiring Repairs . Did you find and correct a condition? | -- | Go to Step 9 | Go to Step 6 | ||||||||||
6 |
Did you find and correct a condition? | -- | Go to Step 9 | Go to Step 7 | ||||||||||
7 | Replace the OSS. Refer to Output Speed Sensor Replacement . Did you complete the repair? | -- | Go to Step 9 | -- | ||||||||||
8 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Is the action complete? | -- | Go to Step 9 | -- | ||||||||||
9 | Perform the following procedure in order to verify the repair:
Does the DTC reset? | -- | Go to Step 2 | Go to Step 10 | ||||||||||
10 | 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? | -- | System OK |
