P0722
OUTPUT SPEED SENSOR - P0721/P0722The output speed sensor is located on the rear of the valve block assembly inside the transmission. Connection is made via pins A and F of the 9-way transmission connector located on the left hand side of the transmission assembly. The wiring runs through the rotary switch harness and the vehicle gearbox harness to the TCM on pins 2 and 38 of the 55 way multiplug. These wires are shielded by a screen which is terminated on pin 20 of the TCM multi-plug. The sensor detects the motion of the output shaft via a 36 toothed wheel.
Output Speed Sensor Circuit Range/Performance - P0721
This test is only performed when a downshift takes place and therefore the vehicle must be in a forward gear ie D, 3, 2, 1. A fault will be flagged if the engine speed is above a threshold which is dependant on the shift and the state of the lock up clutch.
This fault code would suggest that there is an intermittent fault in the circuit.
Output Speed Sensor Circuit No Signal - P0722
The background diagnostic software continuously monitors the output speed and flags this fault if the output speed is zero when the engine speed is greater than 2000 rpm and a forward gear D, 3, 2, 1, is selected.
This fault code would suggest a permanent fault, either open circuit, short to ground or short circuit to battery positive voltage (+12V nominal).
Possible Causes:
Faulty sensor.
Faulty harness wiring 1 connectors.
Effects:
MIL illuminated.
Transmission warning lamp illuminated.
Maximum pressure applied.
Limp home mode applied.
Remedy:
Renew sensor.
Repair or renew harness/connectors.
Troubleshooting Schematic
Key To Schematic Diagrams
1. Transmission Control Module (TCM)
2. Transmission Unit
3. TCM Multi-pin Connector
4. Transmission Rotary Switch
5. Transmission Connector Plug
6. Engine Control Module
7. Instrument Pack
8. ABS/Traction Control Control Module
9. Kickdown Switch
Pin Outs