P0722

P0722
Speed sensor, transmission -signal implausible-

Function
The speed sensor is an inductive transmitter. It transmits the transmission output speed to the transmission control unit. This speed is used for speed-dependent calculation of the shifting times and for slip monitoring. The "restricted driving program" is activated in the event of a faulty signal.

Diagnosis conditions
Engine speed >2500 rpm and drive position D.





Wiring diagram





Diagnosis procedure

NOTE: The speed signal can be tested with system tester 9288 (actual values/transmission speed).

Check speed sensor with wiring.
1. Pull off transmission control unit connector.
2. Connect ohmmeter to transmission control unit connector pin 14 and pin 42.
- Indication: approx. 350 ohms





Check wires from transmission control unit to transmission connector for continuity.
1. Additionally disconnect connector on transmission.
2. Connect ohmmeter to transmission control unit connector, pin 14, and transmission connector, pin F, or pin 42 and pin A.
- Indication: ...5 ohms
- If infinite resistance is indicated, check wiring harness for crushing and chafing damage.

Check wires from transmission control unit to transmission connector for short circuit to ground.
1. Connect ohmmeter to transmission control unit connector, pin 14, and ground or pin 42 and ground.
- Indication: infinite resistance
- If 0...5 ohms is indicated, check wiring harness for crushing and chafing damage.

Check wires from transmission control unit to transmission connector for short circuit to plus.
1. Switch on ignition.
2. Connect voltmeter to transmission control unit connector, pin 14, and ground.
- Indication: 0 Volt
- If battery voltage is indicated, check wiring harness for crushing and chafing damage.