P1710

P1710
Speed signal (FR) -signal implausible-

P1715
Speed signal (FL) -signal implausible-

Function
The transmission control unit receives the speed signals of the two front wheels from the ABS control unit. For locking in gears during curves, the transmission control unit calculates the lateral acceleration from the vehicle speed and the speed difference between the front wheels. Shifting is not performed if the stipulated thresholds are exceeded; the slip monitoring function and the manual program are inactive.

Diagnosis conditions
The wheel speeds of the front wheels must be detected when the transmission output speed corresponds to approx. 60 km/h.





Wiring diagram





Diagnosis procedure

NOTE: The speed signal can be checked with the system tester 9288 (actual values - V (FR) and V (FL)). For this purpose, jack up the vehicle and turn the wheels manually.





Test speed signal with oscilloscope at transmission control unit connector.
1. Pull off transmission control unit connector.
2. Connect oscilloscope to transmission control unit connector pin 39 (or pin 40) in accordance with the manufacturer's instructions.
3. Jack up vehicle at the front.
4. Switch on ignition.
5. Manually turn the front-right wheel or front-left wheel in driving direction. The following display must be visible.

Check wire from transmission control unit to ABS control unit for continuity.
1. Pull off transmission control unit connector.
2. Pull off ABS control unit connector.
2. Connect ohmmeter to transmission control unit connector pin 39 (or pin 40) and ABS control unit connector pin 42 (or pin 9).
- Indication: 0...5 ohms
- If infinite resistance ohm is indicated, check wiring harness for crushing and points of contact.

Check wire from transmission control unit to ABS control unit for short circuit to ground.
1. Connect ohmmeter to transmission control unit connector pin 39 (or pin 40) and ground.
- Indication: infinite resistance
- If 0...5 ohms is indicated, check wiring harness for crushing and chafing damage.

Check wire from transmission control unit to ABS control unit for short circuit to plus.
1. Switch on ignition.
2. Connect voltmeter to transmission control unit connector pin 39 (or pin 40) and ground.
- Indication: 0 Volt
- If battery voltage is indicated, check wiring harness for crushing and chafing damage.