Trouble Code Conditions

SPECIAL TOOLS
Test box tool No. 981 3190, or equivalent
Volvo scan tool No. 998 8686, or equivalent

CONDITION
The transmission speed signal is sent by a sensor on the transmission. The Transmission Control Module (TCM) uses the signal to determine the input shaft speed after the torque converter. This signal is used to compare the transmission speed with vehicle speed. The TCM uses this comparison to calculate gear-shift timing. The transmission speed and vehicle speed data are also utilized in modulating system pressure, lock-up function control and in torque limiting. The result is smooth gear-shifting. Diagnostic Trouble Code (DTC) AT-311 is posted if the TCM does not register this signal when vehicle speed exceeds 25 km/h.

SUBSTITUTE VALUE
The TCM "Emergency mode II" program is initiated.

POSSIBLE SOURCE
- Open-circuit in the signal cable (+) or signal cable (-).
- Short-circuit to supply voltage or ground in the signal cable
- Short-circuit to supply voltage in the signal cable (-).
- Short circuit between the signal (+) wiring and signal (-) wiring.
- Defective speed sensor
- Contact resistance in terminals

FAULT SYMPTOM(S)
- The combined instrument panel warning lamp flashes.
- No lock-up function.
- No adaption of the gear slippage times at high altitude (High Altitude Compensation)
- No reduction of system pressure when shifting, making shifting harsher.
- No reduction of system pressure when moving the gear selector between positions P-R, N-R and N-D which causes harsh gear meshing.
- No torque limiting request to Engine Control Module (ECM) when shifting

NOTE:
- The Motronic 4.4 ECM posts a DTC when the transmission sends a Malfunction Indicator Lamp (MIL) request
- Erase this DTC in the Motronic ECM when the transmission fault has been repaired.

TESTING PROCEDURE
- Start fault-tracing at signal missing. Signal Missing