Rotational speed sensor for output shaft, signal missing
Check the cable harness. Try fitting a new sensor and check whether the fault disappears. Contact an Allison dealer.
What you'll see
No driver-visible symptom recorded.
System reaction
The Allison fault code number is: P0722.The fault code is set when any of the following occurs: Improbably large changes (at least 600 rpm) in shaft rotational speed when the current gear is neutral. The shaft rotational speed is less than 61 rpm and the current gear is 3, 4 or 5 for more than 1 second. The shaft rotational speed is less than 61 rpm for more than 1 second when 2nd gear is engaged and the engine's net torque is +/- 1 Nm or turbine speed is higher than 800 rpm.For the fault code to be set, the following conditions must be met: Gear changing has been completed. The engine is running.Current gear is not neutral. No basic hydraulic setting conditions because voltage has been lost. The oil sump temperature is above -1.1°C.Turbine speed higher than 600 rpm.If the fault occurs when driving with the forward gear range selected and a gear-change has been carried out, the gearbox maintains the current gear. If the fault occurs when driving with the forward gear range selected and gear changing is in progress, the gearbox returns to the previous gear after which the gearbox carries out the requested gear-change.The lock-up cannot be locked.The control unit shuts off gear changing adaptation. The fault code is cleared automatically, when the vehicle has completed 40 start-up cycles without the fault being detected again.
Diagnostic depth
There is no signal from the rotational speed sensor which is located on the output shaft.
A possible cause of the fault may be damage to the cable harness or a defective rotational speed sensor.