Solenoid PCS4 jammed in connected position
â–¶ How to fix
Contact an Allison dealer.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
Detection
PCS4 still supplies clutch C4 even though it should be shut off. The fault is detected when control unit detects that the previous gear ratio remains engaged for too long even though the clutch has been commanded to shut off.
Possible cause
The cause can be: Erratic sensor signal from turbine or output shaft speed.Obstruction in a discharge circuit for clutch C4.Faulty PCS4 solenoid.A governor valve for PCS4 is stuck.