Code Listings And Procedures
(Allison 4
th
Generation Controls)
(cont’d)
P0973, P0976
Shift Solenoid
Circuit Low
1. Check:
a. Main transmission connector is tight, clean, and
undamaged.
b. TCM connector is tight, clean, and undamaged.
c. Wiring harness has no opens, shorts-between-wires,
or shorts-to-ground.
P0974, P0977
Shift Solenoid
Circuit High
1. Check:
a. Main transmission connector is tight, clean, and
undamaged.
b. TCM connector is tight, clean, and undamaged.
c. Wiring harness has no shorts-between-wires.
P0975
Shift Solenoid
Circuit Open
1. Check:
a. Main transmission connector is tight, clean, and
undamaged.
b. TCM connector is tight, clean, and undamaged.
c. Wiring harness has no opens.
P0989, P0990
Retarder
Pressure
Sensor Circuit
Fault
1. Check:
a. Retarder pressure sensor connector is tight, clean,
and undamaged.
b. TCM connector is tight, clean, and undamaged.
c. Retarder pressure circuit has no opens,
shorts-between-wires, or shorts-to-ground.
P1891, P1892
Throttle
Position PWM
Signal Circuit
Fault
1. Check:
a. PWM throttle position sensor connector is tight,
clean, and undamaged.
b. TCM connector is tight, clean, and undamaged.
c. PWM throttle position sensor circuit has no opens,
shorts-between-wires, or shorts-to-ground.
P2184, P2185
Engine
Coolant Temp
Sensor Circuit
Fault
1. Check:
a. Engine coolant temperature sensor connector is
tight, clean, and undamaged.
b. TCM connector is tight, clean, and undamaged.
c. Engine coolant temperature sensor circuit has no
opens, shorts-between-wires, or shorts-to-ground.
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