Section 120-0010
Transmission - Transmission and Mounting
8
SM 1574 12-98
for mechanical troubleshooting, as outlined in the
'Mechanical Trouble Shooting' charts, before carrying
out electrical troubleshooting procedures.
WARNING
Be sure to apply the parking brake, switch off
the engine and block all road wheels before
troubleshooting the vehicle. Should it be
necessary to run the engine, it is imperative
that an operator be present in the cab at all
times, even at idle.
SPECIAL TOOLS
There are no special tools required for the
procedures outlined in this section. Refer to Section
300-0070, SERVICE TOOLS for part numbers of
service tools which should be used in conjunction with
procedures outlined in the transmission manufacturers
service manual, and general service tools required.
These tools are available from your dealer.
6. During the stall check the transmission oil
temperature should rise while the engine is under
load and drop when the transmission is returned to
neutral. Should the temperature fail to drop it
indicates that there is a problem with the converter.
7. After making allowances for elevation, a low engine
speed may indicate the engine is not delivering full
power. Refer to engine service manual for engine
repair information.
Electronic Troubleshooting
Refer to Section 120-0070, CEC SHIFT SYSTEM for
general electrical troubleshooting. For more detailed
electrical troubleshooting refer to the Allison
Transmission Commercial Electronic Control (CEC)
Troubleshooting Manual SA2712A.
Mechanical Troubleshooting
It is recommended to follow the procedures laid down
MECHANICAL TROUBLESHOOTING CHART
CONDITION REASON REMEDY
A - Transmission overheats High or low oil level Restore proper oil level
Aerated (foaming) oil Refer to condition 'B'
Vehicle overloaded Reduce load
Engine coolant overheated Correct engine overheating
Transmission oil cooler or Clean or replace oil cooler or lines
lines kinked or clogged
Low coolant level Add coolant, check for leaks
Oil leaking Check transmission and lines for leaks
Low main pressure Refer to condition 'V'
Low converter-out pressure Refer to condition 'U'
Vehicle brakes dragging Check parking and service brakes
Torque converter stator locked Check for low top speed of vehicle. Check
torque converter components.
Clutch slipping Overhaul transmission. Replace worn piston
seal rings or clutch plates.
B - Oil is aerated (foaming) Incorrect type of oil used Change oil. Use only oil specified in Section
300-0020, LUBRICATION SYSTEM.
High or low oil level Restore proper oil level
Air entering suction side of Check oil pump bolts and gasket
oil pump
Water in oil Check for source, clean system
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