1. The manufacturer concurs with performing a full-throttle transmission stall
test.
2. The engine programmable parameter for 0 rpm transmission output speed
is set higher than the value expected at transmission stall speed.
3. The vehicle is in an area in which a transmission stall test can be safely
performed.
4. Make sure the fuel control linkage goes to full throttle and does not stick
when released.
5. Make sure the engine air induction system and exhaust system have no
restrictions.
6. Determine the cold transmission fluid level and adjust as necessary.
7. Connect Allison DOC™ For PC–Service Tool to the vehicle diagnostic
data connector or install an accurate tachometer (do not rely on the vehicle
tachometer).
8. Install a temperature gauge with the probe in the transmission
converter-out (to cooler) line. Allison DOC™ displays sump temperature
only.
9. Install wheel chocks.
10. A driver is in the driver’s position.
11. The vehicles brakes are fully locked.
WARNING: To help avoid personal injury, such as burns, from hot
transmission fluid and/or to help avoid equipment damage, do not stall
the torque converter for more than ten seconds maximum and monitor
transmission fluid temperature. Immediately return the engine to idle if
converter out (to cooler) temperature exceeds 150°C (300°F). Operating
the transmission at high engine power at transmission stall or near stall
conditions causes a rapid rise in the transmission fluid temperature. The
fluid in the transmission torque converter is absorbing all of the engine
power and the vehicle cooling system cannot dissipate the excessive
heat load. Extended operation under high heat load conditions causes
transmission and cooling system damage, and can possibly fail hydraulic
lines causing high temperature fluid.
WARNING: To help avoid personal injury and equipment damage
while conducting a transmission stall test, the vehicle must be positively
prevented from moving. Apply the parking brake, the service brake, and
chock the wheels securely. Warn personnel to keep clear of the vehicle
and its travel path.
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