AUTOMATIC TRANSAXLE
ENGINE (NON-TURBO)> On-vehicle Service
TORQUE CONVERTER STALL TESTING
The torque converter stall test is used primarily to determine
overrunning clutch operation.
Use the scan tool and a tachometer to
test.
Determine engine rpm with the transaxle in
at wide open throttle, and vehicle
To keep the vehicle stationary and to avoid creepin g or lurching
forward, apply both the service brakes and the parking brake.
WARNING
When performing a stall test, always apply both the ser-
vice brakes and parking brake. Also, do not let any one
stand in front of the vehicle during
NOTE
Avoid keeping the throttle open for more than 5 seconds
at a time. Allow the transmission fluid to cool
tests by placing the transaxle in neutral, raising the
rpm slightly for approximately 20 seconds.
TORQUE CONVERTER CLUTCH FAILURE
One type of over-running clutch failure is a slipping
clutch. With this type of failure, the will exhibit normal
transaxle operation at highway speeds will have poor
acceleration.
Another type of over-running clutch failure is a seized
clutch.
With this type of failure, the vehicle acceleration may be ac-
ceptable but a high throttle is required to maintai n vehicle
speed.
The vehicle may seem like it has a loss of power.
With either type of failure, poor fuel economy and transaxle
fluid over-hearting may be the result.
STALL SPEED ABOVE SPECIFICATION
If the stall speed exceeds 2,440 by more than 200
a clutch is slipping.
Diagnose the clutch circuits by performing hydrauli c and air
pressure tests.
The clutches of the transaxles may also be checked
using information given through the input and outpu t speed
sensors to the TCM.
STALL SPEED BELOW SPECIFICATION
If stall speed is below specification, the
over-running clutch is slipping. During the road te st, if poor
acceleration occurs through the gears with normal t ransaxle
operation at highway speeds, the vehicle has a slip ping
clutch.
NORMAL STALL SPEED AND ACCELERATION
If stall speed and acceleration appear normal, but it takes
excessively high throttle opening to maintain vehic le speed,
the starter’s over-running clutch is seized.
This will impede the flow of fluid within the torqu e converter,
causing excessive use of power from the engine for cruising.
CONVERTER NOISE
While performing the stall test, listen for abnormal noise com-
ing from the converter area.
A whining noise due to fluid flow within the conver ter is consid-
ered normal.
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