7A–19 AUTOMATIC TRANSMISSION (4L30–E)
Chart 13: Shudder Only During Torque Converter Clutch (TCC) Applying
StepActionYe sNo
11. TCC shudder is one of the most commonly misdiagnosed
conditions in an automatic transmission. The key to
diagnosing TCC shudder is to note when it happens and under
what conditions. Once the TCC has been fully applied, it is
nearly impossible to make it shudder. TCC shudder (short
burst of noise normally less than 1 second) will only occur
during clutch applying. It is not a steady state condition.
2. Drive until whole drivetrain is at normal operating temperature.
– On 4WD vehicles, the test must be performed with transfer
case selector lever in “2H” position.
– Shudder is a short burst of noise normally less than 1 second
in duration, and can be induced by the following maneuver:
3. From coast condition at 50 mph in “D” range (Normal mode),
depress the throttle to 1/4-1/3 throttle. If present, shudder will
occur within 5 seconds together with TCC application.(The
scan tool may be used to determine the exact time of TCC
applying)
Was the problem found?
Replace
transmission fluid
and filter (remove
both pans) and
flush cooler lines.
Replace
converter
assembly and
O-ring on turbine
shaft
Perform
mechanical
inspection of
other drivetrain
components.
Chart 14: Possible Causes Of Transmission Noise
CAUTION: Before checking transmission for what
is believed to be transmission noise, ensure
presence and positioning of insulating plugs, pads
etc. Also make sure that noise does not come from
other drivetrain components.
Condition
Possible causeCorrection
Whine or BuzzOil level lowFill with ATF, check for external
leaks.
Plugged or restricted oil filterInspect oil filter.
Replace oil filter or ATF as necessary.
Damaged oil filter gasketReplace oil filter gasket.
Knocking noise from front of
transmission
Loose bolts (Converter to flex plate)Tighten to specifications.
transmission.Cracked or broken flex plateReplace flex plate.
Converter damagedReplace converter.
Knocking noise while driving, mostly
on acceleration.Transmission mount loose or brokenTighten mount bolts or replace
transmission mount.
Cooler line mounts loose or brokenTighten or replace cooler line
mounts.
Cooler lines touching body or frameRepair or replace as necessary.
Knocking noise when vehicle is
stationary
Loose flex plate mounting boltsTighten to specifications.
stationary.Cracked or broken flex plateReplace flex plate.
Damaged converterReplace converter.
