7A-146 AUTOMATIC TRANSMISSION (4L30-E)
INTERMITTENT CONDITIONS
If the TECH1 displays a diagnostic trouble code as
intermittent, or if after a test drive a DTC does not
reappear though the detection conditions for this
DTC are present: the problem is most likely a faulty
electrical connection or loose wiring. Terminals
and
grounds should always be the prime suspect.
lntermittents rarely occur inside sophisticated
electronic components such
as the TCM.
Use the
DTC information to understand which wires
and sensors are involved.
When an
intermittent problem is encountered,
check suspect circuits for:
(1) Poor terminal to wire connection.
(2) Terminals not fully seated in the connector
body (backed out).
(3) Improperly formed or damaged terminals.
(4) Loose, dirty, or corroded ground connections:
HINT: Any time you have an intermittent in
more than one circuit, check whether the circuits
share a
common ground connection.
(5) Pinched or damaged wires.
(6) Electro-Magnetic Interference (EMI):
HINT:
Check that all wires are properly routed
away from spark plug wires, distributor wires,
coil, and generator. Also check
for improperly
installed electrical options, such as lights, 2-way
radios, etc. Use
the
F3: SNAPSHOT mode of the TECH 1 to help
isolate the cause
of an intermittent fault. The
snapshot
mode will record information before and
after the problem occurs. Set the snapshot
to
"trigger" on the suspect DTC or, if you notice the
reported
symptom during test drive, trigger the
snapshot
manually.
(1) NOTE: When TECH1 is plugged the shifts are
always
done at the maximum pressure. This
means
that if you do SNAPSHOT while driving
you will! notice firm shifts.
After the snapshot has been triggered, command
the TECH1 to play back the flow of data recorded
from each of the various sensors. Signs of an
intermittent fault in a sensor circuit are sudden
unexplainable jump in data values out of the
normal range.
CASE:
problem still not solved GOTO TCM MEM
CAL REPLACEMENT.
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