7A1–24 TRANSMISSION CONTROL SYSTEM (4L30–E)
Intermittent Conditions
If the Tech 2 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. Intermittents rarely occur
inside sophisticated electronic components such as the
PCM.
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. Electromagnetic 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 F2: SNAPSHOT mode of the Tech 2 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 the test
drive, trigger the snapshot manually.
After the snapshot has been triggered, command the
Tech 2 to play back the flow of data recorded from each of
the various sensors. Sign of an intermittent fault in a
sensor circuit is a sudden unexplainable jump in data
values out of the normal range.