Symptom:
P0740-TORQUE CONVERTER CLUTCH CONTROL CIRCUIT
When Monitored and Set Condition:
P0740-TORQUE CONVERTER CLUTCH CONTROL CIRCUIT
When Monitored: The Torque Converter Clutch (TCC) is in FEMCC or PEMCC, Trans-
mission temperature is hot, Engine temperature is greater than 38° C or 100° F,
Transmission Input Speed greater than 1750 RPM, TPS less than 30°.
Set Condition: The TCC is modulated by controlling the duty cycle of the L/R Solenoid
until the difference between the Engine and the Transmission Input Speed RPM or duty
cycle is within a desired range. The DTC is set after the period of 10 seconds and 3
occurrences of either: FEMCC - with slip greater than 100 RPM or PEMCC - duty cycle
greater than 85%.
POSSIBLE CAUSES
RELATED DTC’S PRESENT
INTERNAL TRANSMISSION
INTERMITTENT WIRING AND CONNECTORS
TEST ACTION APPLICABILITY
1 NOTE: Low fluid level can be the cause of many transmission problems. If
the fluid level is low locate and repair the leak then check and adjust the
fluid level per the Service Information.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIIIt, read Engine DTC’s. Check and repair all Engine DTC’s prior to
performing any transmission symptom diagnostics.
With the DRBIIIt, read Transmission DTC’s. Record all DTC’s and 1 Trip Failures.
NOTE: Diagnose 1 Trip Failures as a fully matured DTC.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test
for P0706 Check Shifter Signal.
For Gear Ratio DTC’s, check and record all CVI’s.
Most DTC’s set on start up but some must be set by driving the vehicle such that all
diagnostic monitors have run.
NOTE: Verify flash level of Powertrain Control Module. Some problems are
corrected by software upgrades to the Transmission and Engine software.
NOTE: Check for applicable TSB’s related to the problem.
Perform this procedure prior to Symptom diagnosis.
All
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