Schedule Condition Expected Operation
Extreme Cold Oil temperature at start-up below
-16° F
Park, Reverse, Neutral and 2nd
gear only (prevents shifting which
may fail a clutch with frequent
shifts)
Cold Oil temperature at start-up above
-12° F and below 36° F
– Delayed 2-3 upshift
(approximately 22-31 mph)
– Delayed 3-4 upshift (45-53 mph)
– Early 4-3 costdown shift
(approximately 30 mph)
– Early 3-2 coastdown shift
(approximately 17 mph)
– High speed 4-2, 3-2, 2-1 kickdown
shifts are prevented
– No EMCC
Warm Oil temperature at start-up above
36° F and below 80 degree F
– Normal operation (upshift,
kickdowns, and coastdowns)
– No EMCC
Hot Oil temperature at start-up above
80° F
– Normal operation (upshift,
kickdowns, and coastdowns)
– Full EMCC, no PEMCC except to
engage FEMCC (except at closed
throttle at speeds above 70-83 mph)
Overheat Oil temperature above 240° F or
engine coolant temperature above
244° F
– Delayed 2-3 upshift (25-32 mph)
– Delayed 3-4 upshift (41-48 mph)
– 3rd gear FEMCC from 30-48 mph
– 3rd gear PEMCC from 27-31 mph
Super Overheat Oil temperature above 260° F – All “Overheat” shift schedule
features apply
– 2nd gear PEMCC above 22 mph
– Above 22 mph the torque
converter will not unlock unless the
throttle is closed or if a wide open
throttle 2nd PEMCC to 1 kickdown
is made
TRANSMISSION CONTROL RELAY
DESCRIPTION
The transmission control relay is located in the
Power Distribution Center (PDC) on the left side of
the engine compartment (Fig. 16).
OPERATION
The relay is supplied fused B+ voltage, energized
by the TCM, and is used to supply power to the sole-
noid pack when the transmission is in normal oper-
ating mode. When the relay is “off”, no power is
supplied to the solenoid pack and the transmission is
in “limp-in” mode. After a controller reset (ignition
key turned to the “run” position or after cranking
engine), the TCM energizes the relay. Prior to this,
the TCM verifies that the contacts are open by check-
ing for no voltage at the switched battery terminals.
After this is verified, the voltage at the solenoid pack
pressure switches is checked. After the relay is ener-
gized, the TCM monitors the terminals to verify that
the voltage is greater than 3 volts.
LH 42LE TRANSAXLE 21 - 13
DESCRIPTION AND OPERATION (Continued)
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