Jeep Cherokee 2000 Service Manual - page 1537
The D range provides first through fourth gear.
Overdrive fourth gear range is available only when
the shift lever is in D position (Fig. 35).
TRANSMISSION CONTROL MODULE (TCM)
DESCRIPTION
The module determines shift and converter clutch
engagement timing based on signals from sensors.
The valve body solenoids are activated, or deacti-
vated accordingly.
The TCM has a self diagnostic program. Compo-
nent and circuitry malfunctions can be diagnosed
with the DRB scan tool. Once a malfunction is noted
and stored in control module memory, it is retained
even after the problem has been corrected. To cancel
a stored malfunction, disconnect and reconnect the
“Trans.” fuse in the module harness.
SENSORS
Sensors include:
•
throttle position sensor (TPS)
•
transmission speed sensor
•
vehicle speed sensor
•
park/neutral position switch
•
brake switch
OPERATION
The throttle position sensor is mounted on the
throttle body. It electronically determines throttle
position and relays this information to the transmis-
sion control module to determine shift points and
converter clutch engagement.
The transmission speed sensor consists of a rotor
and magnet on the transmission output shaft and a
switch in the extension housing or adapter. The sen-
sor switch is activated each time the rotor and mag-
net complete one revolution. Sensor signals are sent
to the transmission control module.
The park/neutral position switch is mounted on the
valve body manual shaft. The switch signals shift
linkage and manual valve position to the transmis-
sion control module through an interconnecting har-
ness. The switch prevents engine starting in all gears
other than Park or Neutral.
The brake switch is in circuit with the torque con-
verter clutch solenoid. The switch disengages the
converter clutch whenever the brakes are applied.
The switch is mounted on the brake pedal bracket
and signals the transmission control module when
the pedal is pressed or released.
HYDRAULIC SYSTEM
DESCRIPTION
The hydraulic system consists of the pump, valve
body and solenoids, and four hydraulic accumulators.
The oil pump provides lubrication and operating
pressure.
The valve body controls application of the clutches,
brakes, second coast band, and the converter clutch.
The valve body solenoids control sequencing of the
1–2, 2–3 and 3–4 shift valves. The solenoids are acti-
vated by signals from the transmission control mod-
ule.
The accumulators are used in the clutch and brake
feed circuits to control initial apply pressure. Spring
loaded accumulator pistons modulate the initial
surge of apply pressure for smooth engagement.
TRANSMISSION COOLER
DESCRIPTION
MAIN COOLER
The transmission main cooler is located in the
radiator. The main cooler can be flushed when neces-
sary, however, the cooler is not a repairable compo-
nent. If the cooler is damaged, plugged, or leaking,
the radiator will have to be replaced.
AUXILIARY COOLER
The auxiliary cooler is mounted in front of the
radiator at the driver side of the vehicle (Fig. 36).
The cooler can be flushed when necessary, while
mounted in the vehicle. The cooler can also be
removed for access, repair, or replacement as needed.
The main and auxiliary coolers should both be
flushed whenever a transmission or converter clutch
Fig. 35 AW–4 Shift Lever Positions And
Transmission Ranges
XJ
AW–4 AUTOMATIC TRANSMISSION
21 - 237
DESCRIPTION AND OPERATION (Continued)