automatic transmission JEEP WRANGLER 1994 User Guide

Fig. 4 Torque Converter With Modulated Clutch
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Fig. 7 Component Function Chart
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Fig. 9 Two-Section Transmission Valve Body
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Fig. 10 Upper Body Components
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Fig. 13 Primary Regulator Valve
Fig. 14 Throttle Valve And Downshift Plug
Fig. 15 Cut-Back Valve
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Fig. 18 1-2 Shift Valve
Fig. 17 Converter Clutch Relay Valve
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Fig. 20 3-4 Shift Valve
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Fig. 22 Low Coast Modulator Valve
Fig. 23 Accumulator Control Valve
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Fig. 25 Transmission Valve Body Solenoids
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MULTI-PORT FUEL INJECTION (MFI)ÐCOMPONENT DESCRIPTION/SYSTEM
OPERATION
INDEX
page page
Air Conditioning (A/C) Clutch RelayÐPCM Output.24
Air Conditioning (A/C) ControlsÐPCM Input.... 19
Auto Shut Down (ASD) RelayÐPCM Output.... 24
Automatic Shut Down (ASD) SenseÐPCM Input . 19
Battery VoltageÐPCM Input................ 19
Brake SwitchÐPCM Input.................. 20
Camshaft Position SensorÐPCM Input........ 20
Crankshaft Position SensorÐPCM Input....... 20
Data Link ConnectorÐPCM Input............ 20
Data Link ConnectorÐPCM Output........... 24
EMR LampÐPCM Output.................. 24
Engine Coolant Temperature SensorÐPCM Input . 21
Extended Idle SwitchÐPCM Input............ 21
Fuel InjectorsÐPCM Output................ 25
Fuel Pressure Regulator................... 30
Fuel Pump RelayÐPCM Output............. 25
Fuel Rail............................... 30
General Information....................... 17
Generator FieldÐPCM Output............... 25
Generator LampÐPCM Output.............. 25
Idle Air Control (IAC) MotorÐPCM Output...... 25
Ignition Circuit SenseÐPCM Input............ 21
Ignition CoilÐPCM Output.................. 26Intake Air Temperature SensorÐPCM Input.... 20
Malfunction Indicator LampÐPCM Output...... 26
Manifold Absolute Pressure (MAP) SensorÐ
PCM Input............................ 21
Open Loop/Closed Loop Modes of Operation . . . 27
Overdrive/Override Switch.................. 22
Oxygen (O2S) SensorÐPCM Input........... 22
Park/Neutral SwitchÐPCM Input............. 22
Power Ground........................... 22
Power Steering Pressure SwitchÐPCM Input . . . 22
Powertrain Control Module (PCM)............ 18
Radiator Fan RelayÐPCM Output............ 26
SCI ReceiveÐPCM Input.................. 22
SCI TransmitÐPCM Output................. 26
Sensor ReturnÐPCM Input................. 23
Shift IndicatorÐPCM Output................ 26
Speed ControlÐPCM Input................. 23
Speed ControlÐPCM Output................ 27
TachometerÐPCM Output.................. 27
Throttle Body............................ 29
Throttle Position Sensor (TPS)ÐPCM Input..... 23
Torque Converter Clutch RelayÐPCM Output . . . 27
Vehicle Speed SensorÐPCM Input........... 23
GENERAL INFORMATION
All 2.5L 4 cylinder and 4.0L 6 cylinder engines are
equipped with sequential Multi-Port Fuel Injection
(MFI). The MFI system provides precise air/fuel ra-
tios for all driving conditions.
The Powertrain Control Module (PCM) operates
the fuel system. The PCM was formerly referred to
as the SBEC or engine controller. The PCM is a pre-
programmed, dual microprocessor digital computer.
It regulates ignition timing, air-fuel ratio, emission
control devices, charging system, speed control, air
conditioning compressor clutch engagement and idle
speed. The PCM can adapt its programming to meet
changing operating conditions.
Powertrain Control Module (PCM) Inputsrep-
resent the instantaneous engine operating conditions.
Air-fuel mixture and ignition timing calibrations for
various driving and atmospheric conditions are pre-
programmed into the PCM. The PCM monitors and
analyzes various inputs. It then computes engine fuel
and ignition timing requirements based on these in-
puts. Fuel delivery control and ignition timing will
then be adjusted accordingly.
Other inputs to the PCM are provided by the brake
light switch, air conditioning select switch and the
speed control switches. All inputs to the PCM are
converted into signals.
Electrically operated fuel injectors spray fuel in
precise metered amounts into the intake port directlyabove the intake valve. The injectors are fired in a
specific sequence by the PCM. The PCM maintains
an air/fuel ratio of 14.7 to 1 by constantly adjusting
injector pulse width. Injector pulse width is the
length of time that the injector opens and sprays fuel
into the chamber. The PCM adjusts injector pulse
width by opening and closing the ground path to the
injector.
Manifold absolute pressure (air density) and engine
rpm (speed) are the primary inputs that determine
fuel injector pulse width. The PCM also monitors
other inputs when adjusting air-fuel ratio.
Inputs That Effect Fuel Injector Pulse Width
²Exhaust gas oxygen content
²Engine coolant temperature
²Manifold absolute pressure (MAP)
²Engine speed
²Throttle position
²Battery voltage
²Air conditioning selection
²Transmission gear selection (automatic transmis-
sions only)
²Speed control
The powertrain control module (PCM) adjusts igni-
tion timing by controlling ignition coil operation. The
ignition coil receives battery voltage when the igni-
tion key is in the run or starter position. The PCM
provides a ground for the ignition coil. The coil dis-
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