Chrysler neon 1997 Service Manual page 1324

PL
DESCRIPTION AND OPERATION (Continued)
conditioning pressure drops approximately 40 psi, the
pressure switch opens and the fan turns off.
The PWM relay is located on the left front inner
frame just behind the radiator.
SPEED CONTROL—PCM INPUT
The speed control system provides five separate
voltages (inputs) to the Powertrain Control Module
(PCM). The voltages correspond to the ON/OFF, SET,
RESUME and CANCEL.
The speed control ON voltage informs the PCM
that the speed control system has been activated.
The speed control SET voltage informs the PCM that
a fixed vehicle speed has been selected. The speed
control RESUME voltage indicates the previous fixed
speed is requested. The speed control CANCEL volt-
age tells the PCM to deactivate but retain set speed
in memory (same as depressing the brake pedal). The
speed control OFF voltage tells the PCM that the
speed control system has deactivated. Refer to Group
8H for more speed control information.
SCI RECEIVE—PCM INPUT
SCI Receive is the serial data communication
receive circuit for the DRB scan tool. The Powertrain
Control Module (PCM) receives data from the DRB
through the SCI Receive circuit.
TACHOMETER—PCM OUTPUT
The PCM operates the tachometer on the instru-
ment panel. The PCM calculates engine RPM from
the crankshaft position sensor input.
TORQUE CONVERTOR CLUTCH SOLENOID—PCM
OUTPUT
Three-speed automatic transaxles use a torque con-
verter clutch solenoid. The PCM controls the engage-
ment of the torque converter clutch through the
solenoid (Fig. 29). The torque converter clutch is
engaged up only in direct drive mode. Refer to Group
21 for transmission information.
DIAGNOSIS AND TESTING
VISUAL INSPECTION—SOHC
Before diagnosing or servicing the fuel injection
system, perform a visual inspection for loose, discon-
nected, or misrouted wires and hoses (Fig. 30). A
thorough visual inspection that includes the following
checks saves unnecessary test and diagnostic time.
(1) Inspect the battery connections. Clean corroded
terminals (Fig. 31).
(2) Check the 2 PCM 40-way connector for
stretched wires on pushed out terminals (Fig. 31).
TRANSAXLE AUTOMATIC CLUTCH SOLE- VERTOR TORQUE HOUSING BATTERY NOID CON- TRIBUTION POWER
Fig. 29 Torque Convertor Clutch Solenoid
Fig. 30 2.0L SOHC Engine Compartment
Fig. 31 Battery, PCM, and PDC
CENTER DIS- PARK/NEUTRAL SWITCH WASHER WINDSHIELD SPEED PCM CONTROL BOTTLE SERVO FLUID
FUEL SYSTEM 14 - 37