Chrysler 1998 Viper RT/10 Owner's Manual page 742

14 - 2 8 FUEL SYSTEM
S R
DESCRIPTION AND OPERATION (Continued)
the fan off when coolant temperature drops to 94°C
(201°F). Also, the P C M energizes the O N relay when-
ever the A/C system operates. Refer to Radiator F a n
L O W / H I G H Relay for fan operation.
RADIATOR FAN LOW/HIGH RELAY—PCM OUTPUT
The radiator fan L O W / H I G H relay works i n con-
junction w i t h the radiator fan O N relay. I f the cool-
ant temperature is below 102°C (216°F) the current
flow for the fan is through the normally closed con-
tacts of the L O W / H I G H relay. I f the coolant temper-
ature is above 102°C (216°F) the P C M grounds the
L O W / H I G H relay and the radiator fan changes to
h i g h speed. The P C M turns off h i g h speed fan oper-
ation w h e n coolant temperature drops to 102°C
(216°F). The low speed w i l l continue u n t i l tempera-
ture drops below 94°C (201°F). Cooling fan t u r n s off
at 77 mph, w h e n accelerating, and turns back on at
67 mph.
REVERSE LOCKOUT SOLENOID
The reverse lockout solenoid prevents the operator
from shifting into reverse when the vehicle is speed
is greater t h a n 5 m p h . When vehicle speed is less
t h a n 5 m p h the P C M provides a ground for the sole-
noid (energized) and allows shifting. When vehicle
speed is greater t h a n 5 m p h the solenoid is deacti-
vated and prevents the transmission from being
shifted into reverse (Fig. 10).
FIRST TO FOURTH GEAR SHIFT INDICATOR
LAMP—PCM OUTPUT
The P C M operates the first gear to fourth gear
shift lamp. The lamp informs the driver to shift into
fourth gear on the next transmission upshift. The
P C M illuminates the shift lamp when the following
conditions have been met:
• Vehicle speed between 12 and 18 m p h
• Transmission i n first gear
• Engine speed greater t h a n 608 R P M
• Throttle position less t h a n 23 percent (less t h a n
0.68 volts over closed t h r o t t l e TPS voltage)
• Coolant temperature above 41°C (106°F)
SKIP SHIFT SOLENOID—PCM OUTPUT
The skip shift solenoid prevents the operator from
shifting into second or t h i r d gear d u r i n g certain con-
ditions. The P C M controls the skip shift solenoid
(Fig. 13). The P C M locks out second and t h i r d gear
when a l l of the following conditions are met:
• Engine coolant exceeds 41°C (106°F)
• Vehicle speed is between 12 and 18 M P H
• Engine operating above 608 R P M
• The P C M verified first gear speed/RPM
• Throttle position sensor (TPS) signal is less t h a n
0.068 volt above closed throttle (23 percent t h r o t t l e
opening)
The solenoid resets when vehicle speed drops below
2 M P H .
SCI RECEIVE—PCM OUTPUT
SCI Receive is t h e . serial data communication
receive circuit for the DRB scan tool. The Powertrain
Control Module (PCM) receives data from the DRB
t h r o u g h the SCI Receive circuit.
TACHOMETER—PCM OUTPUT
The P C M operates the tachometer on the i n s t r u -
ment panel. The P C M calculates engine R P M from
the crankshaft position sensor i n p u t .
D I A G N O S I S A N D T E S T I N G
VISUAL INSPECTION
Before diagnosing or servicing the fuel injection
system, perform a visual inspection for loose, discon-
nected, or misrouted wires and hoses. A thorough
visual inspection t h a t includes the following checks
saves unnecessary test and diagnostic time.
(1) Inspect the throttle position sensor connector.
Verify the connector is attached to the sensor (Fig.
16).
Fig. 16 Throttle Position Sensor
(2) Inspect vacuum connections at the intake man-
ifold for leaks (Fig. 16).
(3) Verify the correct electrical connector is
attached to each injector (Fig. 17). Make sure the
number on the tag attached to the connector corre-
sponds w i t h the injector.