Throttle Position Sensor (Tps); General Information - Chrysler 1998 Voyager Service Manual

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GENERAL INFORMATION (Continued)
Fig. 12 Engine Coolant Temperature Sensor—3.3/

THROTTLE POSITION SENSOR (TPS)

The TPS mounts to the side of the throttle body
(Fig. 13).
The TPS connects to the throttle blade shaft. The
TPS is a variable resistor that provides the Power-
train Control Module (PCM) with an input signal
(voltage). The signal represents throttle blade posi-
tion. As the position of the throttle blade changes,
the resistance of the TPS changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
powertrain control module) represents throttle blade
position. The TPS output voltage to the PCM varies
from approximately 0.40 volt at minimum throttle
opening (idle) to a maximum of 3.80 volts at wide
open throttle.
Along with inputs from other sensors, the PCM
uses the TPS input to determine current engine oper-
ating conditions. The PCM also adjusts fuel injector
pulse width and ignition timing based on these
inputs.
LOCK KEY CYLINDER
The lock cylinder is inserted in the end of the
housing opposite the ignition switch. The ignition key
rotates the cylinder to 5 different detents (Fig. 14):
• Accessory
• Off (lock)
• Unlock
• On/Run
• Start
3.8L
Fig. 13 Throttle Position Sensor and Idle Air Control
Fig. 14 Ignition Lock Cylinder Detents
KNOCK SENSOR
The knock sensor threads into the side of the cyl-
inder block in front of the starter motor. When the
knock sensor detects a knock in one of the cylinders,
it sends an input signal to the PCM. In response, the
PCM retards ignition timing for all cylinders by a
scheduled amount.
Knock sensors contain a piezoelectric material
which constantly vibrates and sends an input voltage
(signal) to the PCM while the engine operates. As the
intensity of the crystal's vibration increase, the knock
sensor output voltage also increases.
IGNITION SYSTEM
Motor
8D - 7