Engine Coolant Temperature Sensor; Knock Sensors-3.5L Engine - DaimlerChrysler LH New Yorker 1994 Electronic Service Manual

Fig. 19 Crankshaft Position Sensor Location
The coil pack consists of 3 coils molded together
(Fig. 20). High tension leads route to each cylinder
from the coil. The coil fires two spark plugs every
power stroke. One plug is the cylinder under compres-
sion, the other cylinder fires on the exhaust stroke.
The powertrain control module (PCM) determines
which of the coils to charge and fire at the correct
time.
Coil number one fires cylinders 1 and 4, coil num-
ber two fires cylinders 2 and 5, and coil number three
fires cylinders 3 and 6.
Fig. 20 Coil Pack
The coil's low primary resistance (0.5 - 0.7 ohm)
allows the PCM to fully charge the coil for each firing.

ENGINE COOLANT TEMPERATURE SENSOR

The engine coolant temperature sensor threads into
the water jacket next to thermostat housing (Fig. 21
or Fig. 22). The sensor provides an input to the pow-
ertrain control module (PCM). As coolant temperature
varies, the sensor resistance changes, resulting in a
different input voltage to the PCM.
IGNITION SYSTEMS
The PCM contains different spark advance sched-
ules for cold and warm engine operation. The sched-
ules reduce engine emission and improve driveability.
When the engine is cold, the PCM will demand
slightly richer air-fuel mixtures and higher idle
speeds until normal operating temperatures are
reached.
The engine coolant sensor input also determines
operation of the low and high speed cooling fans.
Fig. 21 Engine Coolant Temperature Sensor—
3.3L Engine
Fig. 22 Engine Coolant Temperature Sensor—
3.5L Engine
KNOCK SENSORS—3.5L ENGINE
The 3.5L engine has two knock sensors. One sensor
for the right bank of cylinders, one for the left bank.
The knock sensors thread into the top of the cylinder
block below the cylinder heads (Fig. 23). When a
knock sensor detects a knock in one of the cylinders,
it sends a input signal to the PCM. In response, the
PCM retards ignition timing by a scheduled amount.
Knock sensors contain a crystal 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 out-
put voltage also increases.
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