6E–520
6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS
General Description (PCM and
Sensors)
58X Reference PCM Input
The powertrain control module (PCM) uses this signal
from the crankshaft position (CKP) sensor to calculate
engine RPM and crankshaft position at all engine speeds.
The PCM also uses the pulses on this circuit to initiate
injector pulses. If the PCM receives no pulses on this
circuit, DTC P0337 will set. The engine will not start and
run without using the 58X reference signal.
A/C Request Signal
This signal tells the PCM when the A/C mode is selected
at the A/C control head. The PCM uses this to adjust the
idle speed before turning “ON” the A/C clutch. The A/C
compressor will be inoperative if this signal is not
available to the PCM.
Refer to
A/C Clutch Circuit Diagnosis section for A/C
wiring diagrams and diagnosis for the A/C electrical
system.
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor provides a signal
used by the powertrain control module (PCM) to calculate
the ignition sequence. The CKP sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position.
Refer to
Electronic Ignition System section for additional
information.
0013
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor is a
thermistor (a resistor which changes value based on
temperature) mounted in the engine coolant stream. Low
coolant temperature produces a high resistance of
100,000 ohms at –40
°
C (–40
°
F). High temperature
causes a low resistance of 70 ohms at 130
°
C (266
°
F).
The PCM supplies a 5-volt signal to the ECT sensor
through resistors in the PCM and measures the voltage.
The signal voltage will be high when the engine is cold and
low when the engine is hot. By measuring the voltage, the
PCM calculates the engine coolant temperature. Engine
coolant temperature affects most of the systems that the
PCM controls.
The Tech 2 displays engine coolant temperature in
degrees. After engine start-up, the temperature should
rise steadily to about 85
°
C (185
°
F). It then stabilizes
when the thermostat opens. If the engine has not been
run for several hours (overnight), the engine coolant
temperature and intake air temperature displays should
be close to each other. A hard fault in the engine coolant
sensor circuit will set DTC P0177 or DTC P0118. An
intermittent fault will set a DTC P1114 or P1115.
0016
Electrically Erasable Programmable Read
Only Memory (EEPROM)
The electrically erasable programmable read only
memory (EEPROM) is a permanent memory chip that is
physically soldered within the PCM. The EEPROM
contains the program and the calibration information that
the PCM needs to control powertrain operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable. If the PCM is replaced, the new PCM
will need to be programmed. Equipment containing the
correct program and calibration for the vehicle is required
to program the PCM.
Fuel Control Heated Oxygen Sensors
The fuel control heated oxygen sensors (Bank 1 HO2S 1
and Bank 2 HO2S 1) are mounted in the exhaust stream
where they can monitor the oxygen content of the exhaust
gas. The oxygen present in the exhaust gas reacts with
the sensor to produce a voltage output. This voltage
should constantly fluctuate from approximately 100 mV to
900 mV. The heated oxygen sensor voltage can be
monitored with a Tech 2. By monitoring the voltage output
of the oxygen sensor, the PCM calculates the pulse width
command for the injectors to produce the proper
combustion chamber mixture.
D
Low HO2S voltage is a lean mixture which will result in
a rich command to compensate.
D
High HO2S voltage is a rich mixture which will result in
a lean command to compensate.