6E–45
3.2L ENGINE DRIVEABILITY AND EMISSIONS
Engine Control Module ECM
Diagnosis
To read and clear diagnostic trouble codes, use a Tech 2.
IMPORTANT:
Use of a Tech 2 is recommended to clear
diagnostic trouble codes from the ECM memory.
Diagnostic trouble codes can also be cleared by turning
the ignition “OFF” and disconnecting the battery power
from the ECM for 30 seconds. Turning off the ignition and
disconnecting the battery power from the ECM will cause
all diagnostic information in the ECM memory to be
cleared. Therefore, all the diagnostic tests will have to be
re-run.
Since the ECM can have a failure which may affect only
one circuit, following the diagnostic procedures in this
section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the ECM connections
or the ECM is the cause of a problem, and the ECM is
replaced, but this does not correct the problem, one of the
following may be the reason:
D
There is a problem with the ECM terminal connections.
The terminals may have to be removed from the
connector in order to check them properly.
D
The problem is intermittent. This means that the
problem is not present at the time the system is being
checked. In this case, refer to the
Symptoms portion of
the manual and make a careful physical inspection of
all components and wiring associated with the affected
system.
D
There is a shorted solenoid, relay coil, or harness.
Solenoids and relays are turned “ON” and “OFF” by the
ECM using internal electronic switches called drivers.
A shorted solenoid, relay coil, or harness will not
damage the ECM but will cause the solenoid or relay to
be inoperative.
Multiple ECM Information Sensor
DTCS Set
Circuit Description
The Engine Control Module ECM monitors various
sensors to determine the engine operating conditions.
The ECM controls fuel delivery, spark advance,
transmission operation, and emission control device
operation based on the sensor inputs.
The ECM provides a sensor ground to all of the sensors.
The ECM applies 5 volts through a pull-up resistor, and
determines the status of the following sensors by
monitoring the voltage present between the 5-volt supply
and the resistor:
D
The engine coolant temperature (ETC) sensor
D
The intake air temperature (IAT) sensor
The ECM provides the following sensors with a 5-volt
reference and a sensor ground signal:
D
The throttle position (TP) sensor
D
The barometric pressure (BARO) sensor
The ECM monitors the separate feedback signals from
these sensors in order to determine their operating
status.
Diagnostic Aids
IMPORTANT:
Be sure to inspect ECM and engine
grounds for being secure and clean.
A short to voltage in one of the sensor input circuits may
cause one or more of the following DTCs to be set:
D
P0108
D
P0113
D
P0118
D
P0123
IMPORTANT:
If a sensor input circuit has been shorted
to voltage, ensure that the sensor is not damaged. A
damaged sensor will continue to indicate a high or low
voltage after the affected circuit has been repaired. If the
sensor has been damaged, replace it.
An open in the sensor ground circuit between the ECM
and the splice will cause one or more of the following
DTCs to be set:
D
P0108
D
P0113
D
P0118
D
P0123
A short to ground in the 5-volt reference A or B circuit will
cause one or more of the following DTCs to be set:
D
P0107
D
P0122
An the in the 5-volt reference circuit A, between the ECM
and the splice will cause one or more of the following
DTCs to be set:
D
P0122
An the in the 5-volt reference circuit B, between the ECM
and the splice will cause one or more of the following
DTCs to be set:
D
P0107
Check for the following conditions:
D
Poor connection at ECM. Inspect the harness
connectors for backed-out terminals, improper mating,
broken locks, improperly formed or damage terminals,
and a poor terminal-to-wire connection.
D
Damaged harness. Inspect the wiring harness for
damage. If the harness is not damaged, observe an
affected sensor’s displayed value on the Tech 2 with
the ignition “ON” and the engine “OFF” while you move
the connectors and the wiring harnesses related to the
following sensors:
D
IAT
D
ECT
D
TP
D
BARO