Leganza CDX L4-2.2L DOHC D-TEC MFI (1999)
Powertrain Control Module (PCM)/ Engine Control Module (ECM): Testing and Inspection
Multiple PCM/ECM Information Sensor DTCS Set
Multiple ECM Information Sensor DTCs Set
Circuit Description
The engine control module (ECM) monitors various sensors to determine engine operating conditions. The ECM controls fuel delivery, spark advance,
transaxle 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 monitors the voltage present between
the sensor and the resistor to determine the status of the Engine Coolant Temperature (ECT) sensor, the Intake Air Temperature (IAT) sensor. The ECM
provides the Exhaust Gas Recirculation (EGR) Pintle Position Sensor, the Throttle Position (TP) sensor, the Manifold Absolute Pressure (MAP) sensor,
and the Fuel Tank Pressure Sensor with a 5 volt reference and a sensor ground signal. The ECM monitors the separate feedback signals from these
sensors to determine their operating status.
Diagnostic Aids
Be sure to inspect the ECM and the engine grounds for being secure and clean.
A short to voltage in one of the sensor circuits can cause one or more of the following DTCs to be set: P0108, P0113, P0118, P0123, P1106, P1111,
P1115, P1121, P1625.
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: P0108, P0113, P0118,
P0123, P1106, P1111, P1115, P1121.
A short to ground in the 5 volt reference circuit or an open in the 5 volt reference circuit between the ECM and the splice will cause one or more of the
following DTCs to be set: P0107, P0112, P0117, P0122, P1107, P1112, P1114, P1122.
Check for the following conditions:
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Inspect for a poor connection at the ECM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed
or damaged terminals, and poor terminal-to-wire connection.
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Inspect the wiring harness for damage. If the harness appears to be OK, observe an affected sensor's displayed value on the scan tool with the
ignition ON and the engine OFF while moving connectors and wiring harnesses related to the affected sensors. A change in the affected sensor's
displayed value will indicate the location of the fault.
