Nubira CDX Wagon L4-2.0L DOHC D-TEC MFI (2000)
PCM/ECM controls fuel delivery, spark advance, transaxle operation, and emission control device operation based on the sensor inputs.
The PCM/ECM provides a sensor ground to all of the sensors. The PCM/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,
and the Transmission Fluid Temperature (TFT) sensor. The PCM/ECM provides the Exhaust Gas Recirculation (EGR) Pintle Position Sensor, the
Throttle Position (TP) sensor, the Manifold Absolute Pressure (MAP) sensor, the Air Conditioning Temperature (A)sensor and the Fuel Tank Pressure
Sensor with a 5 volt reference and a sensor ground signal. The PCM/ECM monitors the separate feedback signals from these sensors to determine their
operating status.
Diagnostic Aids
Be sure to inspect PCM/ECM and 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 Diagnostic Trouble Codes (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 PCM/ 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 PCM/ 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 PCM/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.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The Powertrain On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame
and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The
information is then stored on the scan tool for later reference.
9. A faulty EGR valve can leak a small amount of current from the ignition feed circuit to the 5 volt reference circuit. If the problem does not exist
with the EGR valve disconnected, replace the EGR valve.
11-19.If a sensor input circuit has been shorted to voltage, ensure that the sensor has not been damaged. A damaged IAT or ECT sensor will
continue to indicate a high voltage or low temperature after the affected circuit has been repaired. A damaged ACT, TP, MAP, Fuel Tank
Pressure, or EGR Pintle Position sensor will indicate a high or low voltage or may be stuck at a fixed value after the affected circuit has been
repaired. If the sensor has been damaged, replace it.
21. The replacement PCM/ECM must be reprogrammed. Refer to the latest Techline procedure for PCM/ECM reprogramming.
