The Gravity Sensing Rough Road (G) sensor is a verticallow g-acceleration sensor. By sensing vertical accelerationcaused by bumps or potholes in the road, theEngine Control Module (ECM) can determine if thechanges in crankshaft speed are due to engine misfireor are driveline induced. If the G sensor detects a roughroad condition, the ECM misfire detection diagnostic willbe de-activated. The G sensor at rest output should bebetween 2.35-2.65 volts (+1G). During a rough roadcondition, the voltage output can vary between 0.5(-1G) and 4.5 volts (+3G).

Check for the following conditions:

Since the G sensor shares the ECM 5 volt reference andground terminals with the A/C Pressure Sensor, a damagedA/C Pressure Sensor harness or sensor couldcause a G sensor DTC to set. Refer to "Multiple ECM Information Sensor DTCs Set" in this section.

The G sensor will give correct voltages only if it is level and mounted securely to its bracket.

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

The number(s) below refer to step(s) on the diagnostic table.

The Rough Road (G) sensor is a vertical low g-accelerationsensor. By sensing vertical acceleration caused bybumps or potholes in the road, the Engine Control Module(ECM) can determine if the changes in crankshaftspeed are due to engine misfire or are driveline induced.If the G sensor detects a rough road condition, the ECMmisfire detection diagnostic will be de-activated. The Gsensor at rest output should be between 2.35-2.65 volts(+1G). During a rough road condition, the voltage outputcan vary between 0.5 (-1G) and 4.5 volts (+3G).

Check for the following conditions:

Since the G sensor shares the ECM 5 volt reference and ground terminals with the A/C Pressure Sensor, a damaged A/C Pressure Sensor harness or sensor could cause a G sensor DTC to set. Refer to "Multiple ECM Information Sensor DTCs Set" in this section.

The G sensor will give correct voltages only if it is level and mounted securely to its bracket.

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

The number(s) below refer to step(s) on the diagnostic table.

The engine control module (ECM) identifies engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when a vehicle is operated over a rough road. The Anti-Lock Brake System (ABS) can detect if the vehicle is on a rough surface based on wheel acceleration/deceleration data supplied by each wheel speed sensor. This information is sent to the ECM by the Electronic Brake Control Module (EBCM) through the Instrument Panel Cluster (IPC) over the Universal Asynchronous Receiver Transmitter (UART) serial data line. The ECM then uses this information to determine if the crankshaft variations are being caused by an actual engine misfire or from being driven on a rough surface.

If the ABS is found to be malfunctioning, the ECM will still continue to detect for misfire. However, if a misfire Diagnostic Trouble Code (DTC) is set, this additional DTC will also be set, indicating that rough surface data was not usable during the misfire detection due to the ABS malfunction.

The setting of this DTC indicates that a misfire was detected and that the ECM could not determine if the detected misfire was true or due to operating the vehicle on a rough surface. A misfire can be a true misfire with or without setting this DTC. Check the IPC and the EBCM for poor connections at the UART serial data terminals. Be sure no true misfire exists after repairing the cause of this DTC.

The number(s) below refer to step(s) on the diagnostic table.

The engine control module (ECM) identifies engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when a vehicle is operated over a rough road. The Anti-Lock Brake System (ABS) can detect if the vehicle is on a rough surface based on wheel acceleration/deceleration data supplied by each wheel speed sensor. This information is sent to the ECM by the Electronic Brake Control Module EBCM through the Instrument Panel Cluster (IPC) over the Universal Asynchronous Receiver Transmitter (UART) serial data line. The ECM then uses this information to determine if the crankshaft variations are being caused by an actual engine misfire or from being driven on a rough surface.

If the ABS is found to be malfunctioning, the ECM will still continue to detect for misfire. However, if a misfire Diagnostic Trouble Code (DTC) is set, this additional DTC will also be set, indicating that rough surface data was not usable during the misfire detection due to the ABS malfunction.

The setting of this DTC indicates that a misfire was detected and that the ECM could not determine if the detected misfire was true or due to operating the vehicle on a rough surface. A misfire can be a true misfire with or without setting this DTC. Check the IPC and the EBCM for poor connections at the UART serial data terminals. Be sure no true misfire exists after repairing the cause of this DTC.

The number(s) below refer to step(s) on the diagnostic table.

The Engine Control Module (ECM) is the control center of the fuel injection system. It constantly looks at the information from various sensors, and controls the systems that affect vehicle performance. The ECM also performs the diagnostic function of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL) (Check Engine), and store a Diagnostic Trouble Code (DTC) or DTCs which identify the problem areas to aid the technician in making repairs. The ECM received incorrect message identification.

The Engine Control Module (ECM) supplies a voltage of about 0.45 volts between terminals M12 and M29 (if measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volts). The Front Heated Oxygen Sensor (HO2S1) varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volts if the exhaust is lean.

In internal circuitry of the Engine control Module (ECM) can identify if the vehicle fuel system is capable of cutoff amount of the fuel supply during deceleration. When a Decel Fuel Cutoff (DFCO) mode of operation is requested during Closed Loop operation, the ECM will cutoff the fuel supply to the engine. Under these conditions the ECM should detect a lean condition. If the ECM detect a rich condition at this time, Diagnostic Trouble Code (DTC) P1167 will set. Damaged fuel pressure regulator and faulty injector will be the cause of this DTC.

The DTC P2297 or rich exhaust is most likely caused by one of the following items:

The Engine Control Module (ECM) is the control centerof the fuel injection system. It constantly looks at the informationfrom various sensors, and controls the systemsthat affect vehicle performance. The ECM alsoperforms the diagnostic function of the system. It canrecognize operational problems, alert the driver throughthe Malfunction Indicator Lamp (MIL) (Check Engine),and store a Diagnostic Trouble Code (DTC) or DTCswhich identify the problem areas to aid the technician inmaking repairs. An Electrically Erasable ProgrammableRead Only Memory (EEPROM) is used to house theprogram information and the calibrations required forengine, transmission, and powertrain diagnostics operation. The ECM checks operation of Lower Power Counter Integrated Chip (I/C) and communication between main CPU and Lower Power Counter I/C. The ECM also monitors EEPROM reset flag and Lower Power Counter I/C overflow bits. If the ECM detects ifLower Power Counter I/C has been reset due to batterydisconnect or Lower Power Counter I/C malfunction, theDiagnostic Trouble Code (DTC) will stored.

(Lower Power Counter Error)

(Lower Power Counter Reset)

The Serial Peripheral Interface (SPI) communication is used internally by the Engine Control Module (ECM) to send message between the engine processor and the automatic transaxle processor. Included in each message sent between the two processor is a checksum of the message. Both the engine processor automatic transaxle processor will compare this checksum value with calculated checksum. If the checksum do not match, the processor will review the new data as being corrupted and ignore the value. The processor then use the previous message. The receiving processor will then send a message to the sending processor informing it that its last message was corrupted.

The ECM monitor periodic TCM status message and if message is not received fail counter incremented and Diagnostic trouble Code (DTC) will stored.

The Engine Control Module (ECM) is the control center of the fuel injection system. It constantly looks at the information from various sensors, and controls the systems that affect vehicle performance. The ECM also performs the diagnostic function of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL) (Check Engine), and store a Diagnostic Trouble Code (DTC) or DTCs which identify the problem areas to aid the technician in making repairs. The ECM detects communication link failure with immobilizer control unit.