Honda Civic 1992-1995 EG Engine Control Unit (ECU): input devices
06-23-2009, 04:38 PM
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Honda Civic 1992-1995 EG Engine Control Unit (ECU): input devices
To see the original article with images check it out here: Engine Control Unit (ECU). Garage411.com
Computerized engine controls are used to control fuel, ignition and emission control systems. Engine Control Unit (ECU) receives input signals from various sensors and components. ECU then compares each signal with a preprogrammed parameter in its memory. Based on this comparison, output signals are then adjusted to allow vehicle to perform optimally under all operating conditions. ECU is located under passenger-side carpet on Accord and Prelude. On Civic and Civic Del Sol, ECU is located behind passenger-side kick panel.
FYI: Components are grouped into 2 categories. First category covers INPUT DEVICES, which control or produce voltage signals monitored by ECM. Second category is OUTPUT SIGNALS, which are components controlled by ECM.
INPUT DEVICES
Vehicles are equipped with different combination of input devices. Not all devices are used on all models. To determine component usage of a specific model, see appropriate wiring diagrams. Available input signals include the following:
AC Switch Signal
This switch signals ECM of demand for air conditioning. ECM then increases engine RPM to compensate for additional engine load.
Alternator (FR) Signal
This signals ECM when alternator field circuit is energized. ECM compensates for changes in idle speed and low battery voltage which can cause erratic injector pulse width.
Automatic Transmission Shift Position Signal
This signals ECM when transmission selector lever is in Park, Neutral or D4 position.
Barometric Pressure (BARO) Sensor
BARO sensor converts barometric (atmospheric) pressure into electrical signals and relays information to ECM.
Battery Voltage (IGN.1)
This provides ECM with battery voltage signal from ignition circuit when ignition is on.
Brake Switch Signal
This signals ECM when brake pedal is depressed.
Electric Load Detector (ELD)
This signals ECM when an electrical load (headlights, radio, etc.) exists so ECM can compensate for additional engine load.
Engine Coolant Temperature (ECT) Sensor
Coolant temperature sensor is a temperature-dependent variable resistor (thermistor). Resistance of thermistor decreases as coolant temperature increases.
Exhaust Gas Recirculation Valve Lift Sensor
EGR valve lift sensor detects amount of EGR valve lift and sends information to ECM. ECM uses this information, along with other sensor inputs, to determine regulation of EGR control solenoid valve.
Intake Air Temperature (IAT) Sensor
Intake air temperature sensor is a temperature-dependent variable resistor (thermistor). Thermistor resistance decreases as intake air temperature increases.
Manifold Absolute Pressure (MAP) Sensor
MAP sensor converts manifold absolute pressure into electrical signals and sends signals to ECM. MAP sensor signals are a measurement of engine load.
Manual Transmission Clutch Switch (Civic)
Switch is mounted above clutch pedal. Switch signals ECM when clutch is engaged to provide for idle speed adjustment.
Oxygen Sensor (O2S)
Oxygen sensor detects oxygen content of exhaust gases and sends signal to ECM, which varies air/fuel ratio to maintain a 14.7:1 ratio under most conditions. This ratio is most efficient for combustion and catalytic converter operation.
All models except Civic with D15Z1 engine use heated oxygen sensors. Civic with D15Z1 engine uses a heated linear air/fuel ratio type oxygen sensor which performs the same function as standard oxygen sensor, but over a wider range.
Power Steering Pressure Switch
This switch signals ECM when power steering load is high. ECM then compensates for load by increasing engine RPM.
Starter Signal
Signals ECM when engine is cranking.
TDC/CKP/CYP Sensor
TDC/CKP/CYP sensor is a combination sensor located inside distributor. Each sensor generates a separate signal. CKP sensor detects engine RPM to determine fuel injection timing and ignition of each cylinder. TDC sensor determines ignition timing at start-up (cranking) and detects when crank angle signal is abnormal. CYP sensor detects position of cylinder No. 1 for sequential fuel injection to each cylinder.
Throttle Position (TP) Sensor
TP sensor is a 3-wire potentiometer connected to throttle shaft. As throttle position changes, TP sensor varies voltage signal monitored by ECM. Sensor voltage ranges from about one volt at closed throttle to about 5 volts at wide open throttle.
Valve Timing Oil Pressure Switch
Located on Variable Valve Timing Electronic Control (VTEC) spool valve, switch signals ECM when VTEC system is operating. Switch will set a code in case of failure in circuit.
Vehicle Speed Sensor/Pulser (VSS)
Vehicle speed signal is generated by speed sensor (sometimes called a speed pulser), which produces 4 pulses (switch grounded) per speedometer cable revolution.
To see the original article with images check it out here: Engine Control Unit (ECU). Garage411.com
Computerized engine controls are used to control fuel, ignition and emission control systems. Engine Control Unit (ECU) receives input signals from various sensors and components. ECU then compares each signal with a preprogrammed parameter in its memory. Based on this comparison, output signals are then adjusted to allow vehicle to perform optimally under all operating conditions. ECU is located under passenger-side carpet on Accord and Prelude. On Civic and Civic Del Sol, ECU is located behind passenger-side kick panel.
FYI: Components are grouped into 2 categories. First category covers INPUT DEVICES, which control or produce voltage signals monitored by ECM. Second category is OUTPUT SIGNALS, which are components controlled by ECM.
INPUT DEVICES
Vehicles are equipped with different combination of input devices. Not all devices are used on all models. To determine component usage of a specific model, see appropriate wiring diagrams. Available input signals include the following:
AC Switch Signal
This switch signals ECM of demand for air conditioning. ECM then increases engine RPM to compensate for additional engine load.
Alternator (FR) Signal
This signals ECM when alternator field circuit is energized. ECM compensates for changes in idle speed and low battery voltage which can cause erratic injector pulse width.
Automatic Transmission Shift Position Signal
This signals ECM when transmission selector lever is in Park, Neutral or D4 position.
Barometric Pressure (BARO) Sensor
BARO sensor converts barometric (atmospheric) pressure into electrical signals and relays information to ECM.
Battery Voltage (IGN.1)
This provides ECM with battery voltage signal from ignition circuit when ignition is on.
Brake Switch Signal
This signals ECM when brake pedal is depressed.
Electric Load Detector (ELD)
This signals ECM when an electrical load (headlights, radio, etc.) exists so ECM can compensate for additional engine load.
Engine Coolant Temperature (ECT) Sensor
Coolant temperature sensor is a temperature-dependent variable resistor (thermistor). Resistance of thermistor decreases as coolant temperature increases.
Exhaust Gas Recirculation Valve Lift Sensor
EGR valve lift sensor detects amount of EGR valve lift and sends information to ECM. ECM uses this information, along with other sensor inputs, to determine regulation of EGR control solenoid valve.
Intake Air Temperature (IAT) Sensor
Intake air temperature sensor is a temperature-dependent variable resistor (thermistor). Thermistor resistance decreases as intake air temperature increases.
Manifold Absolute Pressure (MAP) Sensor
MAP sensor converts manifold absolute pressure into electrical signals and sends signals to ECM. MAP sensor signals are a measurement of engine load.
Manual Transmission Clutch Switch (Civic)
Switch is mounted above clutch pedal. Switch signals ECM when clutch is engaged to provide for idle speed adjustment.
Oxygen Sensor (O2S)
Oxygen sensor detects oxygen content of exhaust gases and sends signal to ECM, which varies air/fuel ratio to maintain a 14.7:1 ratio under most conditions. This ratio is most efficient for combustion and catalytic converter operation.
All models except Civic with D15Z1 engine use heated oxygen sensors. Civic with D15Z1 engine uses a heated linear air/fuel ratio type oxygen sensor which performs the same function as standard oxygen sensor, but over a wider range.
Power Steering Pressure Switch
This switch signals ECM when power steering load is high. ECM then compensates for load by increasing engine RPM.
Starter Signal
Signals ECM when engine is cranking.
TDC/CKP/CYP Sensor
TDC/CKP/CYP sensor is a combination sensor located inside distributor. Each sensor generates a separate signal. CKP sensor detects engine RPM to determine fuel injection timing and ignition of each cylinder. TDC sensor determines ignition timing at start-up (cranking) and detects when crank angle signal is abnormal. CYP sensor detects position of cylinder No. 1 for sequential fuel injection to each cylinder.
Throttle Position (TP) Sensor
TP sensor is a 3-wire potentiometer connected to throttle shaft. As throttle position changes, TP sensor varies voltage signal monitored by ECM. Sensor voltage ranges from about one volt at closed throttle to about 5 volts at wide open throttle.
Valve Timing Oil Pressure Switch
Located on Variable Valve Timing Electronic Control (VTEC) spool valve, switch signals ECM when VTEC system is operating. Switch will set a code in case of failure in circuit.
Vehicle Speed Sensor/Pulser (VSS)
Vehicle speed signal is generated by speed sensor (sometimes called a speed pulser), which produces 4 pulses (switch grounded) per speedometer cable revolution.
To see the original article with images check it out here: Engine Control Unit (ECU). Garage411.com
Last edited by Master23; 07-01-2009 at 05:26 PM.
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