Honda 78410-SV4-003 Sensor Assembly, Speed

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The oxygen sensor is fitted into the exhaust manifold to monitor the oxygen content of the exhaust gas stream and thus has a voltage output that fluctuates between 0.1 volts/high oxygen, lean mix and 0.9 volts/low oxygen, rich mix. This variable voltage is exploited by the ECM to regulate the air/fuel mixture ratio as close to the stoichiometric ratio of 14.7 parts air to 1 part fuel so as to reduce emissions and maximize catalytic converter effectiveness. The sensor does not generate voltage below approximately 600 degrees F and during warm up the ECM is in an OPEN LOOP mode. When the engine is at normal temperature and the sensor gives a constant voltage below 0.45 volts at 1,500 rpm or higher, the ECM will set a code 1 with other codes if there are problems with heater circuit. In addition to that, electrical connections, air supply, proper operating temperature of the sensors and the use of unleaded fuel for the car properly must be observed. During servicing particular care should be taken not to damage the pigtail and the electrical connector, and contaminants should not come into contact with the sensor. To check the sensor, backprobe the electrical connector to observe the output voltage; the voltage should vary in the range of 0.1 to 0.9 volts as the engine warms up. To test the oxygen sensor heater it should be checked to ensure that it has the correct resistance and continuity, while check proper supply voltage. If any of the tests do not yield the expected result it is then very advisable to replace the sensor. As for removal, the battery must be disconnected, and the vehicle must be lifted, after which the sensor can be removed, with anti-seize compound applied to the threads prior to reinstallation. MAP stands for Manifold Absolute Pressure, and this sensor's function is to measure intake manifold pressure and change it into voltage for the ECM to determine the volume of fuel and the correct ignition time; if faulty, may trigger Code 3 or 5. Checking is done by inspecting the vacuum hose, electrical connection and voltage signals and replacement is done when the sensor has been disconnected and removed. CKP/TDC and CYP sensors in the distributor control fuel, injection timing and engine RPM where diagnostic tests include those of resistance and continuity. The coolant temperature sensor is a thermistor its voltage output changes with temperature and a faulty one may set code 6. Resistance of the resistance should be measured at cold as well as at the operating conditions of the devices and supply voltage. Throttle position sensor controls throttle valve angle used for fuel supply and needs to be strictly observed for changes in the reference voltage and actual signal voltage as the throttle is increased more. The map sensor and Intake Air Temperature (IAT) sensor's resistance should be tested, as well as reference voltage; another restore procedure is the same as in case with other sensors. Located in the sensor module, the VSS generates a voltage that is proportional to the speed of the vehicle It is tested for voltage and continuity and the replacement of this component involves severing of the given module. The Barometric (BARO) pressure sensors are of the ECM type, and any code should be addressed by a professional only. In the automatic transaxles, the LUC Solenoid operates the lock-up torque converter; an output actuator that is computer-controlled.

Before unplugging or reattaching any electrical connections, ensure the ignition is off.

To remove it, depress the tab to release the electrical connector, disconnect the connector, remove the mounting bolt, and pull the sensor straight up.

Finally, reinstall the wheel and lug nuts, lower the vehicle, and tighten the lug nuts to the specified torque.

The Vehicle Speed Sensor (VSS) is a magnetic pick-up sensor that sends a signal to the Powertrain Control Module (PCM) and the speedometer.

After connecting the wiring, the ABS checker should be used to verify the signal from the wheel speed sensor.