Accord 1985-86
1. Disconnect the vacuum hose between the MAP sensor and the throttle from the throttle and plug the hose hole in the throttle. Connect a hand pump to the open end of the vacuum hose.
2. Remove the sensor connector. Connect cable test system (07999-PD6000A or equivalent) between the control unit and the cable connector.
3. Turn on the ignition. Connect the positive probe of the digital voltmeter to terminal C11 of the cable test system and the negative probe to terminal C14. Measure the voltage, it should be between 0.5V at 100mmHg vacuum. and 4.5V at a vacuum of 1200 mm Hg.
4. If the voltage is not correct - check the vacuum hose for leaks and check the wires between the sensor and the control unit for a short circuit. If the wires are ok, replace the sensor.