Circuit Description

Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). A 5-volt reference is applied to sensor. A variable resistor moves in relation to manifold pressure and a voltage signal is returned to VCM through MAP signal circuit. Voltage signal varies from 1-1.5 volts at closed throttle (high vacuum) to 4-4.5 volts at wide open throttle (low vacuum). A change in throttle position and engine speed should precede change in MAP. If change does not occur, MAP malfunction is present. VCM utilizes MAP signal and throttle position to determine fuel delivery.

DTC will set when the following conditions are present:

• Engine is running.
• No TP sensor DTCs are set.
• No IAC sensor DTCs are set.
• No EGR DTCs are set.
• Change in engine speed is less than 100 RPM.
• Change in throttle position is less than 1.95 percent.
• Change in EGR flow is less than 5 percent.
• Change in IAC is less than 5 counts.
• No change in brake switch status.
• No change in clutch status (manual transmission).
• No change in power steering switch status.
• No change in A/C clutch status.
• Conditions have stabilized for 2 seconds.
• Conditions are met for 24 consecutive tests in a sample of 100 tests.
• Change in MAP sensor is greater than .18 volt.