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 1.0-1.5 volts at closed throttle (high vacuum) to 4.0-4.5 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.

Conditions for setting DTC are:

• No TP sensor related DTCs.
• Engine running.
• Engine speed changes less than 100 RPM.
• TP angle changes less than 1.95 percent.
• EGR flow changes less than 10 percent.
• Idle air changes less than 100 counts.
• No change in brake switch status.
• No change in clutch status (M/T).
• No change in A/C status.
• No change in power steering switch status.
• Conditions have stabilized for a period of 0.5 second.