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 Vehicle Control Module (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 required to set DTC are:

• No TP sensor related DTCs.
• Engine running.
• Engine speed changes less than 75 RPM.
• TP angle changes less than 1.5 percent.
• EGR flow changes less than 2 percent.
• Idle air changes less than 4 steps.
• No change in brake switch status.
• No change in clutch status (M/T).
• No change in A/C status and is stabilized for 2 seconds.
• No EGR DTCs.
• Engine speed steady within a range of 400-5000 RPM.