Manifold Absolute Pressure Sensor (Metro)

A malfunction in MAP sensor circuit can set a related DTC. For test procedure with DTC set, see appropriate SELF-DIAGNOSTICS article. Use the following procedure to diagnose MAP sensor. If driveability problems exist, MAP sensor failure is suspected, and no DTCs are set, disconnect MAP sensor connector. If driveability improves, replace MAP sensor.

1. Locate and remove MAP sensor. See MANIFOLD ABSOLUTE PRESSURE SENSOR LOCATION  table. Turn ignition on. Using DVOM, measure reference voltage from PCM to MAP sensor. See WIRING DIAGRAMS article. Voltage should be about 5 volts.
2. Disconnect vacuum hose at MAP sensor. Install a hand-held vacuum pump. Turn ignition on. Check signal voltage at MAP sensor. See WIRING DIAGRAMS article.
3. Apply vacuum and note change in signal voltage. As vacuum reading changes, signal voltage should change. Reading should be about 1.0-1.5 volts at high vacuum (idle position), or 4.0-4.5 volts at low vacuum (full throttle position).