Circuit Description

PCM uses MAP sensor signals to control fuel delivery and ignition timing. MAP sensor measures changes in intake manifold pressure (vacuum). PCM sends a 5-volt reference voltage to MAP sensor. Changes in pressure, resulting from engine load and RPM, are converted into an output voltage monitored by PCM. A low MAP sensor output voltage (about 1.0-1.5 volts at idle) indicates low manifold pressure. High MAP sensor output voltage (about 4.5-4.8 volts at wide open throttle), indicates high manifold pressure.

MAP sensor is also used to measure barometric pressure, allowing PCM to make adjustments for changes in altitudes. DTC P0106 will set when:

• MAP sensor output voltage is greater than 3.3 volts, throttle valve is closed, engine speed is less than 1000 RPM, and engine coolant temperature is greater than 158°F (70°C).
• MAP sensor output voltage is less than 1.5 volts, engine speed is less than 2500 RPM, and TP sensor voltage is greater than one volt.

When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault. PCM will record operating conditions at time of failure and information in freeze frame buffer. PCM will enter Fail-Safe Function using MAP sensor value of 6.8 psi (46.7 kPa).