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. As manifold pressure changes, sensor output voltage also changes. See MANIFOLD PRESSURE VS. SCAN TOOL VOLTAGE  table. By monitoring sensor output voltage, PCM knows the value of 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 for more than 10 seconds, throttle valve is closed, and engine speed is less than 1000 RPM.
• MAP sensor output voltage is less than one volt for more than 5 seconds, TP sensor voltage is at least 1.82 volts, and engine speed is less than 2500 RPM.

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).