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 P0105 will set when MAP sensor output is zero kPa, or MAP sensor output is 130 kPa or greater with ignition on.

When DTC sets, MIL will illuminate. 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) and ignition timing fixed value of 5 degrees BTDC.