Circuit Description

Engine load is determined using a "speed density" method. This method is calculated using inputs from Manifold Absolute Pressure (MAP) sensor, Crankshaft Position (CKP) sensor, Intake Air Temperature (IAT) sensor and engine RPM. The MAP sensor is the main sensor used to calculate engine load. Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to MAP sensor. As manifold pressure changes, MAP sensor input voltage to PCM varies from less than 2 volts at idle to greater than 4 volts at Wide Open Throttle (WOT). If PCM detects a MAP sensor input voltage that is excessively high, DTC P0108 will be set.

Conditions required to set DTC are:

• No TP sensor DTCs present.
• Engine is running.
• Throttle position is less than 2.7 percent if engine speed is less than 1000 RPM.
• Throttle position is less than 10 percent if engine speed is greater than 1000 RPM.
• MAP sensor indicates manifold absolute pressure greater than 90 kPa for about 10 seconds.