Circuit/System Description

WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

The drive motor generator power inverter module (PIM) contains two motor control modules (MCM). Each MCM controls and monitors its respective drive motor generator based upon commands from the hybrid powertrain control module (HPCM). In order for the HPCM to monitor the internal combustion engine speed, MCM 1 is electrically connected to the crankshaft position sensor (CKP) signal and reference circuits. The MCM 1 engine speed information is broadcast to the HPCM over an internal PIM communication circuit. Additionally, the HPCM receives a GM LAN engine speed that is broadcast by the engine control module (ECM) and is based upon the ECM connection to the CKP sensor.

A drive motor generator position sensor is monitored by each motor control module (MCM). Each MCM monitors the angular position, speed and direction of its respective drive motor generator based upon the signals of the resolver-type position sensor.

The HPCM mathematically calculates what engine speed should be based upon the current transmission ratio and the drive motor generator speeds indicated by the drive motor generator position sensors.

The HPCM compares this mathematically calculated engine speed to the sensor-derived GM LAN ECM engine speed signal and MCM CKP signal engine speed. If the drive motor generator position sensor speeds are correct, the mathematical equation should accurately calculate engine speed. If the mathematical calculation for engine speed does not match the sensor-derived engine speed, a drive motor position speed sensor error is assumed and this DTC will set.