2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 1234
Circuit/System Description
The drive motor generator position sensor is monitored by the motor control module (MCM). The MCM monitors the angular position, speed and
direction of the drive motor generator based upon the signals of the resolver-type position sensor. The position sensor, or resolver, contains a drive
coil, two driven coils and an irregular shaped metallic rotor. The metallic rotor is mechanically attached to the shaft of the drive motor generator. At
ignition ON, the MCM outputs a 7 volt ac, 10 kHz excitation signal to the drive coil. The drive coil excitation signal creates a magnetic field
surrounding the two driven coils and the irregular shaped rotor. The MCM then monitors the two driven coil circuits for a return signal. The
position of the irregular shaped metallic rotor causes the magnetically-induced return signals of the driven coils to vary in size and shape. A
comparison of the two driven coil signals allows the MCM to determine the exact position, speed and direction of the drive motor generator. The
position sensor is a non-serviceable part of the drive motor generator.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The MCM detects a degraded motor position sensor signal.
Action Taken When the DTC Sets
* DTC P0A40 is a Type A DTC.
* The hybrid powertrain control module (HPCM) commands the battery energy control module (BECM) to open the high voltage contactor
relays.
Conditions for Clearing the DTC
DTC P0A40 is a Type A DTC.
Diagnostic Aids
* The drive motor generator position sensor circuits operate at very low current. Extreme care must be taken when probing terminals and
manipulating harnesses.
* The sensor circuit loops are twisted pair with each pair covered in a foil shield. The shield circuits outside of the transmission are grounded to
a stud on the drive motor generator power inverter module (PIM) assembly.
* Ensure the drive motor generator position sensor harness shield circuits are properly grounded prior to testing.
Reference Information
Schematic Reference
Hybrid Controls Schematics ()
Connector End View Reference
