2010 Cadillac Truck Escalade RWD V8-6.2L Page 1521
Transmission/Transaxle/Service and Repair/Overhaul/2ML70 - Automatic Transmission/13. Drive Motor with Generator Assembly Removal
- 2nd Position)
P1AF2
DTC P1AF0 or P1AF2
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P1AF0
- Drive Motor 1 Control Module Hybrid Battery Voltage System Isolation Lost
DTC P1AF2
- Drive Motor 2 Control Module Hybrid Battery Voltage System Isolation Lost
Circuit/System Description
The drive motor generator power inverter control module (PIM) contains two motor control modules (MCMs). Each MCM measures hybrid battery
high voltage (HV) with several internal sensors. The MCMs test for loss of isolation (LOI) between either the HV positive circuit or HV negative
circuit and vehicle chassis. The MCMs test for isolation when the HV contactor relays are closed. The battery energy control module (BECM) only
tests the hybrid battery assembly for HV loss of isolation when the HV contactor relays are open.
MCM LOI is detected through the use of two high-impedance resistors and voltage measuring circuitry. The two resistors are connected in series
between the HV positive and HV negative circuits. The center connection of the two resistors is also connected to vehicle chassis. The MCM then
measures the voltage drop across one of the resistors. Without a loss of isolation, the MCM should measure about half of the high voltage potential.
This is referred to as mid-pack voltage. The Mid-pack voltage value is then doubled by the software and displayed on a scan tool as Motor 1
Isolation Voltage or Motor 2 Isolation Voltage. When a loss of isolation is present, the motor isolation voltage display will indicate voltage that is
more or less than actual hybrid battery high voltage.
Conditions for Running the DTC
* The high voltage contactor relays are closed.
* High voltage is greater than 50 volts.
* Ignition voltage is 8-18 volts.
* DTCs P1AEE, P1AF4, and P1AF5 are not set.
Conditions for Setting the DTC
The ratio between Mid-Pack Voltage and hybrid battery high voltage is less than 0.27 or greater than 1.80.
OR
* Mid-Pack Voltage is less than 35V or greater than 975V.
* Either above condition exists for 5 seconds.
Action Taken When the DTC Sets
DTCs P1AF0 and P1AF2 are Type C DTCs.
Conditions for Clearing the DTC
DTCs P1AF0 and P1AF2 are Type C DTCs.
Reference Information
Schematic Reference
Hybrid Controls Schematics ()
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
