2010 Cadillac Truck Escalade RWD V8-6.2L Page 1531
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. The MCM monitors the LOI voltage measuring circuitry for correct operation.
Conditions for Running the DTC
* The control module runs the program to detect an internal fault when the key is ON.
* Ignition voltage is 8-18 volts.
Conditions for Setting the DTC
P1AF4 and P1AF6
The motor control module (MCM) detects isolation sensor voltage less than 0V.
P1AF5 and P1AF7
The MCM detects isolation sensor voltage greater than 564V.
Action Taken When the DTC Sets
* DTCs P1AF4, P1AF5, P1AF6 and P1AF7 are Type B DTCs.
* 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
DTCs P1AF4, P1AF5, P1AF6 and P1AF7 are Type B DTCs.
Reference Information
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Circuit/System Verification
Important: DTC P1AE7 must test and pass before performing this diagnostic procedure.
1. Inspect for DTC P1AE7.
瀚慖f the DTC has set, a loss of isolation condition within the hybrid battery has caused this DTC to set. Refer to DTC P1AE6 or P1AE7 (
See: P Code Charts/P1AE6).
2. Clear the DTC information.
3. Turn the ignition OFF for 1 minute.
4. Turn the ignition ON.
5. Retest for DTCs P1AF4, P1AF5, P1AF6 and P1AF7.
Circuit/System Testing
Important: DTC P1AE7 must test and pass before performing this diagnostic procedure.
1. Inspect for DTC P1AE7.
瀚慖f the DTC has set, a loss of isolation condition within the hybrid battery has caused this DTC to set. Refer to DTC P1AE6 or P1AE7 (
See: P Code Charts/P1AE6).
2. Ignition ON, retest for DTCs P1AF4, P1AF5, P1AF6 and P1AF7.
瀚慖f the DTC resets, program the PIM with the latest software version and recheck for DTCs. If the DTC resets after programming or if the
PIM already contains the latest software version, replace the PIM.
