P1AF0 - Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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Possible causes

  • Faulty Drive Motor 1 Control Module Hybrid/EV Battery
  • Drive Motor 1 Control Module Hybrid/EV Battery harness is open or shorted
  • Drive Motor 1 Control Module Hybrid/EV Battery circuit poor electrical connection

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P1af0 Description

The power inverter module, often referred to as the drive motor generator power inverter module, contains three motor control modules and the hybrid powertrain control module. Two of the motor control modules operate their respective drive motor generator based upon power inverter module commands. The third motor control module controls the auxiliary transmission fluid pump motor. Each motor control module measures hybrid battery high voltage with several internal sensors. The motor control modules test for loss of isolation between either the high-voltage positive circuit or high-voltage negative circuit and vehicle chassis. The motor control modules test for isolation when the high-voltage contactor relays are closed. The hybrid powertrain control module 2 only tests the hybrid battery assembly for high-voltage loss of isolation when the high-voltage contactor relays are open.

Motor control modules' loss of isolation is detected through the use of two high-impedance resistors and voltage measuring circuitry. The two resistors are connected in series between the high- voltage positive and high-voltage negative circuits. The centre connection of the two resistors is also connected to vehicle chassis. The motor control module then measures the voltage drop across one of the resistors. Without a loss of isolation, the motor control module 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.

OBDII Code P1af0 - Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost - AutoCodes.com

P1AF0 Information for specific makes

  • P1AF0 BUICK Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost
  • P1AF0 CADILLAC Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost
  • P1AF0 CHEVROLET Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost
  • P1AF0 GMC Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost
  • P1AF0 SATURN Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost

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