P1A8B - Volt Inverter Temperature High

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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P1A8B Possible Causes

  • Restricted radiator air flow or coolant fans inoperative
  • Restricted power electronics coolant flow or contaminated coolant
  • Inoperative power electronics cooling system water pump
  • Faulty Accessory Power Module (APM)
  • Accessory Power Module (APM) harness is open or shorted
  • Accessory Power Module (APM) circuit poor electrical connection

First diagnose P1A8B code

    Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded terminals.

Cost of diagnosing the P1A8B code

    Labor: 1.0

    The cost of diagnosing the P1A8B code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle's make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.

P1A8B Possible Symptoms

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

P1a8b Description

The Accessory Power Module (APM) controls the energy flowing between the high voltage, 300-volt, direct current (DC) and intermediate voltage, 42-volt, DC to support the Electric Power Steering (EPS). The APM receives a 42-volt enable command from the Hybrid Powertrain Control Module (HPCM) over the high speed hybrid GMLAN communication circuit. APM functions will run only when the APM Enable is active on the high speed hybrid GMLAN communication circuit.

Heat is generated in the 42-volt APM circuit solely through the demand for use of the EPS. The Engine Control Module (ECM) measures the temperature of the Power Electronics Cooling Loop and commands the flow of 2 electrical coolant pumps. The APM transfers heat in the 42-volt circuit to the APM Heat Plate which is then dissipated at the Power Electronics Front End Heat Exchanger.

Based on the severity of an overheat condition in the 42-volt circuit, the APM will make decisions ranging from notification of an over temperature condition to the EPS to completely shutting down the 42-volt power conversion.

OBDII Code P1a8b - Volt Inverter Temperature High - AutoCodes.com

P1A8B More Information

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