P1AC1 - Starter/Generator Control Module Cooling Fan Relay Control Circuit Low Voltage

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

  • Faulty Starter/Generator Control Module Cooling Fan Relay
  • Starter/Generator Control Module Cooling Fan Relay harness is open or shorted
  • Starter/Generator Control Module Cooling Fan Relay circuit poor electrical connection

Possible symptoms

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

P1ac1 Description

The Starter/Generator Control Module (SGCM) controls the coolant fan operation by applying voltage to the coolant fan relay control circuit with an internal solid state device called a driver. When the SGCM is commanding the relay ON, the voltage of the control circuit should be low, near 0 volts. When the SGCM is commanding the relay OFF, the voltage potential of the control circuit should be high, near 12 volts.

The SGCM monitors the relay control circuits for the following conditions:

- Short to ground

- Short to voltage

An open circuit

If the SGCM detects an improper voltage level on the coolant fan relay control circuit, then DTC P1AC1 or P1AC2 will set and the driver will be disabled.

OBDII Code P1ac1 - Starter/Generator Control Module Cooling Fan Relay Control Circuit Low Voltage - AutoCodes.com

P1AC1 Information for specific makes

  • P1AC1 BUICK Starter/Generator Control Module Cooling Fan Relay Control Circuit Low Voltage
  • P1AC1 CADILLAC Starter/Generator Control Module Cooling Fan Relay Control Circuit Low Voltage
  • P1AC1 CHEVROLET Starter/Generator Control Module Cooling Fan Relay Control Circuit Low Voltage
  • P1AC1 GMC Starter/Generator Control Module Cooling Fan Relay Control Circuit Low Voltage
  • P1AC1 SATURN Starter/Generator Control Module Cooling Fan Relay Control Circuit Low Voltage

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P1AC1 Comments

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