P1A78 - Starter/Generator Control Module Coolant Temperature Sensor 3 Performance

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

  • Faulty Starter/Generator Control Module (SGCM)
  • Starter/Generator Control Module (SGCM) harness is open or shorted
  • Starter/Generator Control Module (SGCM) circuit poor electrical connection

Possible symptoms

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

P1a78 Description

The Starter/Generator Control Module (SGCM) monitors its internal fluid temperature sensors to control the SGCM coolant pump and SGCM cooling fan. The internal fluid temperature sensors of the SGCM are thermistors and are not serviceable. When the internal fluid temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the internal fluid temperatures are hot, the resistances of the sensors are low and the voltage signals are low. The input parameters are not displayed on the scan tool.
OBDII Code P1a78 - Starter/Generator Control Module Coolant Temperature Sensor 3 Performance - AutoCodes.com

P1A78 Information for specific makes

  • P1A78 BUICK Starter/Generator Control Module Coolant Temperature Sensor 3 Performance
  • P1A78 CADILLAC Starter/Generator Control Module Coolant Temperature Sensor 3 Performance
  • P1A78 CHEVROLET Starter/Generator Control Module Coolant Temperature Sensor 3 Performance
  • P1A78 GMC Starter/Generator Control Module Coolant Temperature Sensor 3 Performance
  • P1A78 SATURN Starter/Generator Control Module Coolant Temperature Sensor 3 Performance

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P1A78 Comments

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