Faulty Starter/Generator Coolant Pump
Starter/Generator Coolant Pump harness is open or shorted
Starter/Generator Coolant Pump circuit poor electrical connection
Faulty Starter/Generator Control Module
Engine Light ON (or Service Engine Soon Warning Light)
The Starter/Generator Control Module coolant pump is a single speed ON/OFF pump that circulates coolant through the auxiliary radiator and the starter/generator to control the temperature of the starter/generator. The starter/generator cooling system is separate from the engine cooling system and does not share any coolant or components. The Starter/Generator Control Module coolant pump is controlled by the starter/generator coolant pump relay. This relay is a printed circuit board relay and integrated as part of the underhood fuse block. The relay switch and coil both receive B+. The Starter/Generator Control Module controls the relay coil by applying ground to the coil control circuit. With the coil grounded, the relay switch is closed and voltage is sent to the Starter/Generator Control Module coolant pump, which will begin circulating coolant.
The Starter/Generator Control Module uses the exponentially weighted moving average to calculate temperature fluctuations in the starter/generator cooling system. In addition, this diagnostic compares the temperature rate of change by a slope calculation within a set time when the Starter/Generator Control Module coolant pump turns ON. This diagnostic runs once after pump turns ON. If the temperature changes over time too quickly, the Starter/Generator Control Module will indicate a fault.