Theory Of Operation

WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.

The Purpose of the Electric Coolant After-run Pump is to reduce heat soak in the Turbocharger after the engine is shut down. The Powertrain Control Module accomplishes this by latching the ASD Relay, and then grounding the Electric Coolant Pump Relay Control circuit to close the relay. Battery voltage is supplied to the Electric Coolant Pump motor via the Electric Coolant Pump Output circuit. The motor is grounded through a dedicated ground circuit.

The PCM monitors the performance of the output voltage and pump via the Electric Coolant Pump Signal circuit. Voltage passes through a bridge on the motor windings and back to the PCM on the signal circuit. If the feedback voltage on the signal circuit is above 3.5 volts when the PCM has commanded the pump on, it is determined that the relay closed and voltage output supply is present.

The PCM also monitors the performance of the pump motor and ground circuit. The PCM looks for a calculated ripple in the feedback voltage when the pump is commanded on. If the PCM does not see a ripple in the voltage feedback when the pump motor is commanded on, then it is determined that there is an open in the ground circuit or the pump motor windings.