Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Heater Pump
The heater pump is required to maintain engine coolant flow to the heater core for passenger compartment heating, when the engine is not running. The PCM commands the heater pump ON by energizing the heater pump control relay (HPCR).
The pump is commanded on when the following conditions are met:
- The key is in ON/START position.
- The engine coolant temperature is above a minimum threshold 0°C (32°F) nominal.
- The inferred ambient temperature is below a calibrated value 32°C (90°F) nominal.
- The engine speed is below a calibrated threshold (nominal 4,000 RPM) including engine OFF.
- The climate control mode switch is in any position other than OFF.
The pump is off when the climate control mode switch is set to OFF.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.