2003 Toyota PriusFACTORY OEM SERVICE PROCEDURE

HV Battery Cooling: Inspection

  1. INSPECT BLOWER MOTOR OPERATION (See  DTC P3077: BATTERY COOLING FAN MOTOR CIRCUIT MALFUNCTION  ) 
  2. INSPECT BATTERY FAN RELAY 
    1. Remove the battery fan relay.
      Fig 1: Removing Battery Fan Relay
      G03431002Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Inspect the battery fan relay continuity.
      1. Using an ohmmeter, check that there is continuity between terminals 1 and 2.

        If there is no continuity, replace the relay.

      2. Check that there is no continuity between terminals 3 and 5.
      Fig 2: Inspecting Battery Fan Relay Continuity Using Ohmmeter
      G03431003Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      If there is continuity, replace the relay.

    3. Inspect the battery fan relay operation.
      1. Apply battery voltage across terminals 1 and 2.
      2. Using an ohmmeter, check that there is continuity between terminals 3 and 5.

      If there is no continuity, replace the relay.

      Fig 3: Checking Continuity Between Terminals 3 & 5
      G03431004Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Install the battery fan relay.
Factory Service Tools

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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.