1990 Lexus ES 250 AutomaticFACTORY OEM SERVICE PROCEDURE

Cooling Fan System

  1. With coolant temperature less than 185°F (85°C), turn ignition on. Cooling fans should not rotate. If cooling fans rotate, check cooling fan relays and water temperature sensor. Check for damaged connectors or an open circuit between cooling fan relay and water temperature sensor.
  2. Disconnect water temperature sensor connector. See Fig 1. With ignition on, cooling fans should operate. If cooling fans do not operate, check cooling fan relays and water temperature sensor. Check for damaged connectors or an open circuit between cooling fan relay and water temperature sensor.
    Fig 1: Locating ES250 Cooling Fan System Components
    G90F18866Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Start engine. Warm engine to operating temperature. Cooling fans should operate at low speed. If cooling fans do not operate at low speed, replace water temperature sensor.
  4. Warm engine to more than 194°F (90°C). Cooling fans should operate at high speed. If cooling fans do not operate at high speed, replace water temperature sensor.
  5. Turn ignition off. Disconnect the cooling fan ECU. See Fig 1. Using a DVOM, measure resistance and voltage as indicated in the COOLING FAN ECU SPECIFICATIONS  table. Make all measurements from harness side of connector. See Fig 2. Repair harness as necessary.
    COOLING FAN ECU SPECIFICATIONS

    Terminals Condition Value
    2 & Ground N/A Continuity
    3 & Ground Ignition On Battery Voltage
    4 & Ground Ignition On Battery Voltage
    5 & 7 (1) 176°F (80°C) Approx. 1530 Ohms
    5 & 7 (1) 194°F (90°C) Approx. 1180 Ohms
    5 & 7 (1) 203°F (95°C) Approx. 1030 Ohms
    6 & Ground N/A Continuity
    (1) Coolant temperature.
    Fig 2: Identifying ES250 Cooling Fan ECU Harness Terminals
    G90G18867Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  6. Using a DVOM, measure resistance between water temperature sensor terminals. For water temperature sensor location, see Fig 1. See WATER TEMPERATURE SENSOR RESISTANCE  table. If water temperature sensor is not within specification, replace sensor.
    WATER TEMPERATURE SENSOR RESISTANCE

    Temperature Ohms
    176°F (80°C) 1530
    194°F (90°C) 1180
    203°F (95°C) 1030
  7. Disconnect engine main relay. See Fig 1. Using a DVOM, check for continuity between relay terminals No. 1 and 3. See Fig 3. Check for continuity between relay terminals No. 2 and 4. Ensure continuity is not present between relay terminals No. 4 and 5. If DVOM readings are not as specified, replace relay.
    Fig 3: Identifying ES250 Engine Main Relay Terminals
    G90H18868Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  8. Apply battery voltage between relay terminals No. 1 and 3. Using a DVOM, check for continuity between relay terminals No. 4 and 5. Ensure continuity is not present between relay terminals No. 2 and 4. If DVOM readings are not as specified, replace relay.
  9. Disconnect cooling fan relay No. 1. See Fig 4. Using a DVOM, check for continuity between relay terminals No. 1 and 2. See Fig 4. Check for continuity between relay terminals No. 3 and 4. If continuity is not as specified, replace cooling fan relay No. 1.
    Fig 4: Identifying ES250 Cooling Fan Relay No. 1 Terminals
    G90I18869Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  10. Apply battery voltage between relay terminals No. 1 and 2. Using a DVOM, ensure continuity is not present between relay terminals No. 3 and 4. If continuity is present, replace relay.
  11. Disconnect cooling fan relay No. 2. See Fig 1. Using a DVOM, check for continuity between relay terminals No. 2 and 6. See Fig 5. Check for continuity between relay terminals No. 1 and 3. Ensure continuity is not present between relay terminals No. 1 and 4. If continuity reading are not as specified, replace relay.
    Fig 5: Identifying ES250 Cooling Fan Relay No. 2 Terminals
    G90B18870Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  12. Apply battery voltage between relay terminals No. 2 and 6. Using a DVOM, check for continuity between relay terminals No. 1 and 3. Check for continuity between terminals No. 1 and 4. If continuity is not as specified, replace relay.
  13. Remove cooling fan relay No. 3. See Fig 1. Using a DVOM, check for continuity between relay terminals No. 1 and 3. See Fig 6. Ensure continuity is not present between terminals No. 2 and 4. If continuity is not as specified, replace relay.
    Fig 6: ES250 Cooling Fan Relay No. 3 & EFI Main Relay Terminals
    G90C18871Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  14. Apply battery voltage between relay terminals No. 1 and 3. Using a DVOM, check for continuity between terminals No. 2 and 4. If continuity is not as specified, replace relay.
  15. Disconnect cooling fan electrical connector. Connect vehicle battery with an ammeter in series to cooling fan connector. See Fig 7. Ensure cooling fans operate smoothly. Ammeter reading should not exceed specifications in COOLING FAN AMPERAGE  table.
COOLING FAN AMPERAGE

Application Amps
Cooling Fan No. 1 12.1-15.1
Cooling Fan No. 2 6.0-7.4
Fig 7: Connecting ES250 Battery To Cooling Fan
G90D18872Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.