NOTE: For more LS400 information, see FUEL SYSTEM CIRCUIT diagnosis chart at end of article. See CIRCUIT DIAGNOSIS CHARTS .

Turn ignition off. Circuit opening relay is located under engine ECU on ES250 and on right side of engine ECU on LS400. Remove relay from vehicle. Using an ohmmeter, check for continuity between relay terminals STA and E1 on ES250 or ST and E1 on LS400. See Fig 1 & 10. Check for continuity between terminals B and FC on ES250 or IG and FC on LS400. Ensure continuity does not exist between terminals B and FP. If continuity is not as specified, replace relay.
Apply battery voltage between terminals STA and E1 on ES250 or ST and E1 on LS400. Using an ohmmeter, ensure continuity is present between terminals B and FP. Apply battery voltage between terminals B and FC on ES250 or IG and FC on LS400. Ensure continuity is present between terminals B and FP. If continuity is not as specified, replace relay.

Fig 1: ES250 Circuit Opening Relay Terminal ID

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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.

Safety Warning

Circuit Opening Relay