Ensure all accessories are off. Using voltmeter, check voltage at ISC valve during cranking and for 10 seconds after engine starts. The ISC valve is located near end of intake chamber on passenger's side.
NOTE: The ISC valve may also be identified by appropriate illustration in THEORY/OPERATION article in the ENGINE PERFORMANCE Section or wire color. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.
If battery voltage exists, proceed to step 3). If battery voltage does not exist, check wiring circuit between Electronic Control Unit (ECU) and ISC valve. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section. The ECU is located at bottom center of dash, in front of console.
Remove ISC valve. Test ISC valve by applying air pressure to designated area and checking air passage, and then applying battery voltage and retesting. See Fig 1. Replace ISC valve if defective.

Fig 1: Checking ISC Valve Operation

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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.

Safety Warning

Idle Speed Control (ISC) System