Mechanical Inspection: Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See appropriate COMPRESSION SPECIFICATIONS table. See engine analyzer manual for specific instructions. Ensure battery is fully charged, engine is at normal operating temperature and throttle valve is fully open when checking compression.

Remove Auto Shutdown (ASD) relay to prevent engine from starting when checking compression. ASD relay is located in Power Distribution Center (PDC). For relay location, check label on underside of PDC cover. Once compression test is complete, reinstall ASD relay and use scan tool to clear DTC from PCM. See appropriate SELF-DIAGNOSTICS article for clearing of DTC.