Cylinder Compression Pressure

Check engine mechanical condition with a compression gauge, vacuum gauge or DRB-III(R). Ensure battery is fully charged and starter motor is in good operating condition. On 2.5L, 3.5L and 5.9L, disconnect ignition coil connector. On 4.7L, remove coil-on-plugs. On all models, clean spark plug recesses with compressed air. Remove all spark plugs. Remove fuel pump relay from Power Distribution Center (PDC). See Fig 1 and Fig 2 or Fig 3 . Install compression gauge. Hold throttle in wide open throttle position. Using a remote starter switch, rotate engine 3 revolutions. Record compression pressure from third revolution. Continue test for remaining cylinders. See COMPRESSION SPECIFICATIONS  table for correct engine compression pressures.

Fig 1: Locating Power Distribution Center

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Fig 2: Identifying Power Distribution Center Components (Dakota)

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Fig 3: Identifying Power Distribution Center Components (Durango)

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