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  • P0521 Oil Pressure Rationality

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    DTC P0521: OIL PRESSURE RATIONALITY

    Monitor & Set Conditions

    Oil pressure rationality is monitored with ignition on and engine off. DTC may set if oil pressure is seen with no RPM signal for 30 seconds.

    Possible Causes

    • Oil Pressure Switch
    • Oil Pressure Signal Circuit Open
    • Oil Pressure Signal Circuit Shorted To Ground
    • Low Oil Pressure
    • ECM

    Testing

    1. Turn ignition on with engine off. Using DRBIII(R) scan tool, in INPUTS/OUTPUTS, read oil pressure switch status. If oil pressure switch displays OPEN, go to next step. If oil pressure switch does not display OPEN, go to step 4 .

    2. Turn ignition off. Disconnect oil pressure switch harness connector. Check for poor connection/terminal contact at oil pressure switch harness connector. Repair as necessary. Using DVOM, measure resistance between terminal "C" on oil pressure switch and oil pressure switch body or ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or greater, replace oil pressure switch. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

    3. Ensure ignition is off. Disconnect ECM harness connector. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for poor connection/terminal contact at ECM harness connector. Repair as necessary. Using DVOM, measure resistance of Gray/Black wire between terminal "C" on oil pressure switch and terminal No. 6 at ECM harness connector. If resistance is less than 5 ohms, replace and program ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If resistance is 5 ohms or greater, repair open in Gray/Black wire between oil pressure switch and ECM.

    4. Using DVOM, measure resistance between ground and terminal "C" on oil pressure switch harness connector (Gray/Black wire). If resistance is less than 5 ohms, repair short to ground in Gray/Black wire between oil pressure switch and ECM. If resistance is 5 ohms or greater, go to next step.

    5. Ensure engine oil level is correct. Oil pressure should be checked. Remove engine oil pressure sensor and install mechanical oil pressure gauge. Start engine and allow engine to warm to normal operating temperature. Check oil pressure with engine idling and at 2000 RPM at normal operating temperature. Oil pressure should be at least 10 psi (.7 kg/cm2 ) at idle and at least 30 psi (2.1 kg/cm2 ) at 2000 RPM. If oil pressure is within specification, replace and program ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Install and tighten engine oil pressure sensor to 12 ft. lbs. (16 N.m). If oil pressure is not within specification, repair engine mechanical problem as necessary. Install and tighten engine oil pressure sensor to 12 ft. lbs. (16 N.m).


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