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Home >> Mazda >> 1999 >> B2500 SX, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Engine Controls - Self-Diagnostics - EEC-V - 6.8L (99S E Series & 99S F350 To F550)) >> System Tests >> Test TJ: Output Shaft Speed (OSS) Sensor >> Diagnostic Aids

Diagnostic Aids

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Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:

  1. 1) DTC P0720, P0721, P0722, P0723 & P1900: Verify Drive Cycle

    Using scan tool, select OSS PID from PID/DATA monitor menu. Road test vehicle and observe PID value. Shift transmission through all gear rangers, shift up and down. If PID value increases and decreases with engine and vehicle speed, go to next step. If PID value does not increase and decrease with engine and vehicle speed, go to step  3.

  2. 2) Visual Inspection

    Turn ignition off. Disconnect OSS sensor connector located on side of transmission. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. If connector is okay, fault is intermittent. Go to TEST Z  and check for intermittent faults.

  3. 3) Check For Short To Power

    Turn ignition on. Measure voltage between OSS terminal at OSS sensor wiring harness connector and chassis ground. See Fig 1. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in OSS circuit.
    Fig 1: Identifying Output Shaft Speed (OSS) Sensor Circuits & Connector Terminals
    G99H02663Courtesy of FORD MOTOR CO.

  4. 4) Check For Open Circuit

    Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Measure resistance of OSS circuit between PCM connector pin No. 84 and OSS terminal at OSS sensor wiring harness connector. Also measure resistance of SIG RTN circuit between PCM connector pin No. 91 and SIG RTN terminal at OSS sensor wiring harness connector. If both resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, repair open in appropriate circuit.

  5. 5) Check For Short To Ground

    Measure resistance between OSS sensor wiring harness connector terminals. Also measure resistance between OSS terminal at OSS sensor wiring harness connector and chassis ground. If both resistance readings are more than 10,000 ohms, go to next step. If any resistance reading is 10,000 ohms or less, repair short circuit.

  6. 6) Check OSS Sensor Resistance

    Measure resistance between OSS sensor terminals. If resistance is 450-750 ohms, replace PCM. If resistance is not 450-750 ohms, replace OSS sensor.
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