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Home >> GMC >> 1998 >> Yukon RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Automatic Transmission Diagnosis - 4L80-E (Gasoline)) >> Diagnostic Tests >> DTC P0502: Output Shaft Speed (OSS) Sensor Circuit Low Input >> Diagnostic Aids

Diagnostic Aids

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DTC P0502 sets when no vehicle speed is detected at start-off. Check for Electromagnetic Interferences (EMI) induced on OSS sensor circuits. Check VCM connector and transmission 20-pin connector for bent, backed out or broken terminals or misaligned connectors. Inspect for damaged OSS sensor or for damaged output shaft speed sensor rotor teeth. Ensure OSS sensor is aligned correctly and secured to transmission case properly. An incorrect calibration may set DTC P0502. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value changes. First diagnose and clear any engine and TP sensor DTCs that are present, then inspect for any transmission DTCs that may have reset.

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