Probable Causes:

• A/C Switch or Switch Circuit
• Accelerator Pedal or Cable
• Neutral/Start Switch or Switch Circuit
• Throttle Position Sensor IDL Circuit
• ECM

To check throttle position sensor circuit, see Code 41.

To check A/C switch signal, use the following procedure.

Fig 1: Code 51 Flow Chart - Switch Condition Signal

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Fig 2: Code 51 Schematic - Switch Condition Signal

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