Park/Neutral Switch Input Circuit Low

Where it lives

For P0851, the circuit described runs through the switch. The description of P0851 reports a fault at the switch.

Check these first

• A short to ground in the park/neutral input wire
• Dirty park/neutral switch contacts
• Water in the park/neutral connector
• A poor park/neutral switch ground

What to do next

1. Read park/neutral input voltage
2. Test the input wire for a short to ground
3. Clean the switch contacts
4. Check the switch ground
5. Replace the switch if the signal stays low
6. Clear the code and retest

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