B1750
Park/Neutral Switch Circuit Open
Body Transmission Control Park/Neutral Detection 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The ECU can't detect whether your transmission is in Park or Neutral because the switch circuit has an open connection—like a broken light switch that won't complete the electrical circuit. This prevents the engine from starting or causes shifting issues.

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Symptoms You May Notice
3 known symptoms for this code
Engine won't start or hard to start
Transmission won't shift out of Park
Check Engine Light illuminated
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors voltage on the Park/Neutral switch circuit to confirm transmission position before allowing starter engagement. An open circuit creates an abnormal voltage state (no continuity detected) rather than the expected low or high signal. The ECU sets a fault code when this signal remains outside normal parameters.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Park/Neutral Switch Signal 0V (Park) or 5V (Neutral) with continuity Open circuit / no continuity detected
Circuit Resistance Less than 10 ohms when engaged Greater than 100 ohms or infinite resistance
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Park/Neutral switch connector
Inspect and reseat the connector at the transmission; corrosion or loose pins often cause open circuits.
2
Wiring harness
Check for damaged, pinched, or corroded wires between switch and ECU; repair or replace as needed.
3
Park/Neutral switch
Replace the switch if connector and wiring are intact; internal contacts wear out over time.