P251C
PTO Enable Switch Circuit High
The PTO enable switch input reads stuck high — typically a short to battery voltage. The ECM cannot pull the input low, so the switch state is unreadable and PTO mode is locked out for safety.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Switch wire shorted to battery voltageCommon
- Connector pins corroded - high contact resistanceLess likely
- Supply wire pinched against B+ sourceLess likely
Parts involved
- Pto Enable Switch
- Wiring Harness
P251C is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.