Engine Idle Speed Selector Sensor/Switch Circuit/Open
The idle-speed selector input is open. On commercial vehicles this switch lets the operator pick a fast-idle setpoint (for example to keep auxiliary loads supplied). With the input broken, the ECM cannot apply an operator-selected idle speed.
Affected components
- Idle speed selector switch
- Wiring harness
Common causes
- High likelihood: Open wire or unplugged switch
- Low likelihood: Pin pushed back out of connector body
- Low likelihood: Cracked solder joint inside the module or sensor
Possible symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
Diagnostic notes
- The malfunction indicator lamp may illuminate
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.