What does it mean?
P1539 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Clutch Vacuum Vent Valve Switch Incorrect Signal .
Symptoms
- Check engine light on with cruise control not working
- Cruise control will not engage, or does not cancel when the clutch is pressed
- Idle flares or dips during gear changes
- Occasional stalling when the clutch is depressed at low speed
- Cruise indicator lamp stays off
- Otherwise normal engine performance
Likely causes
- Switch out of adjustment, so it does not change state at the correct point of pedal travel
- Worn or sticking switch contacts
- Cracked or disconnected vacuum line at the vent valve
- Broken or bent pedal bracket, striker or return spring
- Corroded connector and chafed wiring in the pedal box area
- Wiring damaged by items placed in the driver footwell or by water entering there
- Module input circuit failure as the last suspect
How to fix it
- Watch the clutch switch input in live data while slowly pressing and releasing the pedal
- Check the switch adjustment against the pedal stop and reset it to the specified travel
- Inspect the vacuum line and vent valve for cracks, splits and correct routing
- Test the switch for continuity in both positions with the connector unplugged
- Inspect the connector and harness in the pedal box for corrosion, chafing and moisture
- Replace or readjust the clutch vacuum vent valve switch
- Confirm on a road test that cruise control engages and cancels correctly with the clutch