Cruise Control Input Circuit High
P0577 indicates the ECM detected a high voltage condition in the cruise control input circuit. This causes the cruise control system to malfunction or disable as a safety measure, but does not affect engine operation or immediate driveability.
What You Might Notice
- Cruise control system does not engage or function
- Check engine light (CEL) illuminated
- Cruise control buttons unresponsive
- Loss of all cruise control features
- Normal vehicle operation otherwise unaffected
Most Common Causes
- 1
Defective cruise control switch
The cruise control input switch may have failed or developed an internal short circuit causing high voltage to be sent to the ECM.
- 2
Wiring short to power
The cruise control circuit wiring may be shorted to power, causing excessive voltage on the control signal line.
- 3
Damaged cruise control stalk connector
Corrosion or loose connections on the cruise control stalk connector can cause intermittent high voltage signals.
- 4
ECM or module communication fault
A faulty ECM input circuit or related control module may incorrectly sense normal voltage as high voltage.
How to Diagnose It
- 1
Check Defective cruise control switch — The cruise control input switch may have failed or developed an internal short circuit causing high voltage to be sent to the ECM.
- 2
Check Wiring short to power — The cruise control circuit wiring may be shorted to power, causing excessive voltage on the control signal line.
- 3
Check Damaged cruise control stalk connector — Corrosion or loose connections on the cruise control stalk connector can cause intermittent high voltage signals.
- 4
Check ECM or module communication fault — A faulty ECM input circuit or related control module may incorrectly sense normal voltage as high voltage.
How to Fix It
- 1
Test and replace cruise control switch
Use a multimeter to test the cruise control switch for proper voltage levels. If voltage is excessive or the switch does not respond to button inputs, replace the cruise control stalk assembly.
- 2
Inspect cruise control wiring for shorts
Trace the cruise control circuit wiring harness for damage, pinched wires, or exposed insulation that could be shorting to battery voltage. Repair or replace damaged wiring sections.
- 3
Check and clean cruise control connector
Disconnect the cruise control switch connector and inspect for corrosion, loose pins, or water intrusion. Clean with electrical contact cleaner and reconnect firmly.
- 4
Clear code and retest system
After repairs, use a diagnostic scanner to clear the P0577 code. Test cruise control operation through multiple driving cycles to confirm the fault is resolved.
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