Cruise control buttons are almost always a resistor ladder on one or two signal lines, each button giving its own voltage; the module reading it (GM and Saab from about 2010: the body module; FCA: steering column module or PCM) sends the button state to the engine module over CAN. CARB names cruise control as the example of an emission-neutral diagnosis – it is simply switched off – so GM lists all these codes as type C and Ford as non-MIL: no warning lamp, the engine runs normally. P0577 means the input signal is above its upper limit – an open signal or switch ground (often in the clockspring) or a short to positive. FCA's ladder treats over 4.706 V as circuit high, with about 4.54 V at rest. No manufacturer document available to us uses this code. For line A makers use P0581.
Low severity. Can I keep driving?You can keep driving, but check that the brake lights work: that part is a safety issue.
Symptoms
- Cruise control inoperative
- Cruise control locked out
- No check engine light, engine runs normally
Most likely causes
- Signal or switch ground open (clockspring)
- Signal shorted to positive
- Module faulty
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
What each character of P0577 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 5: Speed and idle
- 77: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0577?
You can keep driving, but check that the brake lights work: that part is a safety issue.
What causes code P0577?
The most common causes are: signal or switch ground open (clockspring); signal shorted to positive; module faulty.
Related codes
- P0575Cruise Control Input Circuit
- P0576Cruise Control Input Circuit Low
- P0581Cruise Control Multi-Function Input A Circuit High
- P0564Cruise Control Multi-Function Input A Circuit
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.