P0593
Cruise Control Multi-Function Input B Circuit High
Cruise control
Generic OBD-II
Low
What it means
P0593 means the PCM sees the cruise-control multi-function switch input "B" reading high (a short to voltage or a switch/wiring fault). This input carries your cruise button presses, so the practical effect is that cruise control won't set or respond. It's a low-severity signalling fault — the engine and brakes are unaffected.
Low
Can I keep driving? Safe to drive — only the cruise-control switch input is affected; the engine runs normally.
Common symptoms
What you'll notice
- Cruise control won't set or hold speed
- Cruise-control switches unresponsive
- Check-engine light on
Common causes
Most likely first
- Failed cruise-control multi-function switch BLikely
- Short to voltage on the switch input circuitCommon
- Corroded or damaged connector or wiringCommon
- PCM/cruise module fault (rare)Less often
How to diagnose & fix
Work through it in order
- Inspect the cruise multi-function switch connector and wiring for a short to voltage or corrosion.
- With a scan tool, watch the switch input while pressing each cruise button; a signal stuck high confirms the fault.
- Replace the cruise-control multi-function switch if it doesn't read correctly.
- Repair any wiring faults, then clear and re-test the cruise control.
FAQ
Quick answers
Is it safe to drive with P0593?+
Yes. This affects only the cruise-control switch input — braking, steering, and engine performance are all normal.
Can I just clear P0593?+
It returns until the switch or wiring is fixed. Clear it after the repair to confirm cruise control works again.
Related codes
Often seen with P0593
Read & clear P0593 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX