P0593 code meaning
Cruise Control Multi-Function Input B Circuit High
What P0593 means
Cruise control buttons form a resistor ladder on one or two signal lines, each button giving its own voltage window. FCA uses two lines with offset windows – signal 1 is input A, signal 2 input B – and both must report the same button; GM evaluates the ratio to the reference. Any fault locks out cruise control; CARB treats this as emission-neutral, and GM and Ford set these codes without warning lamp. P0593 means signal line B is too high: GM at a ratio of 1.005–1.035 for over 2 s (short to power), FCA above 4.706 V with about 4.54 V at rest. In FCA's Jeep Wrangler JK recalls it is a typical sign of a dusty clockspring.
P0593 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0593
- Cruise control inoperative, possibly airbag warning (Jeep JK)
- Cruise control locked out
- No check engine light
Common causes of P0593
- Most likelyClockspring dirty or faulty
- PossibleLine B shorted to positive or ground open
- PossibleButton block or connector
- Less likelyModule
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cruise control switchClockspringSwitch wiringBody control module
What each part of P0593 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 93 | The exact fault in that area. |
What to do next
- Note P0593 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0593
What does P0593 mean?
P0593 means "Cruise Control Multi-Function Input B Circuit High". Cruise control buttons form a resistor ladder on one or two signal lines, each button giving its own voltage window. It is a generic code, so it means the same on every make.
Is it safe to drive with P0593?
P0593 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0593 fail an emissions test?
P0593 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0593 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P0593 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.