Faulty cruise control switch or steering wheel control module with internal short or worn contacts; Signal wire chafed and shorted to earth in the steering column or wiring loom; Corroded, damaged or contaminated connector causing low voltage on the input circuit; Worn or damaged clock spring (spiral cable) in the steering wheel on models where the switches connect through it; Stuck or sticking button after spillage or wear, holding the circuit at a low value; Faulty control unit input or internal reference voltage fault.

P0592

Cruise Control Multi-Function Input B Circuit Low.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
92: FaultThe specific fault in that area

What it means

P0592 means the control unit has detected a low voltage signal in the cruise control multi-function input B circuit. This input is normally a switch or steering wheel control that carries several cruise functions (such as set, resume, cancel) on one signal wire. The code sets when the monitored voltage falls below the expected range, which suggests a short to earth, a high-resistance fault or a faulty switch. The exact circuit layout and which control unit monitors it vary by model.

Symptoms

Cruise control will not engage or set
Cruise control cancels itself unexpectedly
Cruise control buttons give no response or erratic response
Cruise control warning light or malfunction message on the dash
Engine management light may be on

Possible causes

Faulty cruise control switch or steering wheel control module with internal short or worn contactslikely
Signal wire chafed and shorted to earth in the steering column or wiring loomlikely
Corroded, damaged or contaminated connector causing low voltage on the input circuitpossible
Worn or damaged clock spring (spiral cable) in the steering wheel on models where the switches connect through itpossible
Stuck or sticking button after spillage or wear, holding the circuit at a low valuepossible
Faulty control unit input or internal reference voltage faultrare

How to diagnose

Read the stored codes and freeze frame data, note any other cruise, brake switch or steering control codes, then record and clear only after diagnosis
Check the cruise control switch operation and look for sticking buttons, damage or spilled liquid
Inspect the wiring and connectors at the switch, steering column and control unit for chafing, corrosion, water ingress or pin damage
Using the manufacturer wiring diagram, identify the input B circuit, reference voltage and earth for this model
With the ignition on, measure the signal voltage at the switch and check it changes correctly as each button is pressed
Test the signal wire for a short to earth and for unwanted resistance with the circuit disconnected at both ends
Check the clock spring or steering column connection continuity if the switches pass through it, following model-specific procedures
Confirm the control unit reference supply and earth are good before suspecting the unit itself

How to fix

Replace the faulty cruise control switch or steering wheel control assembly
Repair or replace the chafed or shorted wiring, using proper joints and securing the loom correctly
Clean, repair or replace corroded or damaged connectors and terminals
Replace the clock spring if testing shows it is faulty
Replace or reprogram the control unit only after all wiring and switch faults are ruled out, as the manufacturer specifies

Can I keep driving?

Low severity

The car is generally safe to drive as only the cruise control function is affected, though it will not work properly. Book it in for repair at your convenience, and have it checked sooner if other steering or brake switch warnings appear.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.