29-12-2024
13 min.
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P0589 Cruise Control Multi-Function Input "B" Circuit

P0589 is an OBD-II diagnostic trouble code indicating a problem with the Cruise Control Multi-Function Input "B" circuit.

In simple terms, the vehicle's control module has detected an electrical problem involving one of the input circuits used to receive commands from the cruise-control multifunction switch.

This circuit can be associated with buttons such as ON/OFF, SET, RESUME, CANCEL, ACCEL or COAST, depending on the vehicle's design.

Unlike P0591, which specifically indicates a Range/Performance problem, P0589 identifies a more general malfunction in the designated Cruise Control Multi-Function Input "B" circuit.

What Does P0589 Mean?

The code can be understood as follows:

P – Powertrain-related diagnostic trouble code
05 – Cruise-control and related speed-control functions
89 – Specific fault identifier
Cruise Control Multi-Function Input "B" – A manufacturer-defined input circuit associated with the cruise-control multifunction controls
Circuit – The electrical pathway used to transmit the switch command to the appropriate control module

The important point is that P0589 does not automatically mean the cruise-control switch is defective.

The fault can be anywhere in the electrical path between the switch and the module that interprets the input.

What Is the Cruise Control Multi-Function Input "B" Circuit?

Modern cruise-control systems can use several switches to control vehicle speed.

Depending on the vehicle, the driver may have buttons for:

Cruise control ON/OFF
SET
SET-
RESUME
RES+
CANCEL
COAST
ACCEL
Speed limiter functions

These buttons must communicate their commands to a control module.

Some vehicles use separate wires for individual switches. Others use a shared input circuit in which different buttons create different electrical resistance or voltage values.

For example, several buttons might be connected to a common input wire. Each button can produce a different resistance, allowing the control module to determine which button has been pressed.

Therefore, a problem with one wire, resistor, connector or switch can affect the interpretation of multiple commands.

What Does the "B" Mean?

The "B" designation is not a universal physical wire designation.

It is used by the vehicle manufacturer to distinguish one cruise-control input circuit from another.

This means that you should not assume that "Input B" always refers to a particular pin, wire color or connector.

The exact circuit must be identified using the manufacturer's wiring diagram and service information for the specific vehicle.

What Is the Difference Between P0589 and P0591?

These two codes are closely related but are not identical.

P0589 – Cruise Control Multi-Function Input "B" Circuit

This indicates a general electrical malfunction involving the designated input circuit.

P0591 – Cruise Control Multi-Function Input "B" Circuit Range/Performance

This indicates that the module is receiving a signal but considers the signal's range or behavior incorrect.

Other related codes can further identify the electrical condition.

For example:

P0592 – Input "B" Circuit Low
P0593 – Input "B" Circuit High

So P0589 is more general, while P0591, P0592 and P0593 provide more specific information about the signal behavior.

Common Causes of P0589

Several faults can cause P0589.

1. Faulty cruise-control multifunction switch

The cruise-control switch may have worn or damaged internal contacts.

A switch can sometimes work intermittently before failing completely.

2. Damaged wiring

A broken, partially broken or shorted wire can prevent the switch signal from reaching the control module correctly.

Wiring around the steering wheel and steering column deserves particular attention.

3. Faulty clock spring

If the cruise-control controls are mounted on the steering wheel, their electrical signals generally have to pass through a clock spring.

A damaged clock spring can interrupt the connection between the rotating steering wheel and stationary wiring.

4. Loose connector

A poorly seated connector can cause intermittent electrical contact.

5. Corroded connector terminals

Corrosion can increase resistance or interrupt the signal.

Even a small amount of corrosion can cause problems in a low-current switch circuit.

6. Short to ground

A signal wire may be unintentionally connected to ground.

The result depends on the specific circuit design.

7. Short to voltage

A signal wire can also contact a voltage source.

This can cause the module to see an abnormal input.

8. Open circuit

A wire, terminal or switch contact may be completely disconnected.

An open circuit can prevent the module from receiving the expected input.

9. Damaged resistor network

Some multifunction cruise-control systems use resistor values to distinguish between buttons.

A damaged resistor can therefore cause the module to misinterpret the button command.

10. Reference-voltage problem

Some systems use a reference voltage for the multifunction switch circuit.

If the reference voltage is incorrect, the switch signals may also be interpreted incorrectly.

11. Ground problem

A poor ground can produce abnormal electrical readings and may cause several electronic faults at the same time.

12. Body control module or communication problem

On some vehicles, the steering-wheel buttons communicate with a body-control module or another electronic module rather than directly with the engine ECU.

A problem with that module or its communication network can therefore cause cruise-control input faults.

13. Control module fault

An ECM, PCM, BCM or another control unit can theoretically cause the problem.

However, module replacement should be one of the last steps, not the first.

Symptoms of P0589

The symptoms depend on the vehicle and the exact circuit fault.

Common symptoms include:

Cruise control does not operate
Cruise control cannot be switched on
SET button does not work
RESUME button does not work
CANCEL button does not work
Cruise-control speed cannot be adjusted
Cruise control operates intermittently
Cruise-control warning or indicator appears
Check Engine Light comes on
Some steering-wheel controls stop functioning

In some vehicles, there may be no noticeable engine-performance problem.

The engine can run normally because the fault concerns the input circuit used by the cruise-control system.

Can P0589 Disable Cruise Control?

Yes.

If the control module cannot reliably determine the driver's cruise-control commands, it may disable the cruise-control system.

This is a safety-related strategy.

For example, if the module cannot correctly determine whether the driver is requesting SET, RESUME or CANCEL, continuing to operate cruise control could be unsafe.

The system may therefore remain disabled until the electrical problem is corrected.

Can P0589 Affect the Engine?

Normally, P0589 does not directly cause an engine mechanical problem.

You generally should not expect it to cause:

Engine overheating
Low oil pressure
Mechanical engine damage
Misfires
Fuel-system problems

However, modern vehicles can react to electronic faults by changing how certain systems operate.

The most obvious effect of P0589 is usually cruise-control malfunction rather than a fundamental engine problem.

Is P0589 Serious?

P0589 is generally considered a moderate electrical fault rather than an immediate engine-damage problem.

If the vehicle drives normally and only the cruise-control system is affected, it is usually possible to drive the vehicle.

However, the fault should not simply be ignored.

An electrical problem in the steering-wheel controls can sometimes be accompanied by other faults, especially when the clock spring or steering-column wiring is involved.

Can You Drive With P0589?

In many cases, yes.

If:

The engine operates normally
Brakes work normally
Steering-wheel controls are otherwise normal
There are no major warning lights
Cruise control simply does not function

the vehicle can generally be driven without using cruise control.

However, if P0589 appears together with an airbag warning light, horn failure, multiple steering-wheel control failures or other electrical warnings, the vehicle should be inspected more promptly.

How to Diagnose P0589

A systematic electrical diagnosis is much more effective than immediately replacing parts.

1. Scan the vehicle for all fault codes

Do not look at P0589 in isolation.

Check every relevant control module for:

Stored codes
Pending codes
History codes
Communication faults
Steering-wheel-related faults
Brake-switch faults
Voltage-related faults

Additional codes can reveal whether P0589 is an isolated problem or part of a larger electrical failure.

2. Test all cruise-control buttons

Check every available function.

For example:

ON/OFF
SET
RESUME
CANCEL
ACCEL
COAST
Speed adjustment

If only one button does not work, the switch assembly becomes more suspicious.

If all buttons stop working simultaneously, look farther upstream.

3. Check other steering-wheel controls

Test the:

Horn
Audio buttons
Telephone controls
Menu buttons
Other steering-wheel switches

If several functions fail simultaneously, inspect the clock spring and common wiring.

4. Inspect the clock spring

If the vehicle uses steering-wheel-mounted controls, inspect the clock spring according to the manufacturer's procedure.

A clock spring is especially suspicious when several steering-wheel functions fail at the same time.

5. Inspect connectors

Look carefully for:

Corrosion
Bent terminals
Loose terminals
Broken locking tabs
Water contamination
Pulled-out wires
Damaged pins

A connector problem can produce exactly the same symptoms as a failed switch.

6. Inspect the wiring

Follow the circuit according to the wiring diagram.

Pay particular attention to areas around:

Steering column
Steering wheel
Clock spring
Steering-column connectors
Dashboard harness
Control-module connectors

A wire can be internally broken even if its insulation looks perfect.

Testing the Cruise-Control Switch

If the system uses a resistor-based switch network, the switch can often be tested by measuring resistance between the appropriate terminals.

Different buttons may produce different resistance values.

For example, conceptually:

No button → reference condition
SET → resistance value A
RESUME → resistance value B
CANCEL → resistance value C

The actual values can be completely different from one vehicle to another.

Therefore, never use generic resistance values as a substitute for the manufacturer's specifications.

Testing the Voltage Signal

On systems that use voltage-based input interpretation, a multimeter can be used to determine whether the input signal is behaving correctly.

The diagnostic process may involve checking:

Reference voltage
Signal voltage
Ground
Continuity
Resistance
Voltage drop

The technician should compare the measurements with the vehicle manufacturer's specifications.

The objective is to determine whether the abnormal signal originates from the switch, wiring, clock spring or control module.

Why the Clock Spring Is Important

The clock spring is one of the most important components to consider when diagnosing steering-wheel cruise-control problems.

The steering wheel rotates, while the wiring behind the steering wheel is stationary.

The clock spring allows electrical circuits to remain connected while the steering wheel turns.

Because it repeatedly winds and unwinds, it can eventually develop an internal electrical fault.

Depending on the vehicle, a failed clock spring can affect:

Cruise-control buttons
Horn
Steering-wheel controls
Airbag circuits

If P0589 appears together with several of these symptoms, the clock spring deserves close attention.

P0589 and Airbag Warning Lights

An airbag warning light should not automatically be attributed to P0589.

The cruise-control circuit and airbag circuits are separate systems, although they may physically share the steering-wheel/clock-spring assembly.

If both problems occur together, the clock spring or steering-wheel wiring may be a common physical area to investigate.

However, the airbag system should be diagnosed using the appropriate safety procedures.

P0589 and Brake Switch Problems

Cruise control also depends on brake-pedal information.

A faulty brake switch can disable cruise control.

However, a brake-switch problem does not automatically mean that P0589 was caused by the brake switch.

If a brake-switch code such as P0571 is also stored, the brake input should be diagnosed separately.

This distinction is important because cruise control involves several interconnected safety inputs.

P0589 and Aftermarket Modifications

Aftermarket electrical modifications can sometimes cause cruise-control input problems.

Potential examples include:

Aftermarket steering wheels
Cruise-control retrofits
Alarm systems
Remote-start systems
Multimedia installations
Steering-wheel control adapters
Non-original switch assemblies

If P0589 appeared immediately after electrical work, inspect the modified wiring first.

P0589 vs P0590

These codes are closely related.

P0589 refers specifically to a malfunction in the Cruise Control Multi-Function Input "B" circuit.

P0590 is generally associated with a malfunction involving the Cruise Control Multi-Function Input "B" circuit, depending on the exact SAE/manufacturer implementation.

Because manufacturers can implement the circuit differently, the diagnostic description displayed by the scan tool and the manufacturer's service documentation should be used to distinguish the exact fault.

P0589 vs P0591

This distinction is more straightforward.

P0589 – Cruise Control Multi-Function Input "B" Circuit

A general malfunction is detected in the input circuit.

P0591 – Cruise Control Multi-Function Input "B" Circuit Range/Performance

The module detects that the input signal is not behaving within the expected range or performance characteristics.

In other words, P0591 places greater emphasis on signal plausibility, while P0589 identifies a problem with the designated circuit more generally.

P0589 vs P0592 and P0593

These codes can provide more information about the electrical condition.

P0592 – Cruise Control Multi-Function Input "B" Circuit Low

The input signal is detected at an excessively low level.

P0593 – Cruise Control Multi-Function Input "B" Circuit High

The input signal is detected at an excessively high level.

P0589 – Cruise Control Multi-Function Input "B" Circuit

A general malfunction is detected without necessarily specifying a low or high condition.

If multiple codes are stored, the combination can help narrow down the problem.

Related Cruise-Control Codes

Other cruise-control DTCs that may appear during diagnosis include:

P0564 – Cruise Control Multi-Function Input "A" Circuit
P0565 – Cruise Control On Signal
P0566 – Cruise Control Off Signal
P0567 – Cruise Control Resume Signal
P0568 – Cruise Control Set Signal
P0569 – Cruise Control Coast Signal
P0570 – Cruise Control Accel Signal
P0571 – Brake Switch "A" Circuit
P0589 – Cruise Control Multi-Function Input "B" Circuit
P0590 – Cruise Control Multi-Function Input "B" Circuit
P0591 – Cruise Control Multi-Function Input "B" Circuit Range/Performance
P0592 – Cruise Control Multi-Function Input "B" Circuit Low
P0593 – Cruise Control Multi-Function Input "B" Circuit High

When several codes appear together, it is often more useful to look for a common electrical cause rather than replacing several components individually.

Common Diagnostic Mistakes

One of the most common mistakes is immediately replacing the cruise-control switch.

The switch may indeed be faulty, but the same symptoms can be produced by wiring, connectors or the clock spring.

Another mistake is replacing the ECU without proving that the ECU itself is defective.

A control module can correctly report P0589 because it is receiving an incorrect signal from somewhere else.

Other common mistakes include:

Ignoring the clock spring
Not checking the horn or other steering-wheel controls
Not checking connector terminals
Ignoring corrosion
Not checking grounds
Not checking reference voltage
Using generic resistance values
Clearing the code without performing electrical tests
Replacing multiple parts through trial and error
Ignoring other stored DTCs

How Do You Fix P0589?

The repair depends entirely on the cause.

Possible repairs include:

Replacing a faulty cruise-control switch
Repairing damaged wiring
Repairing or replacing a connector
Cleaning or repairing corroded terminals
Repairing a ground connection
Repairing a reference-voltage problem
Replacing a faulty clock spring
Correcting an aftermarket wiring installation
Repairing a body-control module or communication problem
Reprogramming or replacing a control module when properly diagnosed

The correct repair should be based on electrical testing rather than the code alone.

Can You Clear P0589?

Yes, a suitable OBD-II diagnostic scanner can normally clear the stored code.

However, clearing the code does not repair the circuit.

If the underlying problem remains, the control module will detect it again and P0589 may return.

After completing the repair, the proper procedure is generally:

Clear the stored DTC.
Verify the cruise-control input data.
Test all relevant buttons.
Check for additional warning lights.
Road-test the vehicle when safe.
Rescan the vehicle.
Confirm that P0589 does not return.

Final Thoughts on P0589

P0589 – Cruise Control Multi-Function Input "B" Circuit indicates a malfunction involving the electrical input circuit used by the cruise-control multifunction controls.

The cruise-control switch is only one possible cause. Wiring, connectors, the clock spring, reference voltage, ground connections, resistor networks and control modules can all be involved.

If the vehicle drives normally, P0589 is usually not an immediate engine-damage concern. The most obvious consequence is that cruise control may stop working or operate incorrectly.

The best diagnostic strategy is therefore to follow the electrical circuit from the multifunction switch through the clock spring and wiring to the control module, checking the actual signal rather than replacing components based solely on the DTC.