P0589 Code Definition
The P0589 code is a generic powertrain code related to the vehicle speed control and idle control system. In this case, the engine control module (ECM) has found a fault in the cruise control multi-function input “B” circuit.
Codes related to the P0589 include: * P0590: Cruise Control Multi-Function Input “B” Circuit Stuck * 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
What the P0589 Code Means
When a P0589 code is stored, the vehicle’s ECM has found a fault in the electrical circuit of the cruise control system. A vehicle’s ECM works with the cruise control module (on most vehicles) to automatically control the vehicle’s speed. Cruise control works to help a driver maintain a safe speed without the need to constantly keep pressure on the accelerator pedal.
In most modern vehicles, cruise control is achieved through the use of a small servo motor attached to the throttle linkage. The ECM and cruise control module sends a voltage signal, telling the servo motor to open the throttle to slow the vehicle, or close the throttle to increase the vehicle’s speed.
A vacuum operated cruise control system uses a combination of vacuum from the engine and the electronic cruise control module to operate. Engine vacuum is constantly supplied to the cruise control servo solenoid, and when the cruise control module sends the signal to set the cruise control, the servo solenoid opens for vacuum to get to the servo. Then, the cruise control module utilizes a signal from the cruise control switch operated by the driver to ensure the correct amount of vacuum to decrease, maintain, or increase engine speed as necessary.
This P0589 code can be caused by the variable valve or cylinder management system turning on and off during cruising speeds, light throttle conditions, or on flatter roads. This excessive switching can cause increased oil consumption, dropping oil pressure levels outside of allowed parameters and can no longer operate the valve or cylinder management system. If the ECM cannot control the vehicle’s speed, the system initiates a self test and stores the P0589 code if the voltage/resistance level in the cruise control system is not normal.
What Causes the P0589 Code?
Several problems may cause a P0589 code including: * Damaged, defective, or faulty cruise control switch * Damaged, open, or shorted circuitry in the cruise control button (possibly caused by spilled liquids) * Damaged or leaking vacuum supply hose * Blown fuse(s) * Damaged or corroded connectors
What are the Symptoms of the P0589 Code?
Symptoms of a P0589 code may include: * Warning or service light may illuminate * Cruise control may not engage * Cruise control may engage and disengage * There may be no obvious symptoms aside from a stored code
How Does a Mechanic Diagnose the P0589 Code?
A mechanic may use several methods to diagnose a P0589 trouble code, including: * Utilize an OBD-II scanner to check for a stored P0589 trouble code * Check for blown fuse(s) * Visually inspect wiring and connectors for signs of damage or corrosion * Visually inspect the vacuum supply hoses for damage * Perform a vacuum pressure test * Test the one-way vacuum valve (blow air through both ends to ensure air only goes through one direction) * Test the cruise control switch for voltage with a digital volt/ohmmeter * Test continuity in the cruise control circuitry
Common Mistakes when Diagnosing the P0589 Code
If a fuse is blown, be aware that it may be a symptom of a larger problem. Be sure to check for all stored diagnostic trouble codes (DTCs) and diagnose them in the order in which they appear.
How Serious is the P0589 Code?
Because a vehicle’s safe driving operation will most likely not be impacted due to faults that store a P0589 code, this code is not considered to be serious code. However, when this code appears, it is recommended to take your vehicle to your local service center or mechanic for repair and diagnosis as soon as possible.
What Repairs can Fix the P0589 Code?
Several repairs can fix a P0589 trouble code and include: * Repair or replace any damaged, corroded, or loose wiring or connectors * Replace any blown fuse(s) * Replace any damaged connectors * Replace any damaged vacuum supply hoses * Replace damaged or defective one-way vacuum valve * Replace a damaged or defective cruise control switch * Clear all codes, test-drive the vehicle, and rescan to see if any codes reappear
Additional Comments for Consideration Regarding the P0589 Code
Sometimes, a P0589 code can be caused simply from spilling liquids inside your vehicle. Keep your vehicle clean and in good operating condition, and avoid expensive repairs that can be avoided.
Need Help with a P0589 Code?
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