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P0592 — Cruise Control Multi Function Input B Circuit Low

Generic OBD-II · all makesPowertrain (engine & transmission)

OBD-II code P0592 indicates that the powertrain control module (PCM) has detected a low voltage condition in the 'B' input circuit of the cruise control multi-function switch. This typically means there is a short to ground, a faulty switch, or a wiring issue preventing the engine computer from reading the cruise control button inputs correctly.

Symptoms

What causes it — most likely first

1. Faulty cruise control switch

The multi-function switch on the steering wheel or stalk wears out internally or suffers liquid damage, causing a short to ground.

2. Wiring short to ground

The wiring between the cruise control switch and the PCM is chafed or damaged, causing the circuit voltage to drop below the expected threshold.

3. Faulty clock spring

The clock spring assembly in the steering column fails electrically, interrupting or shorting the signal path from the steering wheel buttons to the vehicle harness.

4. Corroded or loose connector

A poor electrical connection at the switch, clock spring, or PCM causes high resistance or an open circuit that mimics a low voltage condition.

5. Failed PCM or ECM

The engine computer has an internal fault on the specific input circuit. This is highly uncommon and should only be considered after all wiring and switches are verified.

How it's diagnosed

  1. Use a diagnostic scanner to read all stored codes and clear them to see if P0592 returns after a test drive.
  2. Perform a visual inspection of the cruise control switches, steering column wiring, and related connectors for signs of damage, corrosion, or liquid spills.
  3. Monitor the cruise control switch 'B' input data stream using a scan tool while pressing the buttons to see if the PCM registers the changes.
  4. Use a digital multimeter to test the resistance and continuity of the switch itself, comparing results to factory specifications.
  5. Trace the wiring from the switch through the clock spring to the PCM, checking for continuity and shorts to ground.
  6. If all switches, wiring, and clock spring tests are normal, verify PCM power and grounds before considering control module failure.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make

Frequently asked

Can I still drive my car with a P0592 code?

Yes, the vehicle is safe to drive, but the cruise control system will likely be disabled until the issue is resolved.

Will a P0592 code cause my vehicle to fail an emissions test?

In most regions, a cruise control code will not cause an emissions failure, but the illuminated Check Engine Light may automatically fail an OBD-II readiness check depending on local laws.

Do I need to replace the PCM to fix a P0592 code?

No, replacing the PCM is rarely the correct fix for this code. Drivers are sometimes told the computer is bad, but the actual cause is almost always a worn-out cruise control switch, a damaged wire in the steering column, or a faulty clock spring.