The code indicates the Powertrain Control Module (PCM) has detected voltage on the cruise-control servo control circuit that exceeds the calibrated threshold. This typically means the circuit is shorted to voltage, the servo actuator has an internal electrical fault, or there is a high-resistance connection causing an abnormal voltage reading. The PCM disables cruise control when this fault is present to prevent unintended throttle operation.
The wire between the PCM and cruise servo is chafed, melted, or damaged, allowing it to contact a voltage source such as the battery feed or another powered circuit.
Internal short to voltage or open circuit within the servo motor assembly causes the control circuit to read high voltage regardless of PCM command.
Moisture, oxidation, or bent terminals at the servo or PCM connector create high resistance or unintended voltage paths that raise circuit voltage.
Poorly integrated remote starters, alarms, or audio components tapped into the cruise circuit can bleed voltage onto the control wire.
Rare internal driver circuit fault within the PCM that incorrectly outputs or monitors high voltage; only consider after verifying wiring and servo integrity.
Yes. The fault affects only the cruise control system, so normal throttle operation, braking, and driving safety are unaffected.
No. The PCM is rarely the cause of P0596. Most instances are resolved by repairing wiring shorts or replacing the servo actuator.
Intermittent connection or wire movement can temporarily complete or break the circuit, causing sporadic operation until the fault becomes permanent or the wire position changes.
It is usually mounted on the driver-side strut tower, firewall, or adjacent to the throttle body, depending on whether the vehicle uses a cable-driven or electronic throttle actuator.