This code indicates that the powertrain control module (PCM) has detected a low voltage condition in the ignition switch accessory position circuit. It typically means the electrical signal that tells the computer the key is in the Accessory or Run position is missing, weak, or shorted to ground.
The internal electrical contacts inside the ignition switch can wear out, burn, or corrode over time, leading to a loss of voltage in the accessory circuit.
The wiring harness between the ignition switch and the PCM can become chafed, melted, or broken, causing the voltage signal to drop to zero.
The electrical connector at the ignition switch or the PCM can develop corrosion, spread pins, or lose contact, resulting in high resistance and a low voltage reading.
A blown fuse protecting the ignition or accessory circuit will cut power to the switch, resulting in a low or zero voltage signal at the PCM.
A rare internal failure within the control module's input circuit could cause it to misread the voltage. This is highly uncommon and should only be considered after all wiring and switches are verified.
It depends on the exact failure. If the vehicle starts but accessories like the radio or wipers are dead, it may be drivable in fair weather. However, if the circuit affects the fuel or ignition system, the car may stall or not start at all.
No, this code refers to the electrical ignition switch located behind the mechanical lock cylinder. The cylinder can turn perfectly fine while the electrical switch behind it is failing.
No, replacing the PCM is almost never the correct fix for P2537. Drivers and technicians are sometimes too quick to blame the computer, but this code is overwhelmingly caused by a worn ignition switch, damaged wiring, or a poor connection.
You risk being stranded if the vehicle refuses to start, or you may lose critical safety accessories like windshield wipers while driving. It is best to diagnose and repair the underlying electrical fault.