OBD-II code P2535 indicates that the Powertrain Control Module (PCM) has detected a high voltage signal on the ignition switch 'on/start' circuit when it should be low. This typically means the circuit is shorted to power, the ignition switch is stuck or faulty, or there is a wiring issue causing an unexpected voltage reading.
Internal wear or damage can cause the switch to send a continuous high signal, even when the key is not in the start position.
Wires chafed against metal or melted together can create a short to power, keeping the circuit voltage high.
Corrosion, bent pins, or a loose connector can cause poor contact or bridging, leading to a false high signal.
A relay that is stuck closed can back-feed voltage into the ignition switch circuit, mimicking a high signal.
Improperly installed or failing aftermarket electronics can interfere with the ignition circuit and cause this code.
An internal short in the PCM is possible but highly unlikely; this should only be considered after all other causes are ruled out.
It means the PCM has detected a high voltage on the ignition switch 'on/start' circuit when it expected a low voltage. This often points to a short to power, a stuck ignition switch, or a wiring fault.
It depends on the symptoms. If the engine starts and runs normally, you may be able to drive, but the issue could worsen and lead to a no-start condition or electrical damage. It's best to diagnose and repair it promptly.
No. PCM failure is very rare for this code. The most common causes are a faulty ignition switch, damaged wiring, or a shorted starter relay. The PCM should only be suspected after all other possibilities are thoroughly ruled out.
Start by inspecting the ignition switch and its wiring. If the switch is worn or shorted, replace it. Repair any damaged wiring or connectors. If an aftermarket alarm or remote start is installed, check its connections. Only replace the PCM if all else fails and testing confirms it is defective.