P2536 means the powertrain or body control module has detected an abnormal voltage, resistance, or state in the ignition switch accessory (ACC) position circuit. This circuit signals when the key is in the accessory position, and the code sets when the module sees a value outside its expected range.
Internal electrical failure or contact wear inside the ignition switch prevents the accessory position circuit from producing the correct signal voltage or resistance.
The wire running between the ignition switch and the monitoring module may be broken, chafed, or shorted to ground or another circuit.
Poor pin contact or corrosion at the ignition switch pigtail or control module connector introduces excessive resistance or intermittent signal loss.
Non-factory devices improperly tapped into the accessory circuit can alter circuit voltage or resistance and trigger a rationality fault.
In rare cases the PCM or BCM may misinterpret a valid signal due to an internal input failure; this should only be considered after the switch and wiring are proven good.
Generally yes, but accessories may behave erratically or fail to operate, and the warning light will stay on until the underlying circuit fault is corrected.
Not without testing. While a failed ignition switch is the most common cause, wiring and connector faults are also frequent; confirm root cause before replacing parts.
Usually no. Control module failure is an uncommon cause of P2536. Most instances are traced to the ignition switch assembly or its wiring. A module should only be replaced after the circuit and switch have been thoroughly tested and ruled out.
Yes. If an aftermarket device has been connected to the accessory circuit improperly, it can alter the circuit’s voltage or resistance and cause the module to set P2536.