Faulty ignition switch internal contacts for the accessory position, causing high resistance or an open circuit; Damaged or corroded wiring harness between the ignition switch and the body control module or fuse box; Blown fuse or poor connection in the accessory circuit fuse holder; Loose or corroded ground connection for the ignition switch or accessory circuit; Failed body control module (BCM) or powertrain control module (PCM) internal driver for the accessory sense circuit; Aftermarket accessories improperly tapped into the accessory circuit, causing a short or excessive load; Ignition switch actuator rod or linkage misalignment preventing proper contact in the accessory position

DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2537

P2537Ignition Switch Accessory Position Circuit Low

Q: What does code P2537 mean?

Ignition Switch Accessory Position Circuit Low. P2537 indicates that the ignition switch accessory position circuit is reporting a low voltage condition, meaning the body control module or powertrain control module sees the accessory feed at or near ground when it should be at battery voltage. This typically occurs when the key is turned to the accessory position or when the circuit is expected to be live, and the module detects an abnormally low signal on the accessory sense wire.

P2537 indicates that the ignition switch accessory position circuit is reporting a low voltage condition, meaning the body control module or powertrain control module sees the accessory feed at or near ground when it should be at battery voltage. This typically occurs when the key is turned to the accessory position or when the circuit is expected to be live, and the module detects an abnormally low signal on the accessory sense wire.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Often no symptoms besides the warning light, especially if the accessory circuit still powers some components intermittently
Accessory-powered devices such as the radio, power windows, or cigarette lighter may not work when the key is in the accessory position
The engine may crank but not start if the module misinterprets the accessory signal as a security or ignition state issue
Intermittent operation of accessories when the key is wiggled or the steering column is adjusted
A no-start condition where the starter does not engage because the module does not recognize the key position
Other unrelated warning lights or communication codes may appear if the low signal affects module wake-up

Common causes, most likely first

Faulty ignition switch internal contacts for the accessory position, causing high resistance or an open circuit
Damaged or corroded wiring harness between the ignition switch and the body control module or fuse box
Blown fuse or poor connection in the accessory circuit fuse holder
Loose or corroded ground connection for the ignition switch or accessory circuit
Failed body control module (BCM) or powertrain control module (PCM) internal driver for the accessory sense circuit
Aftermarket accessories improperly tapped into the accessory circuit, causing a short or excessive load
Ignition switch actuator rod or linkage misalignment preventing proper contact in the accessory position

How to diagnose and fix it

Verify the code with a scan tool and check for any related communication or ignition switch codes before proceeding
Inspect the accessory circuit fuse and replace it if blown, then recheck for the code
Perform a voltage drop test on the accessory circuit wiring from the ignition switch to the module, looking for excessive resistance
Check the ignition switch connector for corrosion, loose pins, or melted plastic, and repair or replace the connector as needed
Test the ignition switch with a multimeter in the accessory position to confirm continuity and correct voltage output
If the switch and wiring test good, check the ground circuit for the ignition switch and module, cleaning and tightening as necessary
Substitute a known-good ignition switch or module only after all wiring and voltage tests pass, then clear codes and verify the repair

Accessory circuit faults that mimic switch failure

A common misdiagnosis is replacing the ignition switch when the real fault is a corroded ground or a chafed wire behind the dash that only shows up when the steering column is tilted.
Aftermarket alarms, remote starters, or phone chargers spliced into the accessory wire can backfeed voltage or create a short that sets P2537 without any factory component being defective.
Some vehicles set P2537 when the battery is weak or during jump-starting because the module sees a momentary low voltage on the accessory sense line, so always clear the code and retest before condemning parts.
The accessory position circuit often shares a fuse or relay with other low-current circuits, so a fault in a seemingly unrelated component can pull the accessory signal low and trigger this code.
On vehicles with push-button start, the accessory position is controlled by the BCM and a failing brake pedal switch or key fob battery can create conditions that set this code even though the ignition switch itself is fine.

Can I keep driving with P2537?

You can usually drive the vehicle if it starts and runs normally, but avoid using accessory-powered devices and do not rely on the accessory position for safety-related functions. If the engine cranks but does not start or the warning light is accompanied by stalling, have the vehicle towed to a shop rather than continuing to drive.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.