Why wont my car go out of accessory mode?
In most cars, accessory mode is a low-power state that leaves essential systems on while the engine stays off. To exit, you normally switch the ignition to the Run/On position or press the Start/Stop button with the brake applied. If your vehicle won't leave accessory mode, the likely culprits are a weak battery, a faulty ignition or start switch, or a safety interlock such as the brake switch or gear selector.
Understanding how your car exits accessory mode depends on whether you have a traditional key ignition or a push-button start. With a traditional key, you turn the key from ACC to ON (and sometimes to START) while applying the brake or clutch as required. With a push-button system, you typically press the brake and then press the Start/Stop button to move from ACC to RUN. If the car remains in ACC, a disturbance in the electrical system, a worn ignition component, or a failing interlock can prevent progression and may require targeted troubleshooting or professional inspection.
What Accessory Mode Is
Accessory mode is designed to power only certain electrical systems—such as the radio, lights, and dashboard displays—without starting the engine or draining the battery aggressively. This mode is common when you want to use electronics briefly, but it can become a mismatch if the vehicle expects a higher power state to proceed to Run/On. The exact path out of ACC varies by vehicle type, year, and whether your car uses a traditional ignition key or a modern push-button system.
Common Causes for Getting Stuck in Accessory Mode
The following are typical reasons a car might stay in accessory mode and what they usually point to:
- Weak or dead 12-volt battery. If the battery cannot hold enough voltage, the vehicle may stay in ACC or fail to advance to RUN.
- Faulty ignition switch or Start/Stop button. Wear or internal damage can prevent switching out of ACC even when you perform the usual actions.
- Brake pedal switch or clutch switch problem. Most cars require the brake (or clutch) to be engaged to move from ACC to RUN; a faulty switch can block progression.
- Gear selector interlock or not being in Park. Automatics often require Park (P) to exit ACC; a misaligned shifter or faulty interlock can keep you stuck.
- Steering column lock or related issues. If the steering lock engages unexpectedly or the column switch is faulty, ignition progression may be inhibited.
- Blown fuses or defective relays for ignition/ accessory circuits. A blown fuse can cut power to the circuits needed to leave ACC.
- Key recognition problems (for keyless systems). A failing key fob or weak battery in the fob can prevent the car from recognizing the key, leaving you in ACC.
- Electrical or control-module (BCM/ECU) faults. A fault in the vehicle’s control modules can misreport the state and block exit from ACC.
These issues range from simple battery or fuse problems to more involved failures in ignition hardware or safety interlocks. In some cases, an intermittent fault may not be easy to diagnose without codes read from the vehicle’s computer.
Troubleshooting Steps to Exit Accessory Mode
If you’re trying to get out of accessory mode, use these steps in order to isolate and address common problems. Each step addresses a likely cause and helps you decide whether you can fix it yourself or should seek professional help.
- Check the battery voltage. If you have a multimeter, measure the 12-volt battery; readings around 12.6 volts when resting are healthy. Below about 12.0 volts, voltage may be too low to reliably advance the ignition states. If the battery is weak, try charging or jump-starting from a known-good vehicle.
- Ensure the vehicle is in the correct position. For automatic transmissions, move the shifter fully into Park (P) and confirm the parking brake is engaged if applicable. For manual transmissions, ensure the clutch is fully depressed if required by your model.
- Test the brake/clutch interlock. Press the brake pedal firmly (or the clutch pedal on a manual) and hold while attempting to move to RUN or press the Start/Stop button. A faulty brake/clutch switch can prevent exiting ACC even when you think you’re pushing the brake.
- Inspect the ignition switch or Start/Stop system. If you’re using a traditional key, try rotating the key slowly from ACC toward ON and then to START. If it’s a push-button system, press the brake and hold the Start/Stop button for a moment longer, then release and press again if needed. If it fails consistently, a switch issue may be present.
- Check fuses and relays related to ignition and accessory circuits. A blown fuse can cut power to circuits essential for exiting ACC. If you find a blown fuse, replace it with the correct rating and re-test.
- Inspect the steering column and lock mechanism. Lightly wiggle the steering wheel while turning the ignition or Start button; a binding column lock can impede progression and require professional service if it’s contributing to the problem.
- Evaluate key recognition (for keyless systems). If you use a key fob, replace its battery and re-sync it if your vehicle supports re-synchronization. If the car doesn’t recognize the key, it may stay in ACC or refuse to enter RUN.
- Check for codes or warning messages. If the system detects a fault, a warning light or message may indicate what component is failing. A diagnostic scan can reveal a BCM/ECU or sensor problem needing professional attention.
If you still can’t exit accessory mode after these steps, the issue may be deeper than a simple user fix. Avoid repeated forced cycling, which can drain the battery further or mask an underlying fault. Contact roadside assistance or your dealership for a diagnostic and, if necessary, a repair appointment.
Summary
Accessory mode keeps essential electronics powered without starting the engine. If your car won’t exit this state, the most common causes are battery health, ignition or Start/Stop switch problems, safety interlocks such as brake or gear interlocks, or steering/lock issues. A structured check—battery voltage, gear position, interlocks, fuses, and key recognition—often identifies the culprit. If the problem persists, professional diagnosis is advised to prevent further electrical or safety-related complications.
