Ignition Switch Accessory Position Circuit High Voltage
The P2538 code indicates that the Powertrain Control Module (PCM) has detected a voltage signal from the ignition switch accessory position circuit that is higher than the expected range. This circuit provides power to accessories like the radio and power windows when the key is in the accessory position. A high voltage reading can be caused by a faulty ignition switch, a short to voltage in the wiring, or a malfunctioning PCM. This issue may prevent accessories from working correctly or cause intermittent electrical problems.
1. Most Common Causes
- Faulty or worn ignition switch
- Short to battery voltage in the ACC position circuit wiring
- Corroded or loose connector/terminal at the ignition switch
- Internal failure of the body control module (BCM) or ECM/PCM
- Excessive resistance in the signal circuit ground
- Improperly installed aftermarket electrical modification
2. Symptoms You Will Notice
- Accessories (radio, windows) not working in accessory position
- Engine may not start or start intermittently
- Battery drain when key is off
- Check Engine Light illuminated
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for related codes.
Step 2: Inspect the ignition switch and its connector for damage, corrosion, or loose pins.
Step 3: Test the voltage at the accessory circuit with a multimeter; compare to manufacturer specs.
Step 4: Check for shorts to voltage in the wiring harness between the ignition switch and PCM.
Step 5: If wiring and switch are okay, test the PCM for proper operation (rare).
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause electrical issues, battery drain, or prevent the engine from starting. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and replacement of the ignition switch, but can be higher if wiring repairs are needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.