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P2535 OBD-II Trouble Code: Ignition Switch Run/Start Position Circuit High

Check Engine Light

P2535 code definition

When the P2535 code is stored, it means that the PCM has found an issue with the ignition switch run position circuit.

What the P2535 code means

The ignition switch is what delivers voltage to your vehicle’s fuel delivery and ignition systems, and to the PCM itself. The PCM expects that the input reference voltage will be approximately the same as the battery voltage, which is 12.6 volts. If the signal goes below the acceptable voltage, the P2535 code is stored.

What causes the P2535 code?

Most of the time, the cause of the P2535 code is a bad ignition switch. Other causes can include:

  • Burned out fuses
  • Burned fusible links
  • Corroded, shorted or open wiring
  • Damaged electrical connectors
  • Corroded battery cables
  • Bad alternator
  • Bad battery

What are the symptoms of the P2535 code?

The Check Engine light and/or the System Failure light may come on, or you vehicle may start hard or not at all.

How does a mechanic diagnose the P2535 code?

The ignition switch is what delivers voltage from your battery to the other systems in the vehicle. When you place your key in the ignition and turn it, a mechanical actuator slides an electronic into place so that your vehicle’s components get the voltage they need. Wiring and cables deliver battery voltage to the input side of the switch. When you turn the key off, battery voltage is conserved. In the “accessory” or “auxiliary” position, the voltage is delivered only to limited systems that are in use when your vehicle is not moving.

Your mechanic uses a number of tools and techniques to diagnose the P2535 code, including:

  • Using a code reader or scanner along with a digital volt/ohmmeter to diagnose the code
  • Using the vehicle manufacturer’s wiring diagram in order to inspect the ignition connectors and switch wiring

  • Replacing or repairing any damaged wiring, connectors and other components as needed

  • Re-testing the system after repairs are done, and if everything appears to be working properly, using the scanner again to record any codes and freeze frame data

  • Clearing the codes, and running your vehicle to see if the codes return

  • Checking battery voltage and ground signals

  • Using the ohmmeter to see if any battery voltage or ground circuits are open, and if there is resistance in both circuits (this is done with all control modules disconnected in order to prevent damage)

  • Checking fuses and fusible links

  • Testing related circuits and comparing the findings with manufacturer specs

  • Replacing or repairing any bad circuits, connectors or other components that are not coinciding with manufacturer’s specifications

  • Re-testing the system again

Common mistakes when diagnosing the P2535 code

A faulty battery is sometimes blamed for the P2535 code and the attendant symptoms, when the problem is actually with the ignition switch or the alternator.

How serious is the P2535 code?

The P2535 code is not something you need to deal with right away. Keep in mind, though, that if you do not have the source of the problem identified, your car may fail to start.

What repairs can fix the P2535 code?

Sometimes all that is needed is to have your battery cables cleaned up. Any damaged wiring, [connectors or other components](https://www.yourmechanic.com/services/connector-hose-heater-control-valve-replacement can be replaced, and if the problem is the battery itself, you can also have that replaced.

Additional comments for consideration regarding the P2535 code

Mechanic to provide

Need help with a P2535 code?

YourMechanic has fully qualified mechanics on staff who will be happy to come to your home or workplace and diagnose and repair your vehicle. Call us at 1-800-701-6230 to arrange an appointment at the location of your choice, or to get a free quote. You can also use our online form to book service.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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