Code
P2535
Generic
P — Powertrain
Ignition Switch On/Start Position Circuit High
Views:
UK: 23
EN: 57
RU: 27
AI status
Completed
Completed
100%
Causes
- Open, damaged, or shorted wiring in the ignition switch ON/START circuit (short to battery voltage)
- Faulty ignition switch or worn contacts
- Poor or corroded connector or pin (ignition switch harness, PCM/BCM connector)
- Aftermarket remote starter, alarm, or bypass device improperly wired
- Faulty starter relay or stuck relay contacts supplying voltage unexpectedly
- Faulty PCM/BCM input circuit or internal damage
Symptoms
- Engine will not crank or intermittent cranking/no-crank
- Starter engages when not intended or cranks unexpectedly
- No-start or start/stop faults that correlate with key position
- Illumination of MIL or other warning indicators related to starting system
- Stored DTC P2535 (may be accompanied by other voltage or starter-related codes)
What to check
- Retrieve freeze frame and pending codes; note battery voltage when code set
- Visually inspect ignition switch connector, PCM/BCM connectors and wiring for damage, corrosion or aftermarket splices
- Check for recently installed remote starters, alarms, or bypass modules and verify their wiring
- Verify battery voltage and good battery terminals/ground connections
- Wiggle test wiring while observing voltage or scanning data to reproduce the fault
- Inspect starter relay and related fuses for signs of stuck contacts or damage
Signal parameters
- Expected: OFF ~0 V on ignition input (closed to ground or low reference depending on design)
- Expected: ON position ~ battery voltage (typically 12–14.5 V) at the feed, with the ignition sense input within module-specified thresholds
- Expected: START position should be at or near battery voltage when key is held to START
- Fault condition: input voltage higher than the module’s high threshold (varies by manufacturer) or unexpected voltage present when key is not in ON/START
Diagnostic algorithm
- Retrieve all stored codes and freeze-frame data. Note battery voltage and key position logged when the code set.
- Inspect wiring and connectors for the ignition switch, starter relay, and the PCM/BCM input connector for corrosion, broken pins, or aftermarket splices. Repair as needed.
- With a digital voltmeter, back-probe the ignition switch ON/START output and monitor voltage in each key position (OFF, ON, START). Compare to expected values and watch for voltage present where it shouldn't be.
- If voltage is present with key OFF, disconnect the ignition switch harness and re-check the circuit. If voltage disappears, suspect ignition switch or aftermarket device. If voltage remains, suspect short to battery downstream or module issue.
- Check continuity between ignition switch output and module input; check for unintended shorts to battery positive. Repair damaged wiring or insulation.
- Inspect and bench-test starter relay and associated fuses. Replace if contacts are stuck or intermittent.
- If wiring and relays check good, test or replace the ignition switch (or its module) per vehicle procedure. After replacement, clear codes and retest.
- If fault persists after wiring and switch replacement, consider module-level faults (PCM/BCM). Confirm with manufacturer procedures before replacing control modules.
- After repairs, erase codes and perform repeated key-in/on/start cycles to verify the issue is resolved and code does not return.
Likely causes
- Damaged wiring or short to battery on the ignition switch ON/START feed
- Faulty ignition switch contacts or internal failure
- Aftermarket remote start/anti-theft device introducing voltage when it shouldn’t
Fault status
Status
Ignition Switch ON/START circuit voltage is higher than the control module allows; module detected a high-voltage condition on the ignition input.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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