P2536 critical

Ignition Switch Run/Start Position Circuit Low

The P2536 code means the vehicle's onboard diagnostic system has detected: Ignition Switch Run/Start Position Circuit Low. This is a critical severity code.

My Garage →
Keep driving?
No -- stop driving
DIY difficulty
hard
Estimated cost
$150 - $700 (parts and labor)
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Common Symptoms

  • Engine cranks very briefly then stops
  • Start signal drops out during cranking
  • No start after extended cranking
  • Click sound from starter but engine doesn't turn

Probable Causes (Ranked by Likelihood)

  • Short to ground in start circuit wiring Very High
  • Failed ignition switch start contacts High
  • Starter solenoid pulling voltage too low Moderate
  • Corroded battery cable reducing start circuit voltage Low

Step-by-Step Diagnostic Procedure

  1. Measure voltage at ignition start circuit during crank attempt

  2. Check start circuit wiring for shorts to ground

  3. Test starter current draw for excessive amperage

  4. Clean and tighten battery terminals and ground straps

Frequently Asked Questions

Can a weak battery cause P2536?

A severely weak battery can drop system voltage during cranking, but P2536 specifically targets the ignition switch circuit. If battery and starter test good, focus on the switch and wiring.

What is the start circuit voltage supposed to be?

During cranking, the start circuit should maintain at least 10V on most vehicles. P2536 sets when voltage drops below the ECM threshold.

Could a bad starter motor cause this code?

A starter drawing excessive current can pull down the entire electrical system, potentially triggering P2536 along with slow or no cranking symptoms.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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