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Home / DTC / C1506 — Idle Switch | Closed Throttle Position Switch

C1506 — Idle Switch | Closed Throttle Position Switch

Detailed page for trouble code C1506.

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Code

C1506

HYUNDAI C — Chassis

Idle Switch | Closed Throttle Position Switch

Brand: HYUNDAI
Type: C — Chassis
AI status
Completed
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Page language: EN

Causes

  • Faulty idle/closed-throttle position switch
  • Damaged, corroded or disconnected connector or wiring (open, short to voltage or ground)
  • Contaminated or mechanically sticking throttle body / switch
  • Incorrect switch adjustment or misaligned throttle stop
  • Faulty PCM/ECM or poor ground at control module
  • Intermittent wiring damage from chafing, heat or moisture

Symptoms

  • Check Engine Light or warning lamp illuminated
  • Engine idle unstable, rough idle or higher-than-normal idle speed
  • Engine may stall at idle or on deceleration
  • Reduced or delayed throttle response; possible limp-home mode on some vehicles
  • Cruise control inoperative (on some models)
  • DTC stored in freeze frame when condition observed

What to check

  • Retrieve DTC and freeze-frame data with a scan tool; verify C1506 is current or historical
  • Visually inspect throttle body, idle switch connector and wiring for damage, corrosion, or loose pins
  • Check for related codes (powertrain/ECM throttle codes) that may give context
  • Backprobe the idle switch connector and monitor signal while slowly closing/opening throttle (or using a scan tool)
  • Measure reference power and ground at the switch connector (typically a 5V reference and ground)
  • Check continuity between the switch connector and PCM pins; check for shorts to power/ground

Signal parameters

  • Signal type: digital (ON/OFF) switch indicating throttle closed/idling
  • Typical wiring: reference (5V) or ignition-switched supply, signal return to PCM, and ground (verify with factory data)
  • Closed position: switch changes state (logical HIGH or LOW) when throttle reaches closed position — consult Hyundai service manual for exact polarity
  • Switch transition should be consistent and instantaneous when throttle plate reaches closed position

Diagnostic algorithm

  1. Connect a scan tool, confirm C1506 and view live data while cycling the throttle to observe closed-throttle switch status.
  2. Visually inspect the throttle body, idle switch connector and harness for damage, corrosion, rips or pinched wiring.
  3. With ignition ON (engine off) or as directed by factory procedure, backprobe the switch connector: verify reference voltage, signal voltage and ground presence. Compare to specs.
  4. Slowly operate the throttle and observe the switch signal state change. If signal does not change at the expected throttle position, test switch continuity with a multimeter per service manual.
  5. If wiring or connector faults are found, repair/replace damaged wiring or connector and retest. If intermittent, perform wiggle test and secure harness.
  6. If wiring and connector are good but switch fails spec, replace the idle/closed-throttle position switch and retest.
  7. After repair, clear DTCs, perform a drive or idle test to ensure code does not return. If C1506 persists, consider throttle body assembly replacement or further ECM diagnosis with factory tools.
  8. If multiple unrelated throttle/TP sensor codes are present, follow manufacturer procedure for throttle/pedal position sensor relearn and ECM checks.

Likely causes

  • Switch contacts worn or stuck from contamination
  • Connector pins corroded or bent causing poor continuity
  • Broken/shorted harness between throttle body and ECM
  • Throttle body return spring weak or binding preventing full closure
  • Aftermarket modifications or improper reassembly after service

Fault status

⚠️ Status
Closed throttle position (idle) switch signal not as expected — closed-throttle switch circuit malfunction detected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

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371

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