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Home / DTC / P2100 — Throttle Actuator Control Motor Circuit/Open

P2100 — Throttle Actuator Control Motor Circuit/Open

Detailed page for trouble code P2100.

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Code

P2100

MERCEDES-BENZ P — Powertrain

Throttle Actuator Control Motor Circuit/Open

Brand: MERCEDES-BENZ
Type: P — Powertrain
AI status
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Page language: EN

Causes

  • Broken or disconnected wiring in throttle actuator motor circuit
  • Corroded/loose connector at throttle actuator
  • Failed throttle actuator (motor) or internal open winding
  • Blown fuse or fusible link supplying throttle actuator circuit
  • Poor ground or power supply to throttle actuator/ECM
  • Faulty engine control module (less common)

Symptoms

  • Check Engine Light / MIL illuminated
  • Reduced engine power or limp-home mode
  • Poor throttle response or no throttle control input
  • Engine may idle poorly or not respond to accelerator
  • Stored/active throttle-related DTCs (P21xx / P21xx series)

What to check

  • Read freeze frame data and all stored/related DTCs with a scan tool
  • Visually inspect throttle body connector, wiring harness and routing for damage, corrosion or pinch points
  • Verify battery voltage is within normal range and battery is secure
  • Check fuses and fusible links related to throttle/ECM power
  • Back-probe throttle actuator connector pins and measure supply and ground with ignition ON and engine OFF
  • Measure continuity and resistance of motor windings and wiring to ECM with connectors disconnected

Signal parameters

  • Power supply: battery voltage present at throttle actuator power feed with ignition ON (approx. 11–14 V)
  • Ground: solid reference/ground continuity to chassis/ECM ground
  • Motor winding resistance: typically low ohms; expected non-infinite resistance (often in the 1–20 Ω range depending on design) — open/infinite indicates winding open
  • ECM drive: PWM/H-bridge output — back-probed drive may show switching; voltage should change when actuator is commanded
  • No high resistance: voltage drop between supply and actuator ground should be minimal under static load

Diagnostic algorithm

  1. Connect a scan tool, record freeze frame and note related codes. Clear codes and attempt to reproduce to confirm persistence.
  2. Visually inspect throttle body, connector, and wiring harness for damage, corrosion, loose pins, or signs of overheating or water entry.
  3. Check related fuses and relays; replace if blown and retest. Verify battery voltage is good.
  4. With ignition ON (engine OFF), back-probe the throttle actuator connector: check battery feed pin for ~12 V and ground/reference pin for continuity to chassis ground/ECM.
  5. Measure motor winding resistance at the throttle body connector with connector disconnected. Infinite or very high resistance indicates open winding — replace throttle actuator.
  6. Perform continuity/insulation checks on wiring between throttle actuator connector and ECM connector. Repair any open circuits or high-resistance sections.
  7. Command the throttle actuator using a scan tool (actuator calibration/drive test) while monitoring voltages and current if supported. Observe for correct movement and driver outputs from ECM.
  8. If wiring and actuator check OK, inspect ECM drive outputs at the ECU harness. If outputs are absent or shorted, consider ECM fault — consult manufacturer procedures before replacement.
  9. After repair, clear codes, perform throttle relearn/calibration as required by manufacturer, and perform road test to confirm fault is resolved.

Likely causes

  • Open or high-resistance motor windings in the throttle actuator
  • Damaged connector pins or corrosion at throttle body plug
  • Broken wire or chafed harness between ECM and throttle body
  • Blown fuse or interrupted power/ground feed to the actuator
  • Water ingress or contamination at connector causing open circuit

Fault status

⚠️ Status
Throttle actuator control motor circuit/open — open circuit in throttle motor drive; check wiring, connector and actuator motor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

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856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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