Code
P2101
HUMMER
P — Powertrain
Control Module Throttle Actuator Position Performance
AI status
Completed
Completed
100%
Causes
- Contaminated or mechanically binding throttle body (carbon build-up on throttle plate/shaft)
- Faulty electronic throttle actuator (motor/gear wear)
- Faulty throttle position sensor(s) or sensor circuit
- Damaged wiring, poor connectors, or intermittent open/short in actuator/feedback circuits
- Low or unstable battery/charging system voltage
- ECM/software calibration or software fault
Symptoms
- Check Engine Light (MIL) illuminated
- Reduced engine power / limp-home mode
- Delayed, sluggish, or inconsistent throttle response
- Engine may idle poorly, surge, or stall
- Throttle may feel unresponsive or stick at partial positions
What to check
- Read freeze-frame and live data with a capable scan tool; record commanded throttle position vs. actual/throttle angle feedback
- Verify battery voltage at rest and during cranking; ensure proper charging system voltage (typically ~13.5–14.8 V with engine running)
- Inspect throttle body for carbon build-up, mechanical binding, or obstructions
- Visually inspect wiring and multi-pin connectors at throttle body and ECM for corrosion, bent pins, or damage
- Check for additional related DTCs (P2100–P2119 family, P2138, P0120, etc.)
- Perform an actuator self-test or closed-loop feedback test if supported by scan tool
Signal parameters
- Commanded throttle position (percent or degrees) vs. actual/throttle position sensor — should track closely (typical tolerance ~±5–10%)
- Throttle position sensor voltage typically within ~0.5–4.5 V range across pedal/throttle travel; signal should change smoothly without jumps
- Actuator supply/reference voltage ~5 V for sensors; motor drive may use battery voltage — verify stable supply (~12 V while running)
- No rapid fluctuations or intermittent dropouts in feedback PIDs; no stuck-at values when pedal/command changes
Diagnostic algorithm
- Connect scan tool, retrieve P2101 and any related codes, save freeze-frame and live data for commanded vs actual throttle position while performing pedal inputs.
- Verify battery and charging system voltage. Charge or replace battery if low and retest.
- Visually inspect throttle body, actuator and wiring harness for contamination, damage, or loose connectors. Repair as needed.
- With ignition on (engine off), cycle throttle via scan tool actuator test. Observe actuator movement and feedback for smooth, full-range operation.
- If the throttle plate is dirty or binding, clean throttle body and shaft with approved throttle-body cleaner, then recheck operation.
- Check continuity and resistance of sensor and motor circuits per vehicle service manual. Repair any open/shorts or high resistance connections.
- If wiring and connectors are good but feedback does not follow commanded position, replace the throttle body/actuator assembly per manufacturer procedures.
- After repair or replacement, perform throttle/ECM relearn or adaptation procedure as required by HUMMER service instructions.
- Clear codes and road test while monitoring commanded vs actual throttle PIDs to confirm fault absence.
- If fault persists after actuator replacement and wiring checks, consider ECM software update or ECM replacement as a last step.
Likely causes
- Throttle body binding or heavy carbon deposits preventing plate from reaching commanded angle
- Faulty throttle actuator motor or internal gear failure preventing accurate movement
- Wiring harness damage or poor connector making feedback intermittent or out-of-range
- Faulty throttle position sensor(s) producing incorrect feedback voltage
- Battery/charging voltage low during throttle operation causing control anomalies
Fault status
Status
Throttle actuator position performance fault detected. ECM indicates actual throttle position does not match commanded position. Possible limp-mode and reduced engine power.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
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Repair manuals
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138
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