Code
P2100
HUMMER
P — Powertrain
Throttle Actuator Control (TAC) Motor Control Circuit
Views:
UK: 13
EN: 17
RU: 36
AI status
Completed
Completed
100%
Causes
- Open or short in TAC motor wiring harness
- Corroded, loose or damaged connector(s) at throttle body
- Faulty throttle actuator (motor)
- Faulty PCM/ECM driver or ground
- Blown fuse or faulty relay for TAC power/ground
- Intermittent wiring fault or pinched wire
Symptoms
- Check Engine Light (MIL) on
- Reduced or inconsistent throttle response; limp-home mode
- Engine may only idle or run with limited throttle
- Possible stored related throttle/pedal position codes (mismatches)
What to check
- Read and record freeze frame and all stored DTCs with a scan tool
- Visual inspection of throttle body, connectors and wiring for damage, corrosion or looseness
- Check fuses and relays for throttle actuator/PCM circuits
- Backprobe the TAC motor connector and verify key-on battery voltage and ground presence
- Measure resistance of motor windings (with battery disconnected) and compare to spec
- Wiggle-test wiring while monitoring live data for intermittent changes
Signal parameters
- Supply voltage at throttle actuator power pin: ~11–14.5 V (key ON) — vehicle specific
- Motor winding resistance (typical range): a few ohms to tens of ohms (check service manual)
- Control signal: PWM duty cycle 0–100% commanded by PCM (frequency varies by design, typically hundreds of Hz)
- High resistance/open: OL or very high ohms; short to battery: near 0 Ω to battery potential; short to ground: near 0 Ω to ground
Diagnostic algorithm
- Retrieve DTCs and freeze frame with a scan tool; note any related codes (pedal position, throttle position)
- Perform a visual inspection of throttle body, wiring harness and connector for damage, corrosion, heat damage or oil contamination
- Check relevant fuses/relays for continuity and correct operation
- With battery connected and key ON (engine off), backprobe the TAC motor connector: verify battery voltage at the power pin and good chassis/PCM ground at ground pin
- Using a DVOM, measure motor winding resistance with battery disconnected; compare to manufacturer specification (high or open indicates motor or wiring open)
- With scan tool, command TAC motor (actuator test) and observe response and live data for commanded duty and actual throttle position; listen for motor operation
- If wiring is suspected, perform continuity checks between the TAC connector and PCM pins for opens/shorts; check for short to battery or ground
- If PWM or driver faults suspected, use an oscilloscope to view the PCM output while commanding the actuator (look for proper PWM and no clipping or stuck outputs)
- If wiring and connectors are good but motor fails tests, replace the throttle body/actuator assembly and retest
- Clear codes and road-test; if code returns, consider PCM/ECM testing or replacement as a last step per factory procedure
Likely causes
- Poor connector pin contact at throttle body
- Broken or chafed wire to TAC motor (open/short to battery or ground)
- Failed throttle actuator motor windings or internal driver
- Faulty PCM driver (less common)
Fault status
Status
P2100 — Throttle Actuator Control (TAC) Motor Control Circuit: electrical fault detected in the actuator motor control (open/short/high resistance/intermittent). Inspect wiring, connector, fuses/relays, motor, and PCM driver.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email