SureTrack Real Fix: Throttling Issue

Real Fixes from the SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is currently available free with the purchase of a current Snap-on® diagnostic software version.

The throttle body on vehicles controls the air provided to the engine for combustion. There several controls related to its function and when one goes bad the vehicle won’t run right. Follow this Real Fix to see how code P2101 was diagnosed on this vehicle and how the issue was resolved.

Vehicle
2019 Chevrolet Suburban LS 5.3L

Title
P2101, Replaced Throttle Body

Complaint
The customer states the check engine light is on.

Cause
Connected a scan tool and found code P2101 – Control Module Throttle Actuator Position Performance. With the scan tool connected cleared the codes. Engine running used the scan tool to monitor live data and found the throttle position sensor 1 (TP1) and the throttle position sensor 2 (TP2) specified TP1 4.0 to 0.1 Volt and TP2 0.1 to 4.0 Volt sensor signal parameters were erratic as the accelerator pedal was depressed. Commanded a throttle sweep with the scan tool, monitored the throttle position sensor signal parameters using the lab scope and found the throttle position sensor signal parameters produced an erratic signal and waveform pattern. Used the multi-meter to measure the specified 5 Volt reference and less than 100 mV ground found all were present at the throttle position sensor terminals. Performed a visual inspection of the throttle body connector, terminals and wiring harness, but found no obvious faults. Key on, engine off, used the lab scope to probe the connector for the throttle actuator control (TAC) motor 1 and the TAC motor 2. Voltage should be 12 Volts and polarity and waveform should reverse when throttle is snapped. Snapped the accelerator pedal and found the lab scope waveform was erratic. During snap transition, upward and downward pulses may be immediate or spaced between upward and downward waveform. Found the signal waveform had dropouts during the snap throttle indicating an internal fault in the TAC motor 1 and 2. With the intake tube removed, operated the throttle valve with the scan tool and found the throttle valve operation was erratic. The TAC motor is integrated into the throttle body and is replaced as an entire unit. The results of these tests verified the throttle body was faulty.

Correction
Replaced the throttle body, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.


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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.