P1120 GMC Possible Causes
- Faulty throttle position sensor
- Throttle position sensor harness is open or shorted
- Poor electrical connection in throttle position sensor circuit
- Improperly adjusted throttle position sensor
How to Fix P1120 GMC Code?
Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
When is the Code Detected?
When the Powertrain Control Module (PCM) detects a signal voltage higher than the normal operating range of the sensor, P1120 sets.
Possible Symptoms
Illuminated MIL (Malfunction Indicator Light)
P1120 GMC Meaning
The Throttle Position (TP) sensor is a potentiometer. The TP sensor provides a voltage signal that changes relative to throttle blade angle. This signal voltage is one of the most important inputs used by the Powertrain Control Module (PCM). The TP sensor has a 5.0 volt reference, ground, and signal circuit.
TP sensor signal voltage should be approximately 0.6 volt at idle. TP sensor voltage should increase to over 4.0 volts at wide open throttle (WOT).