Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTCS 21/22, TP Sensor Circuit High/Low (4L80-E With TCM): Notes
TP sensor contains a resistor strip with one end connected to a 5-volt supply and other to ground. Signal circuit is connected to a movable contact within TP sensor. As accelerator pedal is applied, voltage signal will increase from about .5 volt to 4.5 volts.
DTC 21 will set when:
- Engine operating.
- TP sensor signal voltage greater than 4.9 volts.
- Conditions met for one second.
DTC 22 will set when:
- Engine operating.
- TP sensor signal voltage less than .2 volts.
- Conditions met for one second.
TCM will default to maximum line pressure, use 35 percent throttle as default, and inhibit 4th gear if in hot mode.
- This test checks for presence of 5 volts at TP sensor.
- Scan tester should display 5-volt reference to TCM.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.