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.
DTC 71, Camshaft Position Sensor Circuit Low (4L80-E W/ TCM): Notes
Camshaft position sensor detects rotational speed of camshaft. As camshaft rotates, an AC signal is generated in circuit. This signal provides input to determine engine speed, for use in various calculations including TCC slip speed and overdrive ratio. DTC 71 will set when:
- DTC 28 is not set.
- Engine speed less than 50 RPM.
- Trans. range indicates Reverse, D4, D3 or D1.
- Conditions are met for 2 seconds. PCM will default to inhibit TCC.NOTE: Test numbers refer to numbers on diagnostic chart.
- An out-of-range trans. range pressure switch could falsely indicate actual transmission range.
- This checks entire CMP sensor circuit for proper signal.
- A signal at this point indicates sensor is capable of inducing an AC voltage in circuit.
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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.
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