Checking the automatic transmission speed sensor with a multimeter
Required tools:
* Digital multimeter
* Connection cables
Verification procedure:
1. Locate the automatic transmission speed sensor. It is usually located on the transmission near the output shaft.
2. Disconnect the sensor connector. Be sure to mark which wire comes from which terminal.
3. Set the multimeter to resistance measurement mode.
4. Connect one multimeter probe to the positive terminal of the sensor (usually the white or purple wire).
5. Connect the other multimeter probe to the negative terminal of the sensor (usually the black or brown wire).
6. Rotate the transmission output shaft by hand.
7. Note the resistance reading as the shaft rotates.
Test results:
* The resistance should change as the shaft rotates. This indicates that the speed sensor is working.
*If the resistance remains constant, it may indicate a problem with the speed sensor or wiring.
* If the resistance is too high (infinity), this indicates an open in the speed sensor circuit.
*If the resistance is too low (0 ohms), it indicates a short circuit in the speed sensor.
If the speed sensor is faulty:
If the check shows that the speed sensor is faulty, it must be replaced. For proper installation and adjustment of the speed sensor, it is recommended that you consult your vehicle’s repair manual or consult a qualified mechanic.
Cautions:
* Always disconnect the battery when carrying out any work related to the vehicle’s electrical system.
* When handling electronic components, take precautions and use an antistatic wrist strap for grounding.
* Do not touch exposed electrical connections or components until the power has been turned off.