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.
Test Step 8 - Sensor Ground Circuit High Resistance
- Turn the ignition off.
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.
- Using a voltmeter, perform a voltage drop test by backprobing the sensor ground circuit at the sensor harness connector and at the applicable module connector (or by probing the appropriate terminal of the special tool #8815). Make sure the voltmeter leads are connected so that positive polarity is displayed on the voltmeter.
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
- Start the engine.
Is the voltage less than 0.5 volts?
Yes
- Go to Test Step TEST STEP 9 - CONTROL MODULE TEST .
No
- Repair the sensor ground circuit for high resistance.
- Perform the PCM Verification Test. Refer to PCM VERIFICATION TEST .
NO RELATED
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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.