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.
Inspection For PCM Power Circuit
- Turn IGN switch ON.
- Check the PCM engine relay "ON" power terminal voltage value using a multi-tester.
- If the voltage is faulty, Inspection For wiring harness.
List of Inspection Normal value Inspection Condition Probe (+) Probe (-) Engine Relay ON ←→ PCM supply power About 12V (battery voltage) 1. IGN Switch "ON" PCM Connector side
1. Main relay "ON" powerChassis Ground Engine Relay ON ←→ PCM supply power PCM Connector side
2. Main relay "ON" powerChassis Ground
Information
Engine relay ON The faulty part according to the power cable inspection can be predicted as follows:
| Measurement Result | Possible Cause |
|---|---|
| When voltage is not output | Wire break/"ECU1" fuse/"PCB-C" intermediate connector/PCB block needs to be checked |
| When output below the specified voltage | Battery check/Wiring check required |
| At about 0V output | Short to the wiring harness/ground (chassis) |
OK
Go to "Inspection For PCM Ground Circuit" procedure.
NG
Go to "Inspection For PCM Power Circuit Open/Short Circuit" procedure.
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.