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.

2005 Subaru Outback RFACTORY OEM SERVICE PROCEDURE

Starting/Charging Systems (H4SO): Generator: Inspection: Diode

CAUTION: Never use a mega tester (designed for reading high voltage) or any other similar instrument for this test; otherwise, the diodes may be damaged.

Checking positive diode Check for continuity between the diode lead and positive side heat sink. The positive diode is in good condition if resistance is 1 Ω or less only in the direction from the diode lead to heat sink.

Fig 1: Checking Continuity Between Diode Lead And Positive Side Heat Sink
Courtesy of SUBARU OF AMERICA, INC.
Checking negative diode

Check for continuity between the negative side heat sink and diode lead. The negative diode is in good condition if resistance is 1 Ω or less only in the direction from the heat sink to diode lead.

Fig 2: Checking Continuity Between Negative Side Heat Sink And Diode Lead

Courtesy of SUBARU OF AMERICA, INC.

Factory Service Tools

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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.