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.
1978 Subaru GF Automatic TransFACTORY OEM SERVICE PROCEDURE
All Models
- Measure resistance, using an ohmmeter, across "F" and "E" terminals for rotor coil resistance. Rotor coil circuit is normal if resistance is 4-5 ohms. If resistance is high, there is poor contact between brushes and commutator. If no continuity exists between "F" and "E" terminals, there is either an open rotor coil circuit, brush sticking or a broken lead wire. If resistance is low, it indicates a rotor coil layer short or grounded circuit.
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NOTE: The following test will not indicate a open state of the diodes. Tester will indicate a continuity regardless of diode conditions if tester leads are connected to the terminals with polarities reversed.
Connect positive lead of tester to alternator "N" terminal and tester negative lead to alternator "A" terminal. If continuity is observed on the tester, there exists one or more shorted positive diodes.
- Next, connect tester positive lead to alternator "E" terminal and tester negative lead to alternator "N" terminal. If continuity is present, it indicates that one or more of the negative diodes are shorted.
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.