Subaru Forester SG 2002–2008 Wiring Diagram. Electrical System

Welcome to the section dedicated to the Subaru Forester SG (2002–2008) Wiring Diagram. Here you will find detailed information about key electrical components, including the battery, alternator, starter, fuses, relays, sensors, and basic wire connections.

The vehicle's electrical system plays an important role in its reliable and stable operation. Our diagrams will help you:

Understand the structure of the electrical wiring

Find the necessary connectors and fuses

Troubleshoot possible malfunctions

Carry out diagnostics and repair of electrical equipment

If you are engaged in independent repairs or work in a service center, this information will be an excellent assistant in working with the second-generation Forester SG.

• 🚗 Diagrams and descriptions
• 📌 Designations and color coding of wires
• 🔧 Tips for diagnosing faults

Are you ready to understand the wiring of your Forester? Then let's get started! ⚡

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• Forester SG 2002–2008 Workshop Manual>>

1. Generator and battery charging issues

Symptoms:

Battery charging is unstable or absent

Battery charging light on the dashboard is on

Car starts poorly

Causes and solutions:

✅ Worn brushes or diode bridge → replace worn parts

✅ Damaged or oxidized generator wires → clean or replace

✅ Generator belt issues → check tension, replace if necessary

2. Fuse and relay box malfunctions

Symptoms:

Some electrical systems (headlights, windows, fans) do not work

Fuses blow for no apparent reason

Periodic tripping and shutdown of systems

Causes and solutions:

✅ Oxidation of contacts in the fuse box → clean contacts, treat with dielectric grease

✅ Short circuit in wiring → test the circuit multimeter, replace the damaged section

✅ Relay failure → replace the relay

3. Problems with headlights and exterior lighting

Symptoms:

Headlights flicker or do not light

Two lamps light at once (if there are no working fuses)

Side lights or brake lights do not work

Causes and solutions:

✅ Oxidation of headlight connector contacts → clean and treat with grease

✅ Damaged wiring (especially in the area of the front bumper) → replace damaged wires

✅ Problems with the headlight relay → replace

4. Errors and failures of engine sensors

Symptoms:

Check Engine lights up

Floating engine speed

Misfires or unstable engine operation

Causes and solutions:

✅ Crankshaft or camshaft sensor failure → check resistance, replace if necessary

✅ Oxidation or damage to sensor connectors → clean or replace

✅ Broken sensor wiring → ring the circuit, replace damaged sections

5. Malfunction of the central lock and window lifters

Symptoms:

Window lifters work intermittently or do not work

Central lock does not open/close doors

Window lifter control buttons do not respond

Causes and solutions:

✅ Broken wires in the door corrugation → open the harness, restore connections

✅ Oxidation of control buttons → disassemble, clean contacts

✅ Failure of the window lifter motor → replace

✔ Check the battery terminals regularly – oxidation of the contacts can cause electronics to malfunction.

✔ Monitor the wiring in the engine compartment – vibrations can cause wires to wear out or break.

✔ Use a multimeter for diagnostics – this will help quickly identify breaks and short circuits.

✔ Check the fuse box – if a fuse constantly blows, there is a short circuit or overload somewhere.

✔ Use high-quality components – cheap fuses and relays can quickly fail.

If you have electrical problems, try checking the contacts, fuses and wiring first before replacing expensive components.