Oem Electrical Troubleshooting & Wiring System: Overview Subaru Forester SJ

GENERAL DESCRIPTION

The most important purpose of diagnostics is to quickly determine which fault is the root cause of the symptom, to save time and labor.

IDENTIFICATION OF TROUBLE CAUSE

1. Using the diagnostics, narrow down the causes.
2. Refer to the wiring diagram and check the system's circuit. If necessary, use a voltmeter, ohmmeter, etc.
3. Before replacing component parts, check for fuse blowout, open wiring harness on the power supply circuit and the ground circuit, and poor connectors, switches, relays, etc. If no problem is encountered, check the component parts.

SYSTEM OPERATION CHECK

After inspection and repair, ensure that the system operates properly.

Scheme 1

1. Using a voltmeter, connect the negative lead to a good ground point or negative battery terminal. Connect the positive lead to the connector or component terminal.
2. Contact the positive lead of the voltmeter on connector (A). The voltmeter will indicate a voltage.
3. Shift the positive lead contacting the connector (A) to the connector (B). The voltmeter will indicate no voltage.
4. Turn the switch to ON with the positive lead contacting the connector (B). The voltmeter will indicate a voltage and, at the same time, the light will illuminate.
5. The circuit is normal. If a problem such as a light failing to illuminate occurs, use the procedures above to track down the malfunction.

Scheme 2

Scheme 3

1. Disconnect the battery terminal or connector so there is no voltage between the check points. Contact the leads of an ohmmeter between the check points, and check that there is continuity.
2. When checking the diode continuity using an ohmmeter, allow the positive lead to contact the diode positive side and the negative lead to the negative side. At this time, there must be continuity. Also, when contacting the leads in reverse, there should be no continuity. NOTE: Some testers have reverse polarity, therefore, refer to the instruction manual of the tester.
3. When checking switch continuity using an ohmmeter, perform the check while the switch operates. For example, when a switch position is at 3, continuity exists among terminals 1, 3 and 6, as shown below.

Scheme 4

Scheme 5

1. With voltmeter: An open circuit is determined by measuring the voltage between respective connectors and ground using a voltmeter, starting with the connector closest to the power supply. The power supply must be turned ON so that current flows in the circuit. If voltage is not present between a particular connector and ground, the circuit between that connector and the previously checked point is open.
2. With ohmmeter: Disconnect all connectors affected, and check continuity in the harness between adjacent connectors. When the ohmmeter indicates "infinite", the harness is open.

Scheme 6

Scheme 7

1. With test light: Connect a test light (rated at approx. 3 watts) in place of the blown fuse and allow current to flow through the circuit. Disconnect one connector at a time. At that time, always start with the connector located farthest from the power supply. If the test light goes out when a connector is disconnected, the harness between that connector and the next connector (farther from the power supply) is shorted.
2. With ohmmeter: Disconnect all affected connectors, and check continuity between each connector and ground. When the ohmmeter indicates continuity between a particular connector and a ground, that connector is shorted.

ABBREVIATIONS IN THIS INFORMATION