Mitsubishi Outlander: How To Diagnose (Electrical)

HOW TO DIAGNOSE

The most important point in troubleshooting is to determine "Probable Cause". Once the probable causes are determined, parts to be checked can be limited to those associated with such probable causes. The determination of the probable causes must be based on a theory and be supported by facts and must not be based on intuition only.

TROUBLESHOOTING STEPS

If an attempt is made to solve a problem without going through correct steps for troubleshooting, the symptoms could become more complicated, resulting in failure to determine the causes correctly and making incorrect repairs. The four steps below should be followed in troubleshooting.

INFORMATION FOR DIAGNOSIS

This manual contains the harness diagrams as well as the individual circuit drawings, operational explanations, and troubleshooting hints for each component. The information is presented in the following manner:

1. Connector diagrams show the connector positions, etc., on the actual vehicle as well as the harness path.

2. Circuit diagrams show the configuration of the circuit with all switches in their normal positions.

3. Operational explanations include circuit drawings of current flow when the switch is operated and how the component reacts.

4. Troubleshooting hints include numerous examples of problems which might occur, traced backward in a common-sense manner to the origin of the trouble. Problems whose origins may not be found in this manner are pursued through the various system circuits.

NOTE: Components of MFI, ETACS, etc. with ECU do not include 3 and 4 above. For this information, refer to a relevant group which includes details of these components.

INSPECTION

1. Sight and sound checks

Check relay operation, blower motor rotation, light illumination, etc. Listen for a "click" when some relay covers are pushed down.

2. Simple checks

For example, if a headlight does not come on and a faulty fuse or poor grounding is suspected, replace the fuse with a new one. Or use a jumper wire to ground the light to the body. Determine which part(s) is/are responsible for the problem.

3. Checking with instruments

Use an appropriate instrument in an adequate range and read the indication correctly.

INSPECTION INSTRUMENTS

For inspection, use the following instruments:

CAUTION

Never use a test light for checking ECU-related circuits or ECUs.

1. Test light

A test light consists of a 12V bulb and lead wires. It is used to check voltages or short circuits.

2. Self-powered test light

A self-powered test light consists of a bulb, battery and lead wires connected in series. It is used to check continuity or grounding.

CAUTION

Never use a jumper wire to connect a power supply directly to a load.

3. Jumper wire

A jumper wire is used to close an open circuit.

4. Voltmeter

A voltmeter is used to measure the circuit voltage. Normally, the positive (red lead) probe is applied to the point of voltage measurement and the negative (black lead) probe to the body ground. Use a digital voltmeter to check for voltage drop before or after a component.

5. Ohmmeter

An ohmmeter is used to check continuity or measure resistance of a switch or coil. If the measuring range has been changed, the zero point must be adjusted before measurement.

CHECKING FUSES

A blade type fuse has test taps provided to allow checking of the fuse itself without removing it from the fuse block. The fuse is okay if the test light comes on when its one lead is connected to the test taps (one at a time) and the other lead is grounded.

Remember to turn the ignition switch to ON to ensure all circuits are live.

CAUTIONS IN EVENT OF BLOWN FUSE

When a fuse is blown, there are two probable causes. One is that it is blown due to flow of current exceeding its rating. The other is that it is blown due to repeated on/off current flowing through it. Which of the two causes is responsible can be easily determined by visual check as described below.

1. Fuse blown due to current exceeding rating The illustration shows the state of a fuse blown due to this cause. In this case, do not replace the fuse with a new one hastily since a current heavy enough to blow the fuse has flowed through it. First, check the circuit for shorts and check for abnormal electric parts. After correcting shorts or replacing parts, use only a fuse of the same capacity as a replacement. Never use a fuse of larger capacity than the original fuse. If a larger capacity fuse is used, electric parts or wiring could be damaged, or could start a fire.

2. Fuse blown due to repeated turning current on and off The illustration shows the state of a fuse blown due to repeated current on/off. Normally, this type of problem occurs after a fairly long period of use and is less frequent than above. In this case, simply replace with a new fuse of the same capacity.

CHECKING SWITCHES

In a circuit diagram, a switch is shown in the idle state.

1. Normally open or normally closed switch

Switches are classified into those which open the circuit and those which close the circuit when off.

Switches are shown in their normal state unless specified otherwise.

2. Switch connection

This figure illustrates a complex switch. The continuity between terminals at each position is as indicated in the table below.

CHECKING RELAYS

1. By using a relay, a heavy current can be turned on and off by a switch using much less current. For example, in the circuit shown here, when the switch is turned on (closed), current flows to the coil of the relay. Then, its contact is turned on (closed) and the light comes on. The current flowing through the switch is much less than that for the light.

2. When current flows through the coil of a relay, its core is magnetized to attract the iron piece, closing (ON) the contact at the tip of the iron piece. When the coil current is turned off, the iron piece returns to its original position by a spring, opening the contact (OFF).

3. Relays may be classified as the normally open-type or the normally closed-type, depending on their contact construction.

NOTE: The deenergized state means that no current is flowing through the coil. The energized state means that current is flowing through the coil.

1. The normally open-type
   When a normally open relay as illustrated here is checked, there should be no continuity between terminals 3 and 4 when the relay is deenergized. There should be continuity between terminals 3 and 4 when battery voltage and ground are applied to terminals 1 and 2. The relay condition is determined by this check.

NOTE: Check the relay in both situation which is energized and is not energized.

2. The normally closed-type
   When a normally closed relay as illustrated here is checked, there should be continuity between terminals 3 and 4 when the relay is deenergized. There should be no continuity between terminals 3 and 4 when battery voltage and ground are applied to terminals 1 and 2. The relay condition is determined by this check.

NOTE: Check the relay in both situation which is energized and is not energized.

CABLES AND WIRES CHECK

1. Check connections for looseness, rust, and stains.

2. Check terminals and wires for corrosion.

3. Check terminals and wires for open circuit or impending open circuit.

4. Check wire insulation and coating for damage, cracks, and wear.

5. Check conductive parts of terminals for contact with other metallic parts (vehicle body and other parts).

6. Check grounding parts to verify that there is complete continuity between attaching bolt(s) and vehicle body.

7. Check for incorrect wiring.

8. Check that harnesses are secured to prevent contact with sharp edges and corners or hot parts (exhaust manifold, pipe, etc.).

9. Check that harnesses are secured firmly to provide enough clearance from the fan pulley, fan belt, and other rotating or moving parts.

10.Check that the harnesses between fixed parts (such as the vehicle body) and vibrating parts (such as the engine) are long enough to allow for vibration and movement.

BATTERY HANDLING

WARNING

Battery posts, terminals and related accessories contain lead and lead compounds. WASH HANDS AFTER HANDLING.

When checking or servicing does not require power from the vehicle battery, be sure to disconnect the cable from the battery (−) terminal. This will prevent problems that could be caused by a short circuit. Disconnect the (−) battery terminal first and reconnect it last.

GENERAL ELECTRICAL SYSTEM CHECK

A circuit consists of the power supply, switch, relay, load, ground, etc. There are various methods to check a circuit including an overall check, voltage check, short-circuit check, and continuity check. Each of the methods briefly described below applies only to circuits similar to the illustration.

1. VOLTAGE CHECK

1. Ground one lead wire of the test light. If a voltmeter is used instead of the test light, ground the grounding side lead wire.
2. Connect the other lead wire of the test light to the power side terminal of the switch connector. The test light should come on or the voltmeter should indicate a voltage.
3. Then, connect the test light or voltmeter to the motor connector. The test light should not come on, or the voltmeter should indicate no voltage. When the switch is turned ON in this state, the test light should come on, or the voltmeter should indicate a voltage, with the motor starting to run.
4. The circuit illustrated here is normal. If there is any problem, such as the motor failing to run, check voltages beginning at the connector nearest to the motor until the faulty part is identified.

2. SHORT-CIRCUIT CHECK

Because the fuse has blown, it is probable that there is a short circuit. Follow the procedures below to narrow down the short-circuit location.

STEP 1. Remove the blown fuse and connect the test light across the fuse terminals (Circuit switch: OFF).

Q: Does the test light illuminate?

YES : Short-circuit exists between the fuse block and the switch. Repair the harness between the fuse block and the switch.

NO : Go to Step 2.

STEP 2. Turn the switch ON and disconnect the illumination light connector.

Q: Does the test light illuminate?

YES : Short-circuit exists between the switch and the connector. Repair the harness between the switch and the connector.

NO : Short-circuit exists between the connector and the illumination light. Repair the harness between the connector and the illumination light.

3. CONTINUITY CHECK

1. When the switch is in the "OFF" position and the contact points of terminals 1 and 2 are connected, the self-powered test light should illuminate or the ohmmeter should read 0 ohm.
2. When the switch is the "ON" position and the contact points of terminals 3 and 4 are connected, the self-powered test light should come on or the ohmmeter should read 0 ohm.

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