HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS

Troubleshooting of electronic control systems for which the MUT-II can be used follows the basic outline described below. Even in systems for which the MUT-II cannot be used, some of these systems still follow this outline.

1. STANDARD FLOW OF DIAGNOSTIC TROUBLESHOOTING

Troubleshooting sections are based on the diagnostic flow as below. If the diagnostic flow is different from that given below, or if additional explanation is required, the details of such differences or additions will also be listed.

Diagnosis method

2. SYSTEM OPERATION AND SYMPTOM VERIFICATION TESTS

If verification of the symptom(s) is difficult, procedures for checking operation and verifying symptoms are shown.

3. DIAGNOSIS FUNCTION

Details which are different from those in the "Diagnosis function

" section are described.

4. DIAGNOSIS CODE CHART

Diagnostic trouble codes and diagnostic items are shown.

5. DIAGNOSIS CODE PROCEDURES

Indicates the inspection procedures corresponding to each diagnosis code (Refer to How to read inspection procedure

6. TROUBLE SYMPTOM CHART

If there are trouble symptoms even though the MUT-II does not find any diagnosis codes, Inspection procedures for each trouble symptom will be found by means of this chart.

7. SYMPTOM PROCEDURES

Indicates the inspection procedures corresponding to each symptoms classified in the Symptom Chart (Refer to How to read inspection procedure

8. SERVICE DATA REFERENCE TABLE

Inspection items and normal judgment values have been provided in this chart as reference information.

9. CHECK AT ECU TERMINALS

Terminal numbers for the ECU connectors, inspection items, and judgment values have been provided in this chart as reference information.

10. INSPECTION PROCEDURE BY USING AN OSCILLOSCOPE

When there are inspection procedures using an oscilloscope, these are described here.

DIAGNOSIS FUNCTION

HOW TO READ DIAGNOSIS CODE

CAUTION

Before connecting or disconnecting the MUT-II/III, turn the ignition switch to the "LOCK" (OFF) position.

Connect the MUT-II to the diagnosis connector, and read the diagnosis code.

Connect the MUT-III to the 16-pin diagnosis connector, and read the diagnosis code.

NOTE: For details on how to use the MUT-III, refer to the "MUT-III operation manual."

Ensure that the ignition switch is at the LOCK (OFF).

Start up the personal computer.

Connect MUT-III USB cable MB991827 to special tool Vehicle Communication Interface (V.C.I.) MB991824 and the personal computer.

Connect MUT-III main harness B MB991911 to the V.C.I.

Connect MUT-III main harness B to the diagnosis connector.

Turn the V.C.I. power switch to the ON position.

NOTE: When the V.C.I. is energized, the V.C.I. indicator lamp will be illuminated in a green colour.

Start the MUT-III system on the PC and turn the ignition switch to the ON position.

Read the diagnosis code.

Disconnecting the MUT-III is the reverse of the connecting sequence, making sure that the ignition switch is at the LOCK (OFF).

NOTE: The ABS warning lamp may flash when the ignition switch is turned ON with the MUT-II/III connected. This is because the diagnosis display function of the ABS warning lamp is activated by grounding the diagnosis connector terminal No.1, and is not detrimental in any way.

ERASING DIAGNOSIS CODE (BY USING THE MUT-II/III)

CAUTION

Before connecting or disconnecting the MUT-II/III, turn the ignition switch to the "LOCK" (OFF) position.

Connect the MUT-II/III to the diagnosis connector, and erase the diagnosis code. The procedure is the same as "HOW TO READ DIAGNOSIS CODE

ERASING DIAGNOSIS CODE (BY USING NO MUT-II/III)

CAUTION

Some diagnosis codes can not be erased according to the procedure below. If you attempt to erase a diagnosis code, refer to an applicable GROUP.

Turn the ignition switch to the "LOCK" (OFF) position.

Disconnect the negative battery cable, wait for at least 10 minutes, and then reconnect it.

Start the engine and let it run at idle for 10 minutes.

INPUT SIGNAL CHECK (WHEN USING THE MUT-II/III) <SWS>

CAUTION

Before connecting or disconnecting the MUT-II/III, turn the ignition switch to the "LOCK" (OFF) position.

Connect the MUT-II/III to the diagnosis connector, and erase the diagnosis code.

If the MUT-II/III buzzer sounds once when each switch is operated (ON/OFF), the input signal for that switch circuit system is normal.

INPUT SIGNAL CHECK (WHEN USING A VOLTMETER) <SWS>

Use the special tool diagnosis code check harness (MB991529) to connect the ETACS terminal (terminal 9) and the earth terminals (terminals 4 and 5) of the diagnosis connector to the voltmeter.

If the needle of the voltmeter flickers once when each switch is operated (ON/OFF), the input signal for that switch circuit system is normal.

HOW TO USE THE INSPECTION PROCEDURES

The causes of many of the problems occurring in electric circuitry are generally the connectors, components, the ECU, the wiring harnesses between connectors, in that order. These inspection procedures follow this order. They first try to discover a problem with a connector or a defective component.

HARNESS CHECK

Check for an open or short circuit in the harness between the terminals which were faulty according to the connector measurements. Carry out this inspection while referring to the Electrical Wiring Manual. Here, "Check the wiring harness between the power supply and terminal xx" also includes checking for blown fuse. For inspection service points when there is a blown fuse, refer to "Inspection Service Points for a Blown Fuse ."

MEASURES TO TAKE AFTER REPLACING THE ECU

If the trouble symptoms have not disappeared even after replacing the ECU, repeat the inspection procedure from the beginning.

CONNECTOR MEASUREMENT SERVICE POINTS

Turn the ignition switch to the "LOCK" (OFF) position when connecting and disconnecting the connectors. Turn the ignition switch to "ON" when measuring, unless there are instructions to the contrary.

IF INSPECTING WITH THE CONNECTOR CONNECTED

Be sure to use special tool harness connector (MD998459). Never insert a test probe from the harness side, as this will reduce the waterproof performance and result in corrosion.

Check by inserting the multi-meter test probe from the harness side. Note that if the connector (control unit, etc.) is too small to permit insertion of the test probe, it should not be forced; use the backprobing tool for this purpose.

IF INSPECTING WITH THE CONNECTOR DISCONNECTED

Use the special tool inspection harness (MB991219) (inspection harness for connector pin contact pressure in the harness set for inspection). The inspection harness for connector pin contact pressure should be used. the test bar should never be forcibly inserted, as it may cause a defective contact.

CAUTION

At this time, be careful not to short the connector pins with the test bars. To do so may damage the circuits inside the ECU.

Touch the pin directly with the test bar.

CONNECTOR INSPECTION SERVICE POINTS

VISUAL INSPECTION

Connector is disconnected or improperly connected

Connector pins are pulled out

Due to harness tension at terminal section

Low contact pressure between male and female terminals

Low connection pressure due to rusted terminals or foreign matter lodged in terminals

CONNECTOR PIN INSPECTION

If the connector pin stopper is damaged, the terminal connections (male and female pins) will not be perfect even if the connector body is connected, and the pins may pull out of the reverse side of the connector. Therefore, gently pull the harnesses one by one to make sure that no pins pull out of the connector.

CONNECTOR ENGAGEMENT INSPECTION

Use the special tool inspection harness (MB991219) (connector pin connection pressure inspection harness of the inspection harness set) to inspect the engagement of the male pins and females pins. (Pin drawing force: 1 N or more)

INSPECTION SERVICE POINTS FOR A BLOWN FUSE

Remove the blown fuse and measure the resistance between the load side of the blown fuse and the earth. Close the switches of all circuits which are connected to this fuse. If the resistance is almost 0 Ω at this time, there is a short somewhere between these switches and the load. If the resistance is not 0 Ω, there is no short at the present time, but a momentary short has probably caused the fuse to blow.
The main causes of a short circuit are the following.

Harness being clamped by the vehicle body

Damage to the outer casing of the harness due to wear or heat

Water getting into the connector or circuitry

Human error (mistakenly shorting a circuit, etc.)

HOW TO COPE WITH INTERMITTENT MALFUNCTIONS

NOTE: If determining the cause is difficult, the flight recorder function of the MUT-II can also be used.

Intermittent malfunctions often occur under certain conditions, and if these conditions can be ascertained, determining the cause becomes simple. In order to ascertain the conditions under which an intermittent malfunction occurs, first ask the customer for details about the driving conditions, weather conditions, frequency of occurrence and trouble symptoms, and then try to recreate the trouble symptoms. Next, ascertain whether the reason why the trouble symptom occurred under these conditions is due to vibration, temperature or some other factor. If vibration is thought to be the cause, carry out the following checks with the connectors and components to confirm whether the trouble symptom occurs. The objects to be checked are connectors and components which are indicated by inspection procedures or given as probable causes (which generates diagnosis codes or trouble symptoms).

Gently shake the connector up, down and to the left and right.

Gently shake the wiring harness up, down and to the left and right.

Gently rock each sensor and relay, etc. by hand.

Gently shake the wiring harness at suspensions and other moving parts.


HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS
CONTENTS OF TROUBLESHOOTING Troubleshooting of electronic control systems for which the MUT-II can be used follows the basic outline described below. Even in systems for which the MUT-II cannot be used, some of these systems still follow this outline.

1. STANDARD FLOW OF DIAGNOSTIC TROUBLESHOOTING Troubleshooting sections are based on the diagnostic flow as below. If the diagnostic flow is different from that given below, or if additional explanation is required, the details of such differences or additions will also be listed. Diagnosis method
	2. SYSTEM OPERATION AND SYMPTOM VERIFICATION TESTS If verification of the symptom(s) is difficult, procedures for checking operation and verifying symptoms are shown.
	3. DIAGNOSIS FUNCTION Details which are different from those in the "Diagnosis function " section are described.
	4. DIAGNOSIS CODE CHART Diagnostic trouble codes and diagnostic items are shown.
	5. DIAGNOSIS CODE PROCEDURES Indicates the inspection procedures corresponding to each diagnosis code (Refer to How to read inspection procedure ).
	6. TROUBLE SYMPTOM CHART If there are trouble symptoms even though the MUT-II does not find any diagnosis codes, Inspection procedures for each trouble symptom will be found by means of this chart.
	7. SYMPTOM PROCEDURES Indicates the inspection procedures corresponding to each symptoms classified in the Symptom Chart (Refer to How to read inspection procedure ).
	8. SERVICE DATA REFERENCE TABLE Inspection items and normal judgment values have been provided in this chart as reference information.
	9. CHECK AT ECU TERMINALS Terminal numbers for the ECU connectors, inspection items, and judgment values have been provided in this chart as reference information.
	10. INSPECTION PROCEDURE BY USING AN OSCILLOSCOPE When there are inspection procedures using an oscilloscope, these are described here.
	DIAGNOSIS FUNCTION
	HOW TO READ DIAGNOSIS CODE CAUTION Before connecting or disconnecting the MUT-II/III, turn the ignition switch to the "LOCK" (OFF) position. <Using the MUT-II>
	Connect the MUT-II to the diagnosis connector, and read the diagnosis code. <Using the MUT-III>
	Connect the MUT-III to the 16-pin diagnosis connector, and read the diagnosis code. NOTE: For details on how to use the MUT-III, refer to the "MUT-III operation manual." Ensure that the ignition switch is at the LOCK (OFF). Start up the personal computer. Connect MUT-III USB cable MB991827 to special tool Vehicle Communication Interface (V.C.I.) MB991824 and the personal computer. Connect MUT-III main harness B MB991911 to the V.C.I. Connect MUT-III main harness B to the diagnosis connector. Turn the V.C.I. power switch to the ON position. NOTE: When the V.C.I. is energized, the V.C.I. indicator lamp will be illuminated in a green colour. Start the MUT-III system on the PC and turn the ignition switch to the ON position. Read the diagnosis code. Disconnecting the MUT-III is the reverse of the connecting sequence, making sure that the ignition switch is at the LOCK (OFF). NOTE: The ABS warning lamp may flash when the ignition switch is turned ON with the MUT-II/III connected. This is because the diagnosis display function of the ABS warning lamp is activated by grounding the diagnosis connector terminal No.1, and is not detrimental in any way.

	ERASING DIAGNOSIS CODE (BY USING THE MUT-II/III) CAUTION Before connecting or disconnecting the MUT-II/III, turn the ignition switch to the "LOCK" (OFF) position.
	Connect the MUT-II/III to the diagnosis connector, and erase the diagnosis code. The procedure is the same as "HOW TO READ DIAGNOSIS CODE ".

	ERASING DIAGNOSIS CODE (BY USING NO MUT-II/III) CAUTION Some diagnosis codes can not be erased according to the procedure below. If you attempt to erase a diagnosis code, refer to an applicable GROUP. Turn the ignition switch to the "LOCK" (OFF) position. Disconnect the negative battery cable, wait for at least 10 minutes, and then reconnect it. Start the engine and let it run at idle for 10 minutes.
	INPUT SIGNAL CHECK (WHEN USING THE MUT-II/III) <SWS> CAUTION Before connecting or disconnecting the MUT-II/III, turn the ignition switch to the "LOCK" (OFF) position.
	Connect the MUT-II/III to the diagnosis connector, and erase the diagnosis code. If the MUT-II/III buzzer sounds once when each switch is operated (ON/OFF), the input signal for that switch circuit system is normal.

	INPUT SIGNAL CHECK (WHEN USING A VOLTMETER) <SWS>
	Use the special tool diagnosis code check harness (MB991529) to connect the ETACS terminal (terminal 9) and the earth terminals (terminals 4 and 5) of the diagnosis connector to the voltmeter. If the needle of the voltmeter flickers once when each switch is operated (ON/OFF), the input signal for that switch circuit system is normal.

HOW TO USE THE INSPECTION PROCEDURES The causes of many of the problems occurring in electric circuitry are generally the connectors, components, the ECU, the wiring harnesses between connectors, in that order. These inspection procedures follow this order. They first try to discover a problem with a connector or a defective component. HARNESS CHECK Check for an open or short circuit in the harness between the terminals which were faulty according to the connector measurements. Carry out this inspection while referring to the Electrical Wiring Manual. Here, "Check the wiring harness between the power supply and terminal xx" also includes checking for blown fuse. For inspection service points when there is a blown fuse, refer to "Inspection Service Points for a Blown Fuse ." MEASURES TO TAKE AFTER REPLACING THE ECU If the trouble symptoms have not disappeared even after replacing the ECU, repeat the inspection procedure from the beginning.
	CONNECTOR MEASUREMENT SERVICE POINTS Turn the ignition switch to the "LOCK" (OFF) position when connecting and disconnecting the connectors. Turn the ignition switch to "ON" when measuring, unless there are instructions to the contrary.
	IF INSPECTING WITH THE CONNECTOR CONNECTED <Waterproof Connectors>
	Be sure to use special tool harness connector (MD998459). Never insert a test probe from the harness side, as this will reduce the waterproof performance and result in corrosion.
	<Ordinary (non-waterproof) Connectors>
	Check by inserting the multi-meter test probe from the harness side. Note that if the connector (control unit, etc.) is too small to permit insertion of the test probe, it should not be forced; use the backprobing tool for this purpose.

	IF INSPECTING WITH THE CONNECTOR DISCONNECTED <When Inspecting a Female Pin>
	Use the special tool inspection harness (MB991219) (inspection harness for connector pin contact pressure in the harness set for inspection). The inspection harness for connector pin contact pressure should be used. the test bar should never be forcibly inserted, as it may cause a defective contact.
	<When Inspecting a Male Pin>
	CAUTION At this time, be careful not to short the connector pins with the test bars. To do so may damage the circuits inside the ECU. Touch the pin directly with the test bar.
	CONNECTOR INSPECTION SERVICE POINTS
	VISUAL INSPECTION
	Connector is disconnected or improperly connected Connector pins are pulled out Due to harness tension at terminal section Low contact pressure between male and female terminals Low connection pressure due to rusted terminals or foreign matter lodged in terminals

	CONNECTOR PIN INSPECTION
	If the connector pin stopper is damaged, the terminal connections (male and female pins) will not be perfect even if the connector body is connected, and the pins may pull out of the reverse side of the connector. Therefore, gently pull the harnesses one by one to make sure that no pins pull out of the connector.

	CONNECTOR ENGAGEMENT INSPECTION
	Use the special tool inspection harness (MB991219) (connector pin connection pressure inspection harness of the inspection harness set) to inspect the engagement of the male pins and females pins. (Pin drawing force: 1 N or more)
	INSPECTION SERVICE POINTS FOR A BLOWN FUSE
	Remove the blown fuse and measure the resistance between the load side of the blown fuse and the earth. Close the switches of all circuits which are connected to this fuse. If the resistance is almost 0 Ω at this time, there is a short somewhere between these switches and the load. If the resistance is not 0 Ω, there is no short at the present time, but a momentary short has probably caused the fuse to blow. The main causes of a short circuit are the following. Harness being clamped by the vehicle body Damage to the outer casing of the harness due to wear or heat Water getting into the connector or circuitry Human error (mistakenly shorting a circuit, etc.)
	HOW TO COPE WITH INTERMITTENT MALFUNCTIONS NOTE: If determining the cause is difficult, the flight recorder function of the MUT-II can also be used.
	Intermittent malfunctions often occur under certain conditions, and if these conditions can be ascertained, determining the cause becomes simple. In order to ascertain the conditions under which an intermittent malfunction occurs, first ask the customer for details about the driving conditions, weather conditions, frequency of occurrence and trouble symptoms, and then try to recreate the trouble symptoms. Next, ascertain whether the reason why the trouble symptom occurred under these conditions is due to vibration, temperature or some other factor. If vibration is thought to be the cause, carry out the following checks with the connectors and components to confirm whether the trouble symptom occurs. The objects to be checked are connectors and components which are indicated by inspection procedures or given as probable causes (which generates diagnosis codes or trouble symptoms). Gently shake the connector up, down and to the left and right. Gently shake the wiring harness up, down and to the left and right. Gently rock each sensor and relay, etc. by hand. Gently shake the wiring harness at suspensions and other moving parts.