INSPECTION PROCEDURE 1: Communication with MUT-II/III is not possible. (Communication is not possible with SRS).

OPERATION

The SRS-ECU is powered from the ignition switch (IG1).

The SRS-ECU power is supplied from two circuits. Even if one circuit is shut off, the air bag can inflate.

The SRS system diagnosis can be done by connecting MUT-II/III to the diagnosis connector.

COMMENTS ON TROUBLE SYMPTOM

If communication is not possible with the SRS only, the cause is probably an open circuit in the on-board diagnostic output circuit of the SRS or in the power circuit (including earth circuit).

PROBABLE CAUSES

Damaged wiring harnesses or connectors

Malfunction of the SRS-ECU

Incorrect MUT-II (MUT-II) ROM pack

DIAGNOSIS PROCEDURE

STEP 1. Check that the MUT-II/III can communicate with the other systems.

Q: Can the MUT-II/III communicate with the other systems?

YES: Go to Step 2

.
NO: <4G63> Refer to GROUP 13A - Troubleshooting

<4G64> Refer to GROUP 13B - Troubleshooting

<4G69> Refer to GROUP 13C - Troubleshooting

STEP 2. Check the communication line between the SRS-ECU and the MUT-II/III.

Disconnect SRS-ECU connector C-115 and diagnosis connector C-24, and measure at the wiring harness side.

CAUTION

Do not insert a test probe into the terminal from of the SRS-ECU connector C-115 its front side directly as the connector contact pressure may be weakened.

Check for continuity between the following terminals.

SRS-ECU connector C-115 (terminal No.20) and diagnosis connector C-24 (terminal No.7)

OK: Less than 2 Ω

Q: Is the check results normal?

YES: Go to Step 3

.
NO: Go to Step 5

STEP 3. Check the earth circuit to the SRS-ECU.

Disconnect SRS-ECU connector C-115, and measure at the wiring harness side.

CAUTION

Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.

Check for continuity between terminal 7 and body earth.

OK: Less than 2 Ω

Q: Is the check result normal?

YES: Go to Step 4

.
NO: Go to Step 6

STEP 4. Check the power supply circuit to the SRS-ECU.

Disconnect SRS-ECU connector C-115, and measure at the wiring harness side.

Connect the negative battery terminal.

Turn the ignition switch to the "ON" position.

CAUTION

Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.

Measure the voltage between terminals 13, 16 and body earth.

OK: 9 V or more

Q: Is the check result normal?

YES: Recheck the trouble symptom. If it is not solved, replace the SRS-ECU (Refer to

). Then go to Step 8

.
NO: Go to Step 7

STEP 5. Check the harness wires between SRS-ECU connector C-115 (terminal No.20) and diagnosis connector C-24 (terminal No.7).

NOTE: After inspecting intermediate connector C-02, inspect the wiring harness. If the intermediate connector C-02 is damaged, repair or replace it. Then go to Step 8

Q: Are the harness wires between SRS-ECU connector C-115 (terminal No.20) and diagnosis connector C-24 (terminal No.7) in good condition?

YES: Go to step 8

.
NO: Repair the harness wires between SRS-ECU connector C-115 and diagnosis connector C-24. Then go to Step 8

STEP 6. Check the harness wire between SRS-ECU connector C-115 (terminal No.7) and earth.

Q: Is the harness wire between SRS-ECU connector C-115 (terminal No.7) and earth in good condition?

YES: Go to Step 8

.
NO: Repair the harness wire between SRS-ECU connector C-115 and earth. Then go to Step 8

STEP 7. Check the harness wires between SRS-ECU connector C-115 (terminal No.13 and 16) and ignition switch connector C-303 (terminal No.2).

NOTE: After inspecting intermediate connector C-203 and C-205, inspect the wiring harness. If the intermediate connector C-203 or C-205 is damaged, repair or replace it. Then go to Step 8

Q: Are the harness wires between SRS-ECU connector C-115 (terminal No.13 and 16) and ignition switch connector C-303 (terminal No.2) in good condition?

YES: Go to Step 8

.
NO: Repair the harness wires between SRS-ECU connector C-115 and ignition switch connector C-303. Then go to Step 8

STEP 8. Retest the system.

Q: Does the MUT-II/III communicate normally with the SRS system?

YES: The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected). Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points

.
NO: There is no action to be taken.


INSPECTION PROCEDURE 1: Communication with MUT-II/III is not possible. (Communication is not possible with SRS).

OPERATION The SRS-ECU is powered from the ignition switch (IG1). The SRS-ECU power is supplied from two circuits. Even if one circuit is shut off, the air bag can inflate. The SRS system diagnosis can be done by connecting MUT-II/III to the diagnosis connector.
COMMENTS ON TROUBLE SYMPTOM If communication is not possible with the SRS only, the cause is probably an open circuit in the on-board diagnostic output circuit of the SRS or in the power circuit (including earth circuit).
PROBABLE CAUSES Damaged wiring harnesses or connectors Malfunction of the SRS-ECU Incorrect MUT-II (MUT-II) ROM pack

	DIAGNOSIS PROCEDURE

	STEP 1. Check that the MUT-II/III can communicate with the other systems. Q: Can the MUT-II/III communicate with the other systems? YES: Go to Step 2 . NO: <4G63> Refer to GROUP 13A - Troubleshooting <4G64> Refer to GROUP 13B - Troubleshooting <4G69> Refer to GROUP 13C - Troubleshooting .
	STEP 2. Check the communication line between the SRS-ECU and the MUT-II/III. Disconnect SRS-ECU connector C-115 and diagnosis connector C-24, and measure at the wiring harness side.
	CAUTION Do not insert a test probe into the terminal from of the SRS-ECU connector C-115 its front side directly as the connector contact pressure may be weakened. Check for continuity between the following terminals. SRS-ECU connector C-115 (terminal No.20) and diagnosis connector C-24 (terminal No.7) OK: Less than 2 Ω Q: Is the check results normal? YES: Go to Step 3. NO: Go to Step 5.
	STEP 3. Check the earth circuit to the SRS-ECU. Disconnect SRS-ECU connector C-115, and measure at the wiring harness side.
	CAUTION Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened. Check for continuity between terminal 7 and body earth. OK: Less than 2 Ω Q: Is the check result normal? YES: Go to Step 4. NO: Go to Step 6.
	STEP 4. Check the power supply circuit to the SRS-ECU. Disconnect SRS-ECU connector C-115, and measure at the wiring harness side. Connect the negative battery terminal. Turn the ignition switch to the "ON" position.
	CAUTION Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened. Measure the voltage between terminals 13, 16 and body earth. OK: 9 V or more Q: Is the check result normal? YES: Recheck the trouble symptom. If it is not solved, replace the SRS-ECU (Refer to ). Then go to Step 8. NO: Go to Step 7.
	STEP 5. Check the harness wires between SRS-ECU connector C-115 (terminal No.20) and diagnosis connector C-24 (terminal No.7). NOTE: After inspecting intermediate connector C-02, inspect the wiring harness. If the intermediate connector C-02 is damaged, repair or replace it. Then go to Step 8 . Q: Are the harness wires between SRS-ECU connector C-115 (terminal No.20) and diagnosis connector C-24 (terminal No.7) in good condition? YES: Go to step 8. NO: Repair the harness wires between SRS-ECU connector C-115 and diagnosis connector C-24. Then go to Step 8.
	STEP 6. Check the harness wire between SRS-ECU connector C-115 (terminal No.7) and earth. Q: Is the harness wire between SRS-ECU connector C-115 (terminal No.7) and earth in good condition? YES: Go to Step 8 . NO: Repair the harness wire between SRS-ECU connector C-115 and earth. Then go to Step 8.
	STEP 7. Check the harness wires between SRS-ECU connector C-115 (terminal No.13 and 16) and ignition switch connector C-303 (terminal No.2). NOTE: After inspecting intermediate connector C-203 and C-205, inspect the wiring harness. If the intermediate connector C-203 or C-205 is damaged, repair or replace it. Then go to Step 8 . Q: Are the harness wires between SRS-ECU connector C-115 (terminal No.13 and 16) and ignition switch connector C-303 (terminal No.2) in good condition? YES: Go to Step 8. NO: Repair the harness wires between SRS-ECU connector C-115 and ignition switch connector C-303. Then go to Step 8.
	STEP 8. Retest the system. Q: Does the MUT-II/III communicate normally with the SRS system? YES: The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected). Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points . NO: There is no action to be taken.