INSPECTION PROCEDURE 1: Communication with M.U.T.-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 M.U.T.-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 diagnosis 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

DIAGNOSIS PROCEDURE

STEP 1. Resistance measurement between SRS-ECU connector C-147 (terminal No.20) and diagnosis connector C-126 (terminal No.7).

(1)Disconnect SRS-ECU connector C-126 and diagnosis connector C-126, and measure at the wiring harness side.

(2)

caution

Do not insert a test probe into the terminal from of the SRS-ECU connector C-147 its front side directly as the connector contact pressure may be weakened.

Resistance measurement between the following terminals.

SRS-ECU connector C-147 (terminal No.20) and diagnosis connector C-126 (terminal No.7)

OK: Less than 2 Ω

Q. Is the check results normal?

Go to Step 2.

Go to Step 4.

STEP 2. Resistance measurement the earth circuit to the SRS-ECU connector C-147.

(1)Disconnect SRS-ECU connector C-147 and measure at the wiring harness side.

(2)

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 19 and body earth.
OK: Less than 2 Ω

Q. Is the check result normal?

Go to Step 3.

Check the harness wire for open circuit between SRS-ECU connector C-147 (terminal No.19) and earth, and repair if necessary.

STEP 3. Voltage measurement the power supply circuit to the SRS-ECU connector C-147.

(1)Disconnect SRS-ECU connector C-147 and measure at the wiring harness side.
(2)Connect the negative battery terminal.
(3)Turn the ignition switch to the "ON" position.

(4)

caution

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

Voltage measurement between terminals 13, 16 and body earth.
OK: 9 V or more

Q. Is the check result normal?

Go to Step 6.

Go to Step 5.

STEP 4. Check the harness wires between SRS-ECU connector C-147 and diagnosis connector C-126.

note

Prior to the wiring harness inspection, check junction connector C-01, and repair if necessary.

Q. Is the check result normal?

An intermittent malfunction is suspected (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points

Check the harness wires for open or short circuit between SRS-ECU connector C-147 (terminal No.20) and diagnosis connector C-126 (terminal No.7) and repair if necessary.

STEP 5. Check the connectors between SRS-ECU connector C-147 and ignition switch connector C-307.

note

Prior to the wiring harness inspection, check junction block connectors C-202 and C-205, and repair if necessary.

Q. Is the check result normal?

An intermittent malfunction is suspected (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points

Check the harness wires for open or short circuit between SRS-ECU connector C-147 (terminal No.20) and ignition switch connector C-307, and repair if necessary.

STEP 6. Retest the system.

Q. Does the M.U.T.-III communicate normally with the SRS system?

	An intermittent malfunction is suspected (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points ).

	Replace the SRS-ECU (Refer to ).