Code No.66: Driver’s seat belt pre-tensioner (squib) system (short-circuited to the power supply)




OPERATION


The SRS-ECU judges how severe a collision is by detecting signals from the front impact sensors and the front air bag analog G-sensor. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the front air bag safing G-sensor is on, the pre-tensioner will deploy.

DIAGNOSIS CODE SET CONDITIONS


This diagnosis code is set if the driver’s seat belt pre-tensioner wire(s) are short-circuited to the power supply.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Check the diagnosis code by connecting a dummy resistor (M.U.T.-III diagnosis code).
(1)Disconnect the negative battery terminal.

(2)Disconnect intermediate connector C-148 (pre-tensioner harness and instrument panel harness connection).

(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
(4)
caution Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
Connect special tool (MB991866) to the C-148 harness side connector by backprobing.
(5)Connect the negative battery terminal.
(6)Erase diagnosis code memory, and check the diagnosis code.

Q. Is diagnosis code 66 set?

Go to Step 2.

Go to Step 3.

STEP 2. Voltage measurement at the SRS-ECU connector C-147.
(1)Disconnect the negative battery terminal.

(2)Disconnect SRS-ECU connector C-147.
(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 C-147 harness side connector terminals 5, 6 and body earth.
OK: 0 V

Q. Is the check result normal?

Go to Step 4.

Repair the harness wire between SRS-ECU connector C-147 (terminal No. 5 and 6) and harness side connector C-148 (terminal No. 1 and 2).

STEP 3. Voltage measurement at the pre-tensioner side connector C-148.

(1)Disconnect the negative battery terminal.
(2)Disconnect intermediate connector C-148 (pre-tensioner harness and instrument panel harness connection).
(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 C-148 pre-tensioner side connector terminals1, 2 and body earth.
OK: 0 V

Q. Is the check result normal?

Replace the driver’s seat belt pre-tensioner (Refer to).

Repair the harness wire between pre-tensioner side connector C-148 (terminal No. 1 and 2) and driver’s seat belt pre-tensioner connector D-32 (terminal No. 1 and 2).

STEP 4. Check whether the diagnosis code is reset.

Q. Is diagnosis code 66 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points ).