Diagnosis code 25: Passenger’s (Front) Air Bag Module (Squib) System Fault 2 (Open in the Squib Circuit)

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 SRS air bag will inflate.

The ignition signal is input to the air bag module via the clock spring to inflate the air bag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal resistance between the input terminals of the passenger’s air bag module (squib). However, if no diagnosis code resets, the SRS warning lamp will be switched off (diagnosis code will be retained).

PROBABLE CAUSES

Open circuit in the passenger's air bag module (squib) circuit

Improper connector contact

Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the passenger's air bag module (Check whether the diagnosis code is reset).

Disconnect the negative battery terminal.

Unclip passenger’s air bag module connector C-09.

Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).

CAUTION

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

Disconnect the passenger's air bag module connector C-09, and insert special tool (MB991866) into the harness side connector by backprobing.

Connect the negative battery terminal.

Erase the diagnosis code memory, and check the diagnosis code.

Q: Is diagnosis code 25 set?

YES: Go to Step 2

.
NO: Replace the passenger's air bag module (Refer to

). Then go to Step 3

STEP 2. Check the harness for open circuit between SRS-ECU connector C-115 (terminal No.9 and 10) and the passenger's air bag module connector C-09 (terminal No.1 and 2).

Unclip passenger’s air bag module connector C-09.

Disconnect SRS-ECU connector C-115 and passenger's air bag module connector C-09.

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 the following terminals.

SRS-ECU connector C-115 (terminal No.9) and the passenger’s air bag module connector C-09 (terminal No.1)

SRS-ECU connector C-115 (terminal No.10) and the passenger’s air bag module connector C-09 (terminal No.2)

OK: Less than 2 Ω

Q: Are the check results normal?

YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 25 sets, replace the SRS-ECU (Refer to

). Then go to Step 3

.
NO: Repair the harness wires between SRS-ECU connector C-115 and passenger’s air bag module connector C-09. Then go to Step 3

STEP 3. Check whether the diagnosis code is reset.

Q: Is diagnosis code 25 set?

YES: Return to Step 1

.
NO: 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


Diagnosis code 25: Passenger’s (Front) Air Bag Module (Squib) System Fault 2 (Open in the Squib Circuit)

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 SRS air bag will inflate. The ignition signal is input to the air bag module via the clock spring to inflate the air bag.
DIAGNOSIS CODE SET CONDITIONS This diagnosis code is set if there is abnormal resistance between the input terminals of the passenger’s air bag module (squib). However, if no diagnosis code resets, the SRS warning lamp will be switched off (diagnosis code will be retained).
PROBABLE CAUSES Open circuit in the passenger's air bag module (squib) circuit Improper connector contact Malfunction of the SRS-ECU
	DIAGNOSIS PROCEDURE

	STEP 1. Check the passenger's air bag module (Check whether the diagnosis code is reset). Disconnect the negative battery terminal. Unclip passenger’s air bag module connector C-09.
	Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866). CAUTION Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened. Disconnect the passenger's air bag module connector C-09, and insert special tool (MB991866) into the harness side connector by backprobing. Connect the negative battery terminal. Erase the diagnosis code memory, and check the diagnosis code. Q: Is diagnosis code 25 set? YES: Go to Step 2. NO: Replace the passenger's air bag module (Refer to ). Then go to Step 3.
	STEP 2. Check the harness for open circuit between SRS-ECU connector C-115 (terminal No.9 and 10) and the passenger's air bag module connector C-09 (terminal No.1 and 2). Unclip passenger’s air bag module connector C-09. Disconnect SRS-ECU connector C-115 and passenger's air bag module connector C-09.
	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 the following terminals. SRS-ECU connector C-115 (terminal No.9) and the passenger’s air bag module connector C-09 (terminal No.1) SRS-ECU connector C-115 (terminal No.10) and the passenger’s air bag module connector C-09 (terminal No.2) OK: Less than 2 Ω Q: Are the check results normal? YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 25 sets, replace the SRS-ECU (Refer to ). Then go to Step 3 . NO: Repair the harness wires between SRS-ECU connector C-115 and passenger’s air bag module connector C-09. Then go to Step 3.
	STEP 3. Check whether the diagnosis code is reset. Q: Is diagnosis code 25 set? YES: Return to Step 1 . NO: 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 .