Diagnosis code 27: Driver’s Seat Belt Pre-Tensioner (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 pre-tensioner will deploy.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal resistance between the input terminals of the driver's seat belt pre-tensioner (squib).

PROBABLE CAUSES

Improper connector contact

Open circuit in the driver's seat belt pre-tensioner (squib) circuit

Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the driver's seat belt pre-tensioner (Check whether the diagnosis code is reset).

Disconnect the negative battery terminal.

Disconnect driver's seat belt pre-tensioner connector D-29 <2400> or D-43 <2000>. Use a flat-tipped screwdriver to pull out the locking button at the harness side connector, and then disconnect the connector.

Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884).

Connect special tool MB991884 to the D-29 <2400> or D-43 <2000> harness side connector.

Connect the negative battery terminal.

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

Q: Is diagnosis code 27 set?

YES: Go to Step 2

.
NO: Replace the driver's seat belt pre-tensioner (Refer to

). Then go to Step 3

STEP 2. Check the harness for open circuit between SRS-ECU connector C-114 (terminal No.29 and 30 <except 2400 (RH drive vehicles)>, No.27 and 28 <2400 (RH drive vehicles)>) and the driver's seat belt pre-tensioner D-29 <2400> or D-43 <2000> (terminal No.1 and 2).

Disconnect SRS-ECU connector C-114 and driver's seat belt pre-tensioner connector D-29 <2400> or D-43 <2000>, and measure at the wiring harness side. For connector D-29 <2400> or D-43 <2000>, use a flat-tipped screwdriver to pull out the locking button at the harness side connector, and then disconnect the connector.

Connect D-29 <2400> or D-43 <2000> harness side connector to special tool resistor harness (MB991884).

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-114 (terminal No.29) and special tool (terminal No.1)

SRS-ECU connector C-114 (terminal No.30) and special tool (terminal No.2)

<2400 (RH drive vehicles)>

SRS-ECU connector C-114 (terminal No.27) and special tool (terminal No.2)

SRS-ECU connector C-114 (terminal No.28) and special tool (terminal No.1)

OK: Less than 2 Ω

Q: Are the check results normal?

YES: Erase the diagnosis code memory, and recheck if any diagnosis code sets. If diagnosis code 27 sets, replace the SRS-ECU (Refer to

). Then go to Step 3

.
NO: Repair harness wires between SRS-ECU connector C-114 and driver’s seat belt pre-tensioner connector D-29 <2400> or D-43 <2000>. Then go to Step 3

STEP 3. Check whether the diagnosis code is reset.

Q: Is diagnosis code No.27 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 27: Driver’s Seat Belt Pre-Tensioner (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 pre-tensioner will deploy.
DIAGNOSIS CODE SET CONDITIONS This diagnosis code is set if there is abnormal resistance between the input terminals of the driver's seat belt pre-tensioner (squib).
PROBABLE CAUSES Improper connector contact Open circuit in the driver's seat belt pre-tensioner (squib) circuit Malfunction of the SRS-ECU
	DIAGNOSIS PROCEDURE

	STEP 1. Check the driver's seat belt pre-tensioner (Check whether the diagnosis code is reset). Disconnect the negative battery terminal.
	Disconnect driver's seat belt pre-tensioner connector D-29 <2400> or D-43 <2000>. Use a flat-tipped screwdriver to pull out the locking button at the harness side connector, and then disconnect the connector.
	Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884). Connect special tool MB991884 to the D-29 <2400> or D-43 <2000> harness side connector. Connect the negative battery terminal. Erase diagnosis code memory, and then check the diagnosis code. Q: Is diagnosis code 27 set? YES: Go to Step 2. NO: Replace the driver's seat belt pre-tensioner (Refer to ). Then go to Step 3.
	STEP 2. Check the harness for open circuit between SRS-ECU connector C-114 (terminal No.29 and 30 <except 2400 (RH drive vehicles)>, No.27 and 28 <2400 (RH drive vehicles)>) and the driver's seat belt pre-tensioner D-29 <2400> or D-43 <2000> (terminal No.1 and 2).
	Disconnect SRS-ECU connector C-114 and driver's seat belt pre-tensioner connector D-29 <2400> or D-43 <2000>, and measure at the wiring harness side. For connector D-29 <2400> or D-43 <2000>, use a flat-tipped screwdriver to pull out the locking button at the harness side connector, and then disconnect the connector. Connect D-29 <2400> or D-43 <2000> harness side connector to special tool resistor harness (MB991884).
	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. <Except 2400 (RH drive vehicles)> SRS-ECU connector C-114 (terminal No.29) and special tool (terminal No.1) SRS-ECU connector C-114 (terminal No.30) and special tool (terminal No.2) <2400 (RH drive vehicles)> SRS-ECU connector C-114 (terminal No.27) and special tool (terminal No.2) SRS-ECU connector C-114 (terminal No.28) and special tool (terminal No.1) OK: Less than 2 Ω Q: Are the check results normal? YES: Erase the diagnosis code memory, and recheck if any diagnosis code sets. If diagnosis code 27 sets, replace the SRS-ECU (Refer to ). Then go to Step 3. NO: Repair harness wires between SRS-ECU connector C-114 and driver’s seat belt pre-tensioner connector D-29 <2400> or D-43 <2000>. Then go to Step 3.
	STEP 3. Check whether the diagnosis code is reset. Q: Is diagnosis code No.27 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 .