Diagnosis code 71: Side Air bag Module (RH) (Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit)

OPERATION

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

The ignition signal is input to the side air bag module to inflate the side air bag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal resistance between the input terminals of the side air bag module (RH) (squib).

PROBABLE CAUSES

Improper engaged connector or defective short spring*

Short between the side air bag module (RH) (squib) circuit terminals

Damaged connector(s)

Malfunction of the SRS-ECU

NOTE: *: The squib circuit connectors integrate a "short" spring (which prevents the air bag from deploying unintentionally due to static electricity by shorting the positive wire to the earth wire in the squib circuit when the connectors are disconnected). Therefore, if connector C-114 or D-40 is damaged or improperly engaged, the short spring may not be released when the connector is connected.

DIAGNOSIS PROCEDURE

STEP 1. MUT-II/III diagnosis code

CAUTION

To prevent damage to MUT-II/III, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting MUT-II/III.

Turn the ignition switch to the "ON" position.

Check if the diagnosis code is set.

Turn the ignition switch to the "LOOK" (OFF) position.

Q: Is diagnosis code 34 set?

YES: Go to Step 2

.
NO: Go to Step 3

STEP 2. Connector check: SRS-ECU connector C-114

Q: Is the connector correctly engaged?

YES: Go to Step 3

.
NO: Engage the connector correctly. Then go to Step 7

STEP 3. Connector check: SRS-ECU connector C-114 and side air bag module (RH) connector D-40 (Check whether the diagnosis code is reset).

Disconnect the negative battery terminal.

Disconnect connectors C-114 and D-40, and then reconnect them.

Connect the negative battery terminal.

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

Q: Is diagnosis code 71 out put?

YES: Go to Step 4

.
NO: The procedure is complete. It is assumed that diagnosis code 71 set as connector C-114 or D-40 was engaged improperly.

STEP 4. Check the side air bag module (RH) (Check whether the diagnosis code is reset).

Disconnect the negative battery terminal.

Disconnect the side air bag module (RH) connector D-40.

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.

Insert special tool (MB991866) into the D-40 harness side connector by backprobing.

Connect the negative battery terminal.

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

Q: Is diagnosis code 71 set?

YES: Go to Step 5

.
NO: Replace the seat back assembly of the front seat (RH) (Refer to GROUP 52A - Front Seat

). Then go to Step 7

STEP 5. Check the side air bag module (RH) circuit at the SRS-ECU connector C-114.

Disconnect SRS-ECU connector C-114.

DANGER

To prevents the air bag from deploying unintentionally, disconnect the side air bag module (RH) connector D-40 to short the squib circuit.

Disconnect side air bag module connector D-40.

CAUTION

Insert an insulator such as a cable tie to a depth of 4mm or more, otherwise the short spring will not be released.

Insert a cable tie [3 mm wide, 0.5 mm thick] between terminals 23, 24 and the short spring to release the short spring.

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 C-114 harness side connector terminals 23 and 24.

OK: Open circuit

Q: Is the check result normal?

YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 71 sets, replace the SRS-ECU (Refer to

). Then go to Step 7

.
NO: Go to Step 6

STEP 6. Check the harness wires for short circuit between SRS-ECU connector C-114 (terminal No.23 and 24) and side air bag module (RH) connector D-40 (terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector C-114 (terminal No.23 and 24) and side air bag module (RH) connector D-40 (terminal No.1 and 2) in good condition?

YES: Go to Step 7

.
NO: Repair the harness wires between SRS-ECU connector C-114 and side air bag module (RH) connector D-40. Then go to Step 7

STEP 7. Check whether the diagnosis code is reset.

Q: Is diagnosis code 71 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 71: Side Air bag Module (RH) (Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit)

OPERATION The SRS-ECU judges how severe a collision is by detecting signals from the left and right side impact sensors. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the side air bag safing G-sensor is on, the SRS side air bag will inflate. The ignition signal is input to the side air bag module to inflate the side air bag.
DIAGNOSIS CODE SET CONDITIONS This diagnosis code is set if there is abnormal resistance between the input terminals of the side air bag module (RH) (squib).
PROBABLE CAUSES Improper engaged connector or defective short spring* Short between the side air bag module (RH) (squib) circuit terminals Damaged connector(s) Malfunction of the SRS-ECU
NOTE: *: The squib circuit connectors integrate a "short" spring (which prevents the air bag from deploying unintentionally due to static electricity by shorting the positive wire to the earth wire in the squib circuit when the connectors are disconnected). Therefore, if connector C-114 or D-40 is damaged or improperly engaged, the short spring may not be released when the connector is connected.
	DIAGNOSIS PROCEDURE

	STEP 1. MUT-II/III diagnosis code CAUTION To prevent damage to MUT-II/III, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting MUT-II/III. Turn the ignition switch to the "ON" position. Check if the diagnosis code is set. Turn the ignition switch to the "LOOK" (OFF) position. Q: Is diagnosis code 34 set? YES: Go to Step 2 . NO: Go to Step 3.
	STEP 2. Connector check: SRS-ECU connector C-114 Q: Is the connector correctly engaged? YES: Go to Step 3 . NO: Engage the connector correctly. Then go to Step 7.
	STEP 3. Connector check: SRS-ECU connector C-114 and side air bag module (RH) connector D-40 (Check whether the diagnosis code is reset). Disconnect the negative battery terminal. Disconnect connectors C-114 and D-40, and then reconnect them. Connect the negative battery terminal. Erase the diagnosis code memory, and check the diagnosis code. Q: Is diagnosis code 71 out put? YES: Go to Step 4 . NO: The procedure is complete. It is assumed that diagnosis code 71 set as connector C-114 or D-40 was engaged improperly.
	STEP 4. Check the side air bag module (RH) (Check whether the diagnosis code is reset). Disconnect the negative battery terminal. Disconnect the side air bag module (RH) connector D-40.
	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. Insert special tool (MB991866) into the D-40 harness side connector by backprobing. Connect the negative battery terminal. Erase the diagnosis code memory, and check the diagnosis code. Q: Is diagnosis code 71 set? YES: Go to Step 5. NO: Replace the seat back assembly of the front seat (RH) (Refer to GROUP 52A - Front Seat ). Then go to Step 7.
	STEP 5. Check the side air bag module (RH) circuit at the SRS-ECU connector C-114. Disconnect SRS-ECU connector C-114. DANGER To prevents the air bag from deploying unintentionally, disconnect the side air bag module (RH) connector D-40 to short the squib circuit. Disconnect side air bag module connector D-40.
	CAUTION Insert an insulator such as a cable tie to a depth of 4mm or more, otherwise the short spring will not be released. Insert a cable tie [3 mm wide, 0.5 mm thick] between terminals 23, 24 and the short spring to release the short spring. 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 C-114 harness side connector terminals 23 and 24. OK: Open circuit Q: Is the check result normal? YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 71 sets, replace the SRS-ECU (Refer to ). Then go to Step 7 . NO: Go to Step 6.
	STEP 6. Check the harness wires for short circuit between SRS-ECU connector C-114 (terminal No.23 and 24) and side air bag module (RH) connector D-40 (terminal No.1 and 2). Q: Are the harness wires between SRS-ECU connector C-114 (terminal No.23 and 24) and side air bag module (RH) connector D-40 (terminal No.1 and 2) in good condition? YES: Go to Step 7 . NO: Repair the harness wires between SRS-ECU connector C-114 and side air bag module (RH) connector D-40. Then go to Step 7.
	STEP 7. Check whether the diagnosis code is reset. Q: Is diagnosis code 71 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 .