B1490
DTC B1410: Passenger's
(Front) Air Bag Module (1st squib) System (Short Circuit Between Squib Circuit Terminals)
DTC B1490: Passenger's (Front) Air Bag Module (2nd squib) System (Short Circuit Between Squib Circuit Terminals)
CAUTION:
- If DTC B1410 [1st squib] or B1490 [2nd squib] is set in the SRS-ECU, always diagnose the CAN main bus line.
- When DTC B1410 is set in the following diagnosis, check the 1st squib circuit. When DTC B1490 is set, check the 2nd squib circuit.
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 sends 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 to inflate the air bag.
DTC SET CONDITIONS
This DTC is set if there is abnormal resistance between the input terminals of the passenger's side air bag module (squib).
TROUBLESHOOTING HINTS
- Improper engaged connector or defective short spring*
- Short circuit between the passenger's air bag module (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 ground wire in the squib circuit when the connectors are disconnected). Therefore, if connector C-114 or C-126 is damaged or improperly engaged, the short spring may not be released when the connector is connected.
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
(1)
CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to "How to connect the scan tool Reading and Clearing Diagnostic Trouble Codes."
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the CAN bus line found to be normal?
YES Go to Step 2.
NO Repair the CAN bus line CAN Bus Diagnostics Chart).
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1)Erase the DTC.
(2)Turn the ignition switch to the "ON" position.
(3)Check if the DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the DTC set?
YES Go to Step 3.
NO There is an intermittent malfunction such as poor engaged connector(s) or open circuit How to Cope With Intermittent Malfunctions).
STEP 3. Check SRS-ECU connector C-126 and passenger's (front) air bag module connector C-114.
(1)Disconnect the negative battery terminal.
(2)While pushing the part "A" indicated in the figure of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever. After disconnecting the C-126 SRS-ECU connector, connect it again.
(3)After disconnecting harness side connector C-114 while sliding the outer housing of the connector to the direction of the arrow, connect the connector again.
(4)Connect the negative battery terminal.
(5)Erase the diagnostic trouble code memory, and check the diagnostic trouble code.
Q. Is DTC B1410 [1st squib] or B1490 [2nd squib] set?
YES Go to Step 4.
NO The procedure is complete. It is assumed that DTC B1410 [1st squib] or B1490 [2nd squib] set as connector C-126 or C-114 was engaged improperly.
STEP 4. Check the passenger's (front) air bag module.
(1)Disconnect the negative battery terminal.
(2)Slide the outer housing of harness side connector in the arrow direction shown, and disconnect the C-114 harness side connector.
(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
(4)
CAUTION:
Do not insert a probe into the terminal from its front side directly as the connector contact pressure may be weakened.
Insert special tool MB991866 into the harness side connector C-114 (terminal No.1 and 2 [1st squib] or terminal No.3 and 4 [2nd squib]) by backprobing.
(5)Connect the negative battery terminal.
(6)
CAUTION:
Always DTC B1491 is set when checking DTC B1410. This is because the second side terminal is isolated when checking it. DTC B1491 is set but this is not a fault. In addition, always DTC B411 is set when checking DTC B1490 because the first side terminal is isolated.
Erase the diagnostic trouble code memory, and check the diagnostic trouble code.
Q. Is the checked DTC set?
YES Go to Step 5.
NO Replace the passenger's air bag module (Refer to Removal and Installation).
Then go to Step 7.
STEP 5. Check the passenger's (front) air bag module circuit at SRS-ECU connector C-126.
(1)Disconnect the negative battery terminal.
(2)While pushing the part "A" indicated in the figure of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-126 SRS-ECU connector.
(3)DANGER:
To prevent the air bag from deploying unintentionally, disconnect the passenger's (front) air bag module connector C-114 to short the squib circuit.
(4)Slide the outer housing of harness side connector in the arrow direction shown, and disconnect the C-114 harness side connector.
(5)
CAUTION:
Insert an insulator such as a cable tie to a depth of 4 mm (0.16 inch) or more, otherwise the short spring will not be released.
Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 7 and 8 [1st squib] or 9 and 10 [2nd squib], and the short spring to release the short spring.
(6)Check for continuity between C-126 harness side connector terminals 7 and 8 [1st squib] or 9 and 10 [2nd squib].
It should be open circuit.
Q. Is it open circuit?
YES Erase the diagnostic trouble code memory, and check the diagnostic trouble code.
If DTC B1410 [1st squib] or B1490 [2nd squib] set, replace the SRS-ECU. (Refer to Service and Repair). Go to Step 7.
NO Go to Step 6.
STEP 6. Check the harness for short circuit between the harness wire and wire.
- SRS-ECU connector C-126 (terminal No.7 and 8) and passenger's (front) air bag module connector C-114 (terminal No.2 and 1) [1st squib].
- SRS-ECU connector C-126 (terminal No.9 and 10) and passenger's (front) air bag module connector C-114 (terminal No.4 and 3) [2nd squib].
Q. Is the check result normal?
YES Go to Step 7.
NO Repair the harness wires between SRS-ECU connector C-126 and passenger's
(front) air bag module connector C-114. Then go to Step 7.
STEP 7. Check for diagnostic trouble code.
Check again if the DTC is set.
(1)Erase the DTC.
(2)Turn the ignition switch to the "ON" position.
(3)Check if the DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is DTC B1410 [1st squib] or B1490 [2nd squib] set?
YES Return to Step 1.
NO The procedure is complete.