B1452
DTC B1452: Curtain Air Bag Module (LH) (Squib) System (Shorted to Squib Circuit Ground)
CAUTION:
If DTC B1452 is set in the SRS-ECU, always diagnose the CAN main bus line.
CIRCUIT OPERATION
- The SRS-ECU judges how severe a collision is by detecting signals from the side impact sensors installed on the lower side of the center pillar. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the side collision safing G-sensor is on, the SRS air bag will inflate.
- The ignition signal is input to the curtain air bag module (LH) to inflate the curtain air bag.
DTC SET CONDITIONS
This DTC is set if there is abnormal resistance between the input terminals of the curtain air bag module (LH) (squib).
TROUBLESHOOTING HITS
- Damaged wiring harnesses or connectors
- Short to the ground in the curtain air bag module (LH) (squib) harness
- Malfunction of the SRS-ECU
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 "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 by dummy resistor connection.
(1)Disconnect the negative battery terminal.
(2)Use the flat-tipped screwdriver to pull out the locking button of D-17 curtain air bag module connector to the direction of the arrow. After releasing the lock, disconnect the connector.
(3)Connect the dummy resistor (Special tool: MB991865) to the resistor harness (Special tool: MB991884).
(4)Connect the resistor harness (special tool) to D-17 curtain air bag module connector.
(5)Connect the negative battery terminal.
(6)After erasing the diagnostic trouble code memory, check the diagnostic trouble code again.
(7)Disconnect the negative battery terminal.
Q. Is DTC B1452 set?
YES Go to Step 4.
NO Replace the left curtain air bag module (Refer to Removal and Installation.)
STEP 4. Resistance measurement at the C-125 SRS-ECU connector.
(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-125 SRS-ECU connector.
(3)DANGER:
To release C-125 SRS-ECU wiring harness side connector short spring in the following operations, disconnect D-17 air bag module connector in advance, and keep the squib circuit shorted.
Use the flat-tipped screwdriver to pull out the locking button of harness side connector.
After releasing the lock, disconnect the D-17 harness side connector
(4)
CAUTION:
The short spring may not be released due to the insufficient insertion. Therefore, insert the insulator for 4 mm (0.6 inch) or more.
Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminal 36, 37 and the short spring to release the short spring.
(5)Check for continuity between C-125 wiring harness side connector terminal No. 36, 37 and body ground.
It should be open circuit.
Q. Is it open circuit?
YES Go to Step 5.
NO Repair the wiring harness.
STEP 5. 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 DTC B1452 set?
YES Replace SRS-ECU (Refer to Service and Repair).
NO Intermittent Malfunction How to Cope With Intermittent Malfunctions).