B1407
DTC B1407: Front Impact Sensor (RH) Power Supply Circuit SystemFront Impact Sensor Circuit:
CIRCUIT OPERATION
The front impact sensor includes an analog G sensor and CPU, etc. The CPU monitors the analog G sensor output signal. If the CPU judges that the front air bags should be deployed, it sends a fire signal to the SRS-ECU to deploy the front air bags. In addition, the CPU diagnoses the internal components of the front impact sensor. If a malfunction occurs, it requests the SRS-ECU to set a diagnostic trouble code.
DTC SET CONDITIONS
This DTC will set when the power supply voltage to the front impact sensor (RH) remains less than a pre-determined value for five seconds. However, if the system returns to normal condition, code number B1407 will be erased automatically and the SRS warning light will go out.
TROUBLESHOOTING HINTS
- Damaged wiring harness or connectors
- Malfunction of the front impact sensor (RH)
- Malfunction of the SRS-ECU
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A (Vehicles with CAN communication)
- MB991223 (MB991222): Harness set (Probe)
STEP 1. 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 2.
NO: There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to How to Cope with Intermittent Malfunction).
STEP 2. Check the front impact sensor (RH) power supply circuit. Measure the voltage at the front impact sensor (RH) connector A-27.
1. Disconnect the negative battery terminal.
2. Disconnect front impact sensor (RH) connector A-27, and measure at the wiring harness side.
3. Connect the negative battery terminal.
4. Turn the ignition switch to the "ON" position.
CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
5. Measure the voltage between A-27 harness side connector terminal 1 and ground.
Voltage should measure 9 volts or more
Q: Is the measured voltage within the specified range?
YES: Replace the front impact sensor (RH). Then go to Step 4.
NO: Go to Step 3.
STEP 3. Check the harness wires for open circuit or short circuit between SRS-ECU connector C-115 (terminal No.47 and 48) and front impact sensor (RH) connector A-27 (terminal No.1 and 2).
NOTE: After inspecting intermediate connectors C-14 inspect the wiring harness. If the intermediate connectors C-14 is dam-aged, repair or replace it.
Q: Are the harness wires between SRS-ECU connector C-115 (terminal No.47 and 48) and front impact sensor (RH) connector A-27 (terminal No.1 and 2) in good condition?
YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1407 sets, replace the SRS-ECU. Then go to Step 4.
NO: Replace the harness wires between SRS-ECU connector C-115 and front impact sensor (RH) connector A-27.Then go to Step 4.
STEP 4. 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 B1407 set?
YES: Return to Step 1.
NO: The procedure is complete.