B1545
This document has been updated per Mitsubishi TSB# 06-52b-001DTC B1545: Occupant classification-ECU for Power Supply Circuit
DTC B1546: Occupant classification-ECU for Communication System
Occupant Classification Sensor Circuit Part 1:
Occupant Classification Sensor Circuit Part 2:
CIRCUIT OPERATION
The load data from the occupant classification sensor is classified with the occupant classification-ECU, and its classified information is send to SRS-ECU. The SRS-ECU determines the air bag deployment based on this classified information, and controls the power supply circuit to the inflator.
DTC SET CONDITIONS
These DTCs are set if communication between the occupant classification-ECU and the SRS-ECU is not possible or communication is faulty.
TROUBLESHOOTING HINTS
- Damaged wiring harnesses or connectors
- Malfunction of the occupant classification-ECU
- Malfunction of the SRS-ECU
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A
STEP 1. Measure the resistance at occupant classification-ECU connector D-35.
1. Disconnect the connector D-35.
2. Check for continuity between D-35 harness side connector terminals 2 and body ground.
It should be 1 ohms or less.
Q: Is the measured resistance 2 ohms or less?
YES: Then go to Step 2.
NO: Repair the wiring harness between occupant classification-ECU connector D-35 terminals 1 and the body ground. Then go to Step 6.
STEP 2. Measure the voltage at occupant classification- ECU connector D-35.
1. Disconnect the connector D-35.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 2 and ground. It should measure approximately 12 volts (battery positive voltage).
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 3.
NO: Go to Step 6.
STEP 3. Check the harness wires for open circuit or short circuit between occupant classification-ECU connector D-35 (terminal No.2) and ignition switch connector C-208 (terminal No.2).
NOTE: After inspecting intermediate connectors C-211 and C-214 inspect the wiring harness. If intermediate connectors C-211 and C-214 are damaged, repair or replace them.
Q: Are the harness wires between occupant classification-ECU connector D-35 (terminal No.2) and ignition switch connector C-208 (terminal No.2) in good condition?
YES: Then go to Step 4.
NO: Replace the harness wires between occupant classification-ECU connector D-35 and ignition switch connector C-208. Then go to Step 6.
STEP 4. Check the harness wires for open circuit or short circuit between SRS-ECU connector C-27 (terminal No.66) and occupant classification-ECU connector D-35 (terminal No.3).
Q: Are the harness wires between SRS-ECU connector C-27 (terminal No.66) and occupant classification-ECU connector D-35 (terminal No.3) in good condition?
YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1545 or B1546 sets, replace the front seat slide adjuster (Refer to Interior, Front Seat Assembly). Then go to Step 5.
NO: Replace the harness wires between SRS-ECU connector C-27 and occupant classification-ECU connector D-35. Then go to Step 6.
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 B1545 or B1546 set?
YES: Replace the SRS-ECU. Then go to Step 6.
NO: The procedure is complete.
STEP 6. 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 B1545 or B1546 set?
YES: Return to Step 1.
NO: The procedure is complete.