DTC B1551: SRS Warning Light Drive Circuit System Fault 1 (Light does not Switch Off).: 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)

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 ).

Fig 1: Connecting Scan To Data Link Connector
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 2. Check the SRS warning light
1. Disconnect the negative battery terminal.
2. Disconnect the combination meter connector C-04.
3. Connect the negative battery cable.
4. Turn the ignition switch to the "ON" position.
Q: Does the SRS warning light go out?

YES : Go to Step 3.

NO : Replace the combination meter (Refer to COMBINATION METER ASSEMBLY ). Then go to Step 7.

Fig 2: Identifying Connector C-04 Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 3. Check the harness for short circuit between ignition switch connector C-303 (terminal No.2) and combination meter connector C-04 (terminal no.42).

Fig 3: Identifying Connector C-04 Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

Fig 4: Identifying C-303 Connector Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

NOTE: After inspecting junction block connectors C-205 and C-203, inspect the wiring harness. If intermediate connectors C-205, C-203 are damaged, repair or replace them. Refer to HARNESS CONNECTOR INSPECTION . Then go to Step 7.

Q: Is the harness wire between the ignition switch connector C-303 (terminal No.2) and combination meter connector C-04 (terminal no.42) in good condition?

YES : Go to Step 4.

NO : Repair the harness wire between ignition switch connector C-303 and combination meter connector C-04. Then go to Step 7.

Fig 5: Identifying C-203 And C-205 Connectors Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 4. Check combination meter connector C-05. Q: Is the connector correctly engaged?
YES : Go to Step 5.

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

Fig 6: Identifying Connector C-05 Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 5. Check SRS-ECU connector C-115. Q: Is the connector correctly engaged?
YES : Go to Step 6.

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

Fig 7: Identifying Connector C-115 Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 6. Check the harness for short circuit between SRS-ECU connector C-115 (terminal No.26) and combination meter connector C-05 (terminal no.11).
Q: Is the harness wire between the SRS-ECU connector C-115 (terminal No.26) and combination meter connector C-05 (terminal no.11) in good condition?

YES : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1551 sets, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU) ). Then go to Step 7.

NO : Repair the harness wire between SRS-ECU connector C-115 and combination meter connector C-05. Then go to Step 7.

Fig 8: Identifying Connector C-05 Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

Fig 9: Identifying Connector C-115 Terminals
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 7. 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 B1551 set?

YES : Return to Step 1.

NO : The procedure is complete.

Fig 10: Connecting Scan To Data Link Connector

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.