DTC 41

DTC 41: IG1 Power Supply Circuit System (Fuse No.2 Circuit)

IG1 Power Supply Circuit System (Fuse No.2 Circuit) Part 1:

IG1 Power Supply Circuit System (Fuse No.2 Circuit) Part 2:

CIRCUIT OPERATION
- The SRS-ECU is powered from the ignition switch (IG1).
- The SRS-ECU power is supplied from two circuits. Even if one circuit is shut off, the air bag can inflate.

DTC SET CONDITIONS
This DTC is set if the voltage between the IG1 terminals (fuse No.2 circuit) and ground is lower than a predetermined value for a continuous period of five second or more. However, if the vehicle condition returns to normal, DTC number 41 will be automatically erased, and the SRS warning light will switch off.

TROUBLESHOOTING HINTS
- Damaged wiring harnesses or connectors
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991911: M.U.T.-III Main Harness B




STEP 1. Check junction block fuse number 2.

Q: Is the fuse burned out?

YES: Go to Step 4.

NO: Go to Step 2.

STEP 2. Check the power supply circuit for open circuit at the SRS-ECU connector C-12.

1. Disconnect the negative battery terminal.




2. Disconnect SRS-ECU connector C-12.
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 C-12 harness connector terminal 16 and body ground.
Voltage should measure 9 volts or more.

Q: Is the measured voltage within the specified range?

YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 41 set, replace the SRS-ECU. Then go to Step 10.

NO: Go to Step 3.







STEP 3. Check the harness for open circuit between SRS-ECU connector C-12 (terminal No.16) and the ignition switch connector C-208 (terminal No.2).






NOTE: After inspecting intermediate connectors C-214 and C-211, inspect the wiring harness. If intermediate connectors are damaged, repair or replace them. Refer to Harness Connector Inspection.

Q: Is harness between SRS-ECU connector C-12 (terminal No.16) and the ignition switch connector C-208 (terminal No.2) in good condition?

YES: Go to Step 10.

NO: Repair the harness wire between SRS-ECU connector C-12 and the ignition switch connector C-208. Then go to Step 10.

STEP 4. Check for a burned-out fuse.

1. Replace the fuse.
2. Turn the ignition switch to the "ON" position, wait for at least one minute and then turn the ignition switch to the "LOCK" (OFF) position.
3. Check the fuse.

Q: Is the fuse in good condition?

YES: Go to Step 10.

NO: Go to Step 5.

STEP 5. Check the SRS-ECU power supply circuit for short circuit to ground at the junction block connector C-214.




1. Disconnect junction block connector C-214, and measure at the wiring harness side.






CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

2. Check for continuity between terminal 24 and body ground. It should be open circuit.

Q: Does continuity exist?

YES: Go to Step 8.

NO: Go to Step 6.

STEP 6. Check the fuse number 2-related circuit at junction block connector C-214.




1. Disconnect junction block connector C-214, and measure at the wiring harness side.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.




2. Check for continuity between C-214 harness connector terminal 25 and body ground. It should be open circuit.

Q: Does continuity exist?

YES: Go to Step 7.

NO: Check the other circuit, which flows through multi-purpose fuse number 2.







STEP 7. Check the harness for short circuit to ground between junction block connector C-214 (terminal No.25) and combination meter connector C-01 (terminal No.9).






NOTE: After inspecting intermediate connector C-23, inspect the wiring harness. If intermediate connectors are damaged, repair or replace them. Refer to Harness Connector Inspection.

Q: Is the harness wire between junction block connector C-214 (terminal No.25) and combination meter connector C-01 (terminal No.9) in good condition?

YES: Go to Step 10.

NO: Repair the harness wire between junction block connector C-214 and combination meter connector C-01. Then go to Step 10.

STEP 8. Check the power supply circuit for short circuit to ground at the SRS-ECU connector C-12.







1. Disconnect SRS-ECU connector C-12, and measure at the wiring harness side.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

2. Check for continuity between terminal 16 and body ground. It should be open circuit.

Q: Is the circuit normal?

YES: Go to Step 9.

NO: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 41 set, replace the SRS-ECU. Then go to Step 10 .







STEP 9. Check the harness for short circuit to ground between SRS-ECU connector C-12 (terminal No.16) and junction block connector C-214 (terminal No.24).

Q: Are the harness wires between SRS-ECU connector C-12 (terminal No.16) and junction block connector C-214 (terminal No.24) in good condition?

YES: Go to Step 10.

NO: Repair the harness wires between SRS-ECU connector C-12 and junction block connector C-214. Then go to Step 10.

STEP 10. 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 41 set?

YES: Return to Step 1.

NO: The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to How to Use Troubleshooting/INSPECTION Service Points - How to Cope with Intermittent Malfunction).