DTC 41

IG1 power circuit system (fuse No.13 circuit)

IG1 Power Circuit (fuse No.13 Circuit Or No.15 Circuit):

CIRCUIT OPERATION
- Power for the SRS warning light is supplied from the ignition switch (IG1) circuit.
- The SRS warning light illuminates when the ignition switch is turned "ON" and goes out after approximately seven seconds if there is not a malfunction in the SRS system.
- The SRS-ECU judges how severe a collision is by detecting signals from the left and right side impact sensors and the analog G-sensor. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the safing G-sensor is on, the SRS air bag will inflate.

DTC SET CONDITIONS
- This diagnostic trouble code is output when an open circuit is detected for a continuous period of five seconds while the SRS-ECU is monitoring the SRS warning light and the light is OFF. (transistor OFF.) However, if the vehicle condition returns to normal, diagnostic trouble code number 43 will be automatically erased, and the SRS warning light will go out.
- This diagnostic trouble code is output when a short to ground occurs in the harness between the SRS warning light and SRS-ECU while SRS-ECU is monitoring the light and the light is ON.
- This diagnostic trouble code is output under one of the following cases while the SRS-ECU is monitoring the warning light drive circuit:
- When a short circuit occurs in the warning light drive circuit.
- When a malfunction is detected in the output transistor inside the SRS-ECU.

However, if the vehicle returns to normal condition, diagnostic trouble code 44 will be automatically erased, and the SRS warning light will go out.

TROUBLESHOOTING HINTS
- Damaged wiring harnesses of connectors
- Blown bulb (for code number "43")
- Malfunction of the SRS-ECU
- Malfunction of the combination meter (for code number "43")

DIAGNOSIS

STEP 1. Check the ignition switch (IG1) line at the SRS-ECU connector C-137 by backprobing.
1. Do disconnect the connector C-137.
2. Connect the negative battery terminal.
3. Turn the ignition switch to "ON" position.




4. Measure the voltage between terminal 12 (for DTC 41) or 9 (for DTC 42) and the ground by backprobing.
- Voltage should be 9 volts or more

Q: Is the voltage 9 volts or more?

YES: Go to Step 3.
NO: Go to Step 2.







STEP 2. Check the harness wires between the ignition switch (IG1) and SRS-ECU connector C-137.

NOTE: After inspecting intermediate connectors C-301 and C-303, inspect the wiring harness. If intermediate connectors are damaged, repair or replace them. Refer to Harness Connector Inspection. Then go to Step 5.

Q: Are harness wires between the ignition switch (IG1) and SRS-ECU connector C-137 in good condition?

YES: Go to Step 5.
NO: Repair them. Then go to Step 5.




STEP 3. Check the ground line at the SRS-ECU connector C-137 by backprobing.
1. Do disconnect the connector C-137.
2. Measure the resistance between terminal 7 and ground by backprobing.

Q: Is the resistance between terminal 3 and ground less than 2 ohm?

YES: Replace the SRS-ECU. Then go to Step 5.
NO: Go to Step 4.




STEP 4. Check the harness wires between SRS-ECU connector C-137 and ground.

Q: Are the harness wires between SRS-ECU connector C-137 and ground in good condition?

YES: Go to Step 5.
NO: Repair them. Then go to Step 5.

STEP 5. Check for DTC.

Q: Is any of DTC 41 or 42 output?

YES: Replace the SRS-ECU.
NO: This diagnosis is complete. (If no malfunctions are not found in all steps, an intermittent malfunction is suspected. Refer to INTRODUCTION, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.)