DTC 43
SRS Warning Light Drive Circuit System Fault 1 (Light Does Not Illuminate.)/SRS Warning Light Drive Circuit System Fault 1SRS Warning Light Drive Circuit:
Connectors:
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 DTC 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, DTC 43 will be automatically erased, and the SRS warning light will go out.
- This DTC is output when a short to ground occurs in the harness between the SRS warning light and SRS-ECU while the SRS-ECU is monitoring the light and the light is ON.
- This DTC 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, DTC 44 will be automatically erased, and the SRS warning light will go out.
TROUBLESHOOTING HINTS
- Damaged wiring harnesses of connectors
- Blown bulb (for DTC 43)
- Malfunction of the SRS-ECU
- Malfunction of the combination meter (for DTC 43)
DIAGNOSIS
STEP 1. Check the SRS warning light line at SRS-ECU connector C-137 by backprobing.
1. Do disconnect the connector C-137.
2. Connect the negative battery cable.
3. Turn the ignition switch to "ON" position.
4. Connect terminal 4 to ground by backprobing.
- The SRS warning light should illuminate.
Q: Does the SRS warning light illuminate?
YES: Replace the SRS-ECU. Then go to Step 6.
NO: Go to Step 2.
STEP 2. Check the SRS warning light bulb.
Q: Has the SRS warning light bulb blown?
YES: Replace the SRS warning light bulb. Then go to Step 6.
NO: Go to Step 3.
STEP 3. Check the harness wires between the ignition switch (IG1) and SRS-ECU connector C-137.
NOTE: After inspecting intermediate connectors C-101, C-102, C-308, C-301 inspect the wiring harness. If intermediate connectors C-101, C-102, C-308, C-301 are damaged, repair or replace them. Refer to Harness Connector Inspection. Then go to Step 6.
Q: Are the harness wires between the ignition switch (IG1) and SRS-ECU connector C-137 in good condition?
YES: Go to Step 4.
NO: Repair them. Then go to Step 6.
STEP 4. 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 3 and ground by backprobing.
- Should be less than 2 ohm.
Q: Is the resistance between terminal 3 and ground less than 2 ohm?
YES: Go to Step 6.
NO: Go to Step 5.
STEP 5. 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 6.
NO: Repair them. Then go to Step 6.
STEP 6. Check for DTC.
Q: Is any of DTC 43 or 44 output?
YES: There is no action to be taken.
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.)