C1009

DTC C1009: Low brake fluid level

Brake Fluid Level Switch Circuit:

CAUTION: If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.

CIRCUIT OPERATION
ASC-ECU receives the low level signal of the brake fluid level switch in ETACS-ECU via the CAN bus lines. When the brake fluid level is lower than the specified.

DTC SET CONDITIONS
This diagnostic trouble code is set when the brake fluid level is lower than the specified.

PROBABLE CAUSES
^ Low brake fluid level
^ Brake fluid level switch malfunction
^ Brake pad wear
^ Damaged wiring harness and connectors
^ Malfunction of ETACS-ECU
^ ASC-ECU malfunction

DIAGNOSIS

Required Special Tools:
^ MB991958: Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A

STEP 1. M.U.T.-III CAN bus diagnostics
Use scan tool to diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. On completion, go to Step 2.

STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Q: Is DTC C1009 set?
YES: Go to Step 3.
NO: The procedure is complete.

STEP 3. Brake fluid level check
Check that the brake fluid level is higher than the lower limit.
Q: Is the check result normal?
YES: Go to Step 4.
NO: Add brake fluid as necessary.

STEP 4. Brake pad check
Check that the brake pad is thicker than the limit.
Q: Is the check result normal?
YES: Go to Step 5.
NO: Replace the brake pad.

STEP 5. Voltage measurement at C-312 ETACS-ECU connector
(1) Turn the ignition switch to the ON position.
(2) Measure the voltage between the terminal No. 1 and the body ground.
OK: 12 volts (Battery voltage)

Q: Is the check result normal?
YES: Go to Step 7.
NO: Go to Step 6.

STEP 6. Connector check: C-312 ETACS-ECU connector, A-09 brake fluid level switch connector
Q: Is the check result normal?
YES: The short circuit between the C-312 ETACS-ECU connector terminal No. 1 and the A-09 brake fluid level switch connector terminal No. 1 may be present. Repair the wiring harness between the C-312 ETACS-ECU connector terminal No. 1 and the A-09 brake fluid level switch connector terminal No. 1.
NO: Repair the defective connector.

STEP 7. Brake fluid level switch check
Q: Is the check result normal?
YES: Go to Step 8.
NO: Replace the brake fluid level switch.

STEP 8. Check whether the diagnostic trouble code is reset.
Q: Is DTC 1009 set?
YES: Replace the ASC-ECU.
NO: The procedure is complete.