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Inspection Procedure 3: The brake warning light does not go out (ABS warning light is OFF) although the parking brake is released.
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
OPERATION
  • The combination meter illuminates the brake warning light when the parking brake is applied.
  • When reduction of the brake fluid amount is detected, the brake fluid level switch is turned from ON to OFF. ETACS-ECU monitors the brake fluid level switch, and instructs the combination meter via the CAN bus line to illuminate the brake warning light.
 
 
 
TROUBLESHOOTING HINTS
  • The brake pad thickness is at the limit value or less.
  • The brake fluid amount is at the "MIN" level or lower.
  • Parking brake malfunction
  • Damaged wiring harness and connectors
  • Malfunction of brake fluid level switch
  • Combination meter malfunction
  • Malfunction of ETACS-ECU
 
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Scan tool (M.U.T.-IIISE) CAN bus diagnostics.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Turn on the power supply mode of the electric motor switch.
(3) Diagnose the CAN bus line.
(4) Turn off the power supply mode of the electric motor switch.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
 
STEP 2. Scan tool (M.U.T.-IIISE) DTC for other systems.
Use scan tool (M.U.T.-IIISE) to check that the DTC is set in the combination meter and ETACS-ECU.
Is the DTC set?
Carry out the diagnosis for the DTC.
Go to Step 3.
 
STEP 3. Brake fluid level check.
Check that the brake fluid is filled up to the "MIN" level or higher.
Is the check result normal?
Go to Step 5.
Go to Step 4.
 
STEP 4. Brake pad check.
Refer to GROUP 35A - On-vehicle Service/Brake Pad Check .
Is the check result normal?
Fill the brake fluid up to the "MAX" level. Then go to Step 5.
Replace the brake pad (Refer to GROUP 35A - On-vehicle Service/Brake Pad Replacement ). Then go to Step 10.
 
STEP 5. Scan tool (M.U.T.-IIISE) data list for other system.
Check the ETACS-ECU system data list.
 
Item No. Item nameNormal condition
279Brake fluid switchON
Is the check result normal?
Go to Step 10.
: Go to Step 6.
 
STEP 6. Brake fluid level switch check.
Refer to GROUP 35A - On-vehicle Service/Brake Fluid Level Switch Check .
Is the check result normal?
Go to Step 7.
Replace the reservoir tank assembly (Refer to GROUP 35A - Master Cylinder Assembly and Brake Booster ). Then go to Step 10.
 
STEP 7. Resistance measurement at brake fluid level switch connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the brake fluid level switch connector (ground terminal) and the body ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 9.
Go to Step 8.
 
STEP 8. Check of open circuit in ground line between brake fluid level switch connector and the body ground.
Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.
 
STEP 9. Check of short to power supply, short to ground, and open circuit in BFSW line between ETACS-ECU connector and brake fluid level switch connector.
Is the check result normal?
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 10.
Repair the connector(s) or wiring harness.
 
STEP 10. Retest the system.
Does the brake warning lamp turn ON and OFF normally according to the parking brake operation?
This diagnosis is complete.
Replace the combination meter assembly (Refer to GROUP 54A - Combination Meter ).