Inspection Procedure 5: Brake warning light does not illuminate when the ignition switch is turned to ON position (engine stopped): Diagnosis

WARNING: This page is about a different car, the 2015 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.

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. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.

Q: Is the check result normal?
1. YES: Go to Step 2.
2. NO: Repair the CAN bus lines. (Refer to CAN BUS DIAGNOSTICS TABLE .) Then go to Step 7.
STEP 2. Using scan tool MB991958, check the DTC
Use scan tool to check the DTC for the ASC system.

Q: Is the DTC set?
1. YES: Carry out the diagnosis for the DTC (Refer to DIAGNOSTIC TROUBLE CODE CHART ).
2. NO: Go to Step 3.
STEP 3. Actuator test of combination meter
Perform the following actuator test by the combination meter system, and check if the brake warning light illuminates (Refer to Combination Meter - ACTUATOR TEST TABLE ).
- Item No. 07: Indicator 1
Q: Is the check result normal?
1. YES: Go to Step 4.
2. NO: Diagnose the combination meter (Refer to Combination Meter - TROUBLE SYMPTOM CHART ). Then go to Step 7.
STEP 4. Using scan tool MB991958, check the other system DTC
Using scan tool, check that DTC U0141 is not set by the combination meter system.

Q: Is the DTC set?
1. YES: Diagnose the combination meter (Refer to DTC U0141: ETACS CAN TIMEOUT ). Then go to Step 7.
2. NO: Go to Step 5.
STEP 5. Using scan tool MB991958, check the other system DTC
Using scan tool, check that DTC U0121 is not set by the ETACS system.

Q: Is the DTC set?
1. YES: Perform troubleshooting on ETACS-ECU (Refer to DTC U0121: ASC-ECU CAN TIMEOUT ). Then go to Step 7.
2. NO: Go to Step 6.
STEP 6. Retest the system.
Q: Does the brake warning light turn ON and OFF
1. YES: Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
2. NO: Replace the hydraulic unit (integrated with ASC-ECU) (Refer to HYDRAULIC UNIT ), and then go to Step 7.
STEP 7. Retest the system.
Q: Does the brake warning light turn ON and OFF normally?
1. YES: The procedure is complete.
2. NO: Return to Step 1.