NO.6 BOTH ABS WARNING LIGHT AND BRAKE SYSTEM WARNING LIGHT STAY ON MORE THAN 4 s WITH IGNITION SWITCH ON


id040300901600

6

Both ABS warning light and BRAKE system warning light stay on more than 4 s with ignition switch on.

[TROUBLESHOOTING HINTS]

• ABS (ABS/TCS) HU/CM detects ABS proportioning system malfunction.

• ABS (ABS/TCS) HU/CM detects low voltage in power supply (ABS (ABS/TCS) CM ingestion terminal Z voltage is below about 9 to 10 V).

• ABS (ABS/TCS) HU/CM does not operate.

• Malfunction of communication network.

Diagnostic procedure

STEP

INSPECTION

ACTION

1
INSPECT ABS (ABS/TCS) HU/CM POWER SUPPLY FUSE
Is ABS (ABS/TCS) HU/CM ignition power supply fuse normal?
Yes
Go to next step.
Check for a short to ground on blown fuse's circuit.
No
Repair or replace as necessary.
Install appropriate amperage fuse.
2
INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC-2 FOR CONTINUITY AND SHORTS
Perform DTC inspection.
Is error message displayed regarding communication between ABS (ABS/TCS) HU/CM and WDS or equivalent?
Yes
If a communication error message is displayed even after inspecting according to procedure displayed on WDS or equivalent, go to step 8.
No
Go to next step.
3
INSPECT FOR DTCS IN ABS (ABS/TCS) HU/CM
Have DTCs been recorded in memory?
 
Yes
Perform inspection using appropriate DTC.
No
Go to next step.
4
INSPECT PID/DATA IN ABS (ABS/TCS) HU/CM
Inspect the following items using WDS or equivalent PID/DATA monitor function.
• ABS_LAMP (ABS warning light)
• BRAKE_ LMP (BRAKE system warning light)
• ABS_VOLT (power supply voltage)
Is ABS_LAMP and BRAKE_LMP ON after more than 4 s with ignition switch on?
Yes
Go to Step 7.
No
Go to next step.
5
INSPECT ABS (ABS/TCS) HU/CM IGNITION POWER SUPPLY SYSTEM (TERMINAL Z)
Inspect the voltage for PID/DATA monitor ABS_VOLT item.

Specification: approx.10 V

Is voltage within specification?
Yes
Replace ABS (ABS/TCS) HU/CM (open or short in ground circuit in ABS HU/CM)
No
Go to next step.
6
INSPECT BATTERY
Is battery voltage normal?
Yes
Go to next step.
No
Inspect battery and charging system.
7
INSPECT CHARGING SYSTEM
Is battery voltage normal with electrical load (A/C, headlight, etc.) on and engine idling?
Yes
Go to next step.
No
Inspect charging system (drive belt tension, generator, etc.).

*8

INSPECT WIRING HARNESS BETWEEN ABS (ABS/TCS) HU/CM POWER SUPPLY AND ABS (ABS/TCS) HU/CM FOR CONTINUITY
Disconnect ABS (ABS/TCS) HU/CM connector.
Turn the ignition switch to ON.
Is voltage approx. 12 V at connector terminal Z?
Yes
Go to next step.
No
Inspect for connection of ABS (ABS/TCS) HU/CM connector securely.

*9

INSPECT WIRING HARNESS BETWEEN ABS (ABS/TCS) HU/CM GROUND FOR CONTINUITY
Turn ignition switch LOOK.
Is there continuity between connector terminal AC and ground?
Yes
If a malfunction error message is displayed on WDS or equivalent in Step 1 inspection, go to next step.
If a malfunction error message is not displayed on WDS or equivalent in Step 1 inspection, troubleshooting is completed.
No
Repair wiring harness between ABS (ABS/TCS) HU/CM and ground.

*10

INSPECT WIRING HARNESS BETWEEN ABS (ABS/TCS) HU/CM AND DLC-2 FOR CONTINUITY
Is there continuity between connector terminal O, R and DLC-2?
Yes
Go to next step.
No
Repair wiring harness between ABS (ABS/TCS) HU/CM and DLC-2.
11
INSPECT WIRING HARNESS BETWEEN ABS (ABS/TCS) HU/CM AND DLC-2 FOR SHORT TO BATTERY
Is voltage approx. 12 V at connector terminal O, R?
Yes
Repair wiring harness between ABS (ABS/TCS) HU/CM and DLC-2.
No
Go to next step.
12
INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC-2 FOR SHORT TO GROUND
Is there continuity between connector terminal O, R and ground?
Yes
Repair wiring harness between ABS (ABS/TCS) HU/CM and DLC-2.
No
Replace ABS (ABS/TCS) HU/CM (communication circuit malfunction in ABS (ABS/TCS) HU/CM)