ABS Hydraulic Unit / Control Module Assembly Description
Self-Diagnosis Function
ABS control module diagnoses conditions of the system component parts (whether or not there is any abnormality) all the time and indicates the results (warning of abnormality occurrence and DTC) through the “ABS” warning lamp as described.
1) When ignition switch is turned ON, “ABS” warning lamp lights for 2 seconds to check lamp and circuit.
2) When no abnormality has been detected (the system is in good condition), “ABS” warning lamp turns OFF after 2 seconds.
3) When an abnormality in the system is detected, ABS warning lamp lights and the area where that abnormality lies is stored in the memory in ABS control module.
4) When diag. switch terminal (2) of monitor connector (1) is grounded, the abnormal area is output as DTC.
DTC is indicated by flashing pattern of “ABS” warning lamp. (Refer to the following table.)
System condition Diagnosis switch terminal ABS warning lamp
In good condition at present No trouble in the past Open OFF
Grounded DTC 12
Trouble occurred in the past Open OFF
Grounded History DTC
Abnormality exists at present No trouble in the past Open ON
Grounded Current DTC
Trouble occurred in the past Open ON
Grounded Current and history DTC
For procedure to clear all DTC’s, refer to DTC Clearance .
3. Ground terminal 4. Service wire
Fail-Safe Function
When an abnormality occurs (an abnormal DTC is detected), ABS control module turns OFF the solenoid valve relay (transistor) which supplies power to ABS hydraulic unit. Thus, with ABS not operating, brakes function just like the brake system of the vehicle without ABS.