Initial Inspection and Diagnostic Overview

ABS INDICATOR LIGHT
1. If the system is OK, the ABS indicator light goes off two seconds after turning the ignition switch ON (II) without starting the engine. After starting the engine, the ABS indicator light comes on again and goes off after two seconds. This occurs because the ABS control unit is activated by the IG2 power source.
2. The ABS indicator light comes on when the ABS control unit detects a problem in the system. However, even though the system is normal, the ABS indicator light comes on, too, under the following conditions. To determine the actual cause of problem, question the customer about the problem, talking the following conditions into consideration.
- Only drive wheels rotate
- One drive wheel is stuck
- Vehicle spin
- ABS continues to operate for a long time
- Signal disturbance
3. When a problem is detected and the ABS indicator light comes on, there are cases when the indicator light stays on until the ignition switch is turned OFF, and cases when the indicator light goes off automatically when the system returns normal. For the DTC 61 and 62, the indicator light goes off automatically when the system returns normal. For all other codes, the indicator light stays on until the ignition switch is turned OFF.
4. For DTCs 12, 14, 16, 18, 21, 22, 23, 24, 51, 52 and 53, the indicator light goes off when the vehicle is driven again and the signals are OK after the ignition switch is turned from OFF to ON (II). However, if the DTC is erased, the CPU is reset and the indicator light goes off right aver the engine is started if the signals are OK.

DIAGNOSTIC TROUBLE CODE (DTC)
1. The DTC is not memorized if the CPU cannot be activated or the CPU fails and the indicator light comes on.
2. The memory can hold any number of DTCs. However, when the same DTC is detected more than once, the later one is written over the old one. Therefore, when the same problem is detected repeatedly, it is memorized as one DTC.
3. The DTCs are indicated in the order of ascending number, not in the order they occur.
4. The DTCs are memorized in the EEPROM (non-volatile memory). Therefore, the memorized DTCs cannot be canceled by disconnecting the battery. Perform the specified procedures to erase the DTCs.

SELF-DIAGNOSIS
1. The self-diagnosis can be classified into two categories.
- Initial diagnosis: Performed right after the engine starts and until the ABS indicator light goes off.
- Regular diagnosis: Performed right after the initial diagnosis until the ignition switch is turned OFF.
2. When a problem is detected by self-diagnosis, the system.
- Turns the ABS indicator light ON
- Memorizes the DTC
- Turns the fail-safe relay OFF
- Stops ABS control

KICKBACK
1. The motor operates when the ABS is functioning, and the fluid in the reservoir is forced out to the master cylinder causing kickback at the brake pedal.

PUMP MOTOR
1. The pump motor operates when the ABS is functioning.
2. The ABS control unit checks the pump motor operation during initial diagnosis and vehicle starts. You may hear the faint operation sound at this time, but it is normal.

BRAKE FLUID REPLACEMENT/AIR BLEEDING
1. Brake fluid replacement and air bleeding procedures are the same as vehicles without ABS. To ease bleeding, start with the front wheels.

TROUBLESHOOTING
1. The troubleshooting flowcharts procedures assume that the cause of the problem is still present and the ABS indicator light is still on. Following the flowchart when the ABS indicator light does not come on can result in incorrect judgment.
2. Question the customer about the conditions when the problem occurred, and try to reproduce the same conditions for troubleshooting.
Find out when the ABS indicator light came on, such as during initial diagnosis, during ABS control, aver ABS control, when the vehicle started, when vehicle speed was at 19 mph (30 km/h), when the problem continued for a few seconds or a few minutes, etc.
3. When the ABS indicator light does not come on during the test-drive, but the troubleshooting is performed based on the DTC, check for the loose connectors, poor contact of the terminals, etc. before troubleshooting.
4. After troubleshooting, erase the DTC and test-drive the vehicle. Be sure that the ABS indicator light does not come on.
5. The connector illustrations show the female connectors with a single outline and the male connectors with a double outline.