Honda Civic 1998 Service Manual page 876

Troubleshooting Precautions
ABS Indicato. Light
1. 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 can come on. too, under the following conditions. To determine the
actual cause of problem, question the customer about the problem, taking the following conditions into considera-
I | o n .
. Signal disturbance
. W h e e l s p i n
. Only drive wheels rotate
. Battery voltage Iluctuates
2. When a problem is detected and the ABS indicator light comes on, the indicator light can stay on until the ignition
switch is turned off, or it can automatically go off, depending on the mode.
.
Lightstayson until the ignition switch isturned off: Whenthesystem is inthesystem down mode.
. Light automatically goes off:
When the system is in the control inhibition mode.
(refer to symptom-to-system chart)
3. The ABS indicator light stays on when the system is reactivated without erasing the DTC, but it goes off after starting
the car.
When the wheel sensor system is faulty and the ABS indicator light comes on, the algorithm of the system automatically
turns off the ABS indicator light after the wheel speed signal returns to the normal speed. While, when the DTC is erased.
the CPU is reset and the ABS indicator light goes off when the system checked out normal by the initial dlagnosis.
Therefore, test-drive the car after servicing the wheel sensor system, and be sure that the ABS indicator light does not
come on.
4. When the ABS control unit outputs battery voltage to gauge assembly. the ABS indicator light goes off,
Diagnostic Troublo Code (DTCI
1. The diagnostic trouble code (DTC) is memorized when a problem is detected and the ABS indicator light does not go
off, or when the ABS indicator light comes on.
The DTC is not memori?ed when the ABS indicator light comes on unless the CPU is activated.
2.
The memory can hold any number of DTCs. However, when the same DTC is detected twice or more, the later one is
written over the old one.
Therefore, when the same problem is detected repeatedly, it is recorded as one DTC.
3. The DTCS are indicated in the order of ascending number, not in the order they occur.
4. The DTC$ 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.
Self-diagnosis
1. The self-diagnosis can be classifield into these four catego.ies.
.
Initial diagnosis: Performed rig ht after the engine sta rts and until the ABS ind icator light goes ofJ
. Except ABS control: Performed when the ABS is not functioning.
. During ABS control: Performed when the ABS is functioning.
. During warning;
Performed when the ABS indicator light is ON.
2. The system performs the following controls when a problem is detected by the self-diagnosis.
! ABS indicator light ON
.
Memory of DTC
.
Mode change to the "system down mode" or the "control inhibition mode".
MODE
ABS INDICATOR LIGHT
M A I N
RELAY
S O L E N O I D
VALVE
C P U Restart condition
DTC
SYSTEM
DOWN
O N
N o
operatron
Drive
i n h i b i t i o n
Operation*1
lgnition
swatch
OFF * ON
Memory
CONTROL
I N H I B I T I O N
ON
N o
opera on
Drive
inhibition
Operation
Automatic
Memory
*1: Except CPU failure
19-42