Troubleshooting Precautions - Honda Civic Service Manual

Troubleshooting Precautions
ABS Indicator Light
I 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 the problem, question the customer about the problem, taking the following conditions into consider-
ation.
. Signal disturbance
. Wheel soin
. Only drive wheels rotate
.
Battery voltage fluctuates
2. When a problem is detected and the ABS indicator light comes on, the indicator light can stay on untat the ignition
switch is turned off, or it can automatically go off, depending on the mode.
.
Lightstayson until the ignition switch isturned off;When the system is inthesvstem down mode.
o 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 check€d out normal by the initial diagnosis.
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 the gauge assembty, the ABS indicator light goes off.
Diagnostic Trouble Code (DTC)
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 memorized when the ABs indicator right comes on unress 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 thev occur.
4. The DTCS are memorized in the EEpROM {non-volatile memorv}.
Therefore, the memorized DTCS cannot be canceled by disconnecting the battery. perform the specified orocedures to
erase.
Solf-diagnosis
1. The self-diagnosis can be classifield into these four categories:
'
Initial diagnosis;
Performed right after the engine sta rts and untiltheABs indicator light goes off.
o 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
MAIN
RELAY
SOLENOID
VALVE
CPU
Restart condition
DTC
SYSTEM
DOWN
O N
N o
operal|on
Drive
inhibition
Operation+r
lgnition
switch
OFF - ON
Memory
CONTROL
I N H I B I T I O N
O N
N o
operat|on
Orive
inhibition
Operation
Automatic
Memory
*1: Except CPU failure
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