ABS Control
The ABS control unit detects the wheel speed based on the wheel sensor signal it received, then it calculates the vehicle
speed based on the detected wheel speed. The control unit detects the vehicle speed during deceleration based on the
rate of deceleration.
The ABS control unit calculates the slip rate of each wheel, and it transmits the control signal to the modulator unit
solenoid valve when the slip rate is high
The pressure reduction control has three modes: pressure reducing, pressure retaining, and pressure intensi{ying modes.
Self-diagnosis Function
The ABS control unit is equipped with a main cPU and a sub cPU, that check each other for problems.
The CPUs check the circuit of the system.
When the CPUS detect failure, they shift to the "system down mode" or the "control inhibition mode".
The self-diagnosis can be classitied into these four categories:
O: Initial diagnosis
O: Except ABS control
O; During ABS control
@: During warning
On-board Diagnosis Function
The ABS system can be diagnosed with the Honda PGM Tester.
The ALB Checker cannot be used with this system. For air bleeding. and checking wheel sensor signals, use the Honda
PGIM Tester. See the Honda PGM Tester user's manuals for specific operating instructions.
(cont'd)
19-29
ABS CONTROL I-INIT
MODEABSINDICATOR LIGHTMAIN
RE LAY
SOLENOID
VALVERestan conditionDTC
SYSTEM
DOWNONNo
operatron
Drive
inhibitionOperation*rlgnition
switchOFF - oN (ll)Memory
CONTROL
INHIBITIONONNo
operaton
Drive
inhibitionOperationAutomaticlVemory
*1: Except CPU failure
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Troubleshooting Precautions
ABS lndicalor
1 lf the system is oK, the ABS indicator goes off two seconds after turning the ignition switch oN 1l) wathout staningthe engine, and then comes on again and goes off after two seconds. This occurs because the ABS control unit isturned on by the lG2 power source.2. The ABS indicator comes on when the ABS control unit detects a problem in the system. However, even thouoh thesystem is operating properly, the ABs indicator will come on too, under the following conditions:. Signal disturbance
. Wheel spin
. Only drive wheels rotate. Battery voltage fluctuates
To determine the actual cause of the problem, question the customer about the problem, taking these conditions intoconsideration:
3 When a problem is detected and the ABS indicator comes on, the indicator can stay on until the ignition switch isturned OFF, or it can automatically go off, depending on the mode.. Indicator stays on untilthe ignition switch is turned off: When the system is in the system down mode.. Indicator automatically goes off: When the system is in the control inhibition mode.4 The ABS indicator stays on when the system is reactivated without erasing the DTC, but it goes off after starting thevehicle.
When the wheel sensor system is faulty and the ABS indicator comes on. the algorithm of the system automatically turnsoff the ABS indicator after the wheel speed signal returns to the normal speed. Also, when the DTc is erased, the cpu isreset and the ABS indicator goes off when the system checked out normal by the initial diagnosis.Therefore, test-drive the vehicle after servicing the wheel sensor system. and be sure that the ABS indicator does notcome on.
5 When the ABS control unit outputs battery voltage to the gauge assembly, the ABS indicator ooes off.
Diagnostic Trouble Code (DTCI
1. The diagnostic trouble code (DTc) is memorized when a problem is detected and the ABS indicator does not go off,or when the ABS indicator comes on.The DTc is not memorized when the ABS indicator 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 tater one iswritten 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 DTCS are memorized in the EEPROM (non-volatile memorv).Therefore, the memorized DTcs cannot be canceled by disconnecting the battery. perform the specified procedures toerase the DTCS.
Self-diagnosis
1. Self-diagnosis can be classified into these four categories:' Initial diagnosis: Performed right after the eng ine starts and untir theABS indicator goes off.. 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 is ON.2. The system performs the fo|owing contrors when a probrem is detected by the serf-diagnosis:. ABS indicator ON. Memorv of DTC. Mode changetothe "system down mode,, or the ,,control inhibition mode,,.
MODEABS INDICATORMAIN
RELAY
SOLENOID
VALVECPURestart conditionDTC
SYSTEM
DOWNONNo
operation
Drive
inhibitionOperation*rlgnition
switchoFF - ON l)Memory
CONTROL
INHIBITIONONNo
operal|on
Drive
inhibitionOperationAutomaticlMemory
*1: Except CPU failure
19-36
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Troubleshooting
Erasing the DTC Memory
To erase the DTC{S) from the SRS unit, use a Honda
PGM Tester (see the Honda PGM Tester SRS Vehicle
System Supplement) or the following procedure.
1. Make sure the ignition switch is OFF.
2. Connect the SCS service connector to the MES con,
nector (2P). Do not use a jumper wire.
MEMORY ERASESIGNAL (MES} CONNECTOR I2PIIGRY, GRYI or IGRN, GRNI
SCS SERVICE CONNECTOR07PAZ - 0010100
3. Turn the ignition switch ON (ll),
4. The SRS indicator light comes on for about six sec-
onds and then goes off. Remove the SCS servjce con
nector from the MES connector {2P) within four sec-
onds after the SRS indicator light went otf.
5. The SRS indicator light comes on again. Reconnect
the SCS service connector to the MES connector(2P) within four seconds after the SRS indicator lioht
comes on,
6. The SRS indicator light goes otf. Remove the SCS
service connector from the MES connector (2P)
within four seconds.
7. The SRS indicator light indicates that the memory is
erased by blinking two times.
L Turn the ignition switch OFF, and wait for ten sec
onos.
SRS indicatorliqtfi
MESconnac'lolterminals
OFF
CONNECTED
OISCONNECTEO
24-28
,l sec or less
3.
Troubleshooting Intermittent
Failures
lf there was a malfunction. but it doesn't recur, it will be
stored in the memory as an intermittent failure, and the
SRS indicator light comes on.
After checking the DTC, troubleshoot as follows:
1. Read the DTC (see "Reading the DTC").
4.
Erase the DTC memory (see "Erasing the DTC
Memory").
With the shift lever in neutral, turn the ignition switch
ON (ll), and let the engine idle.
The SRS indicator ljght comes on for about six sec-
onds and then goes off.
t*F
ON
lt--- _l
Shake the wire harness and the connector, take a test
drive (quick acceleration, quick braking, cornering),
and turn the steering wheel fully left and right, and
hold it there for five to ten seconds to find the cause
of the intermittent failure.
lf the problem recurs, the SRS indicator light will
stay on.
-+t 6!.c l.-
Problem recurs, light stays on.
6. lf you can't duplicate the intermiftent tailure, the sys-
tem is OK at this time.
:-
-4
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SRS Unit
).0Replacement
CAUTION:
. Before disconnecting any part of the SRS wire har-
nesg, disconnect the airbag connoctors (and soat beh
tensioner connectorsl.
. During installation or replacament, do not bump(impact wrench, hammer etc.) the area near the SRS
unit.
Do not damage the SFS unit terminalg or connsc-
lors.
Do not disassemble the SRS unit it has no saryice-
able parts,
Store the SRS unit in a clean, dry area.
Do not use any SRS unit which has been subiected
to water damage or shows signs ot being dropped orimproperly handlgd, such as dents, cracks or defor-
mation.
Disconnect the battery negative cable, then discon-
nect the positive cable from the battery, andwaitat
least three minutes.
Disconnect the airbag connectors (and seat belt ten-
sioner connectors). (When disconnected, the airbag
and seat belt tensioner connectors are automatical-
ly shorted.)
Driver's Side:
. Remove the access panel from the steering
wheel, then disconnect the 2P connector
between the driver's airbag and cable reel (see
page 24-231.
Front Passenger's Side:. Disconnect the 2P connector between the frontpassenger's airbag and SRS main harness (see
page 24-231.
Soat Beh Tensionor ('98 - 00 modelsr:. Remove the left and right center pillar lower trimpanels (see section 20).
. Disconnect the seat belt tensioner 2P connectors
from the left side wire harness (driver's side) and
the right wire harness (front passenger's side)(see page 24'231.
2.
a
a
'1.
)
)o
24-95
3. Remove the right side cover from the SRS unit.
SRS UNIT
TORXAOLTSUse a TorxT30 bir.
COVER
Remove the left slde cover from the SRS unit. then
disconnect the SRS main harness 18P connector
from the SRS unit.
sRsHARNESS18P CONNECTOR
TORXBOLTSUs€ a TorxT30 bir.
stoECOVER
Remove the four Torx bolts from the SRS unit. then
oull out the SRS unit from the driver's side.
(cont'd)
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