2003 HONDA CIVIC Control

ABS Gomponents
(Component Location Index
UNDER.HOOD FUSE/RELAY BOX
RIGHT-REAR WHEEL SENSORInspection, page 19-59Replacement, page 19-59UNDER.OASH FUSE/RELAY BOX
\L
LEFT.REARWHEEL SENSORInspection, page 19-59Replacement, page 19-59
DATA LINK CONNECTOR I16PIRIGHT.FRONT WHEEL SENSORInspection, page 19-59Replacement, page 19-59
ABS MODULATOR.CONTROL UNITRemoval and Installation, page 19'57LEFT-FRONT WHEEL SENSORInspection, page 19-59Replacement, page 19 59
19-30

General Troubleshooting Information
ABS Indicator
. lf the system is OK,theABS indicator goes off 2
seconds after turning the ignition switch ON (ll)
without starting the engine, and then comes on again
and goes off 2 seconds later after starting the engine.
This occurs because the ABS control unitisturned
on by the lG2 power source.. The ABS indicator comes on when the ABS control
unit detects a problem in the system. However, even
though the system is operating properly, the indicator
will come on under these conditions:- Only the drive wheels rotate- One drive wheel is stuck- The vehicle goes into a spin- The ABS continues to operate for a long time.- The vehicle is subjected to an electrical signal
disturbance
To determine the actual cause of the problem, question
the customer about the problem. taking the above
condilions into consideration.
. When a Droblem is detected and lhe ABS indicator
comes on, there are cases when the indicator stays
on until the ignition switch is turned OFF, and cases
when the indicator goes off automatically when the
sYstem returns to normal.- DTC 61: The ABS indicator goes off automatically
when the system returns to normal.- DTC 11, 13,15,17 ,31,32,33, 34, 35, 36, 37, 38, 54,
or 81: The ABS indicator stays on until the ignition
switch is turned OFF whether or not the system
returns to normal.- DfC 12, 14, 16, 1a,21,51,52, or 53; The ABS
indicator goes off when the vehicle is driven again
and the system is OK after the ignition switch is
turned from OFF to ON {ll}.
Diagnostic Trouble Code {DTCI
. The memory can hold three DTCS. However, when
the same DTC is detected more than once, the more
recent DTC is written over the earlier one.
Therefore, when the same problem is detected
repeatedly, it is memorized as a single DTC.. The DTCs are in the order they occurred, beginning
with the most recent.. The DTCS are memorized in the EEPROM (non-
volatile memory). Therefore. the memorized DTCs
are not cleared when the battery is disconnected, the
ignition switch is turned off, or the system returns to
normal. Do the specified procedures to clear the
DTCs.
Self-diagnosis
. Self-diagnosis can be classified into two categories:- Initial diagnosis:
Done right after the engine starts and until the ABS
indicator goes off- Regular diagnosis:
Done rightafterthe initial diagnosis until the
ignition switch is turned OFF. When a problem is detected by self-diagnosis, the
system does the following:- Turns the ABS indicator on- Memorizes the DTC- Stops ABS control
Kickback
The pump 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
. The pump motor operates when the ABS is
functioning.. The ABS control unit checks the pump motor
operation when the vehicle is started the first time
after the ignition switch is turned ON (ll). You may
hear the motor operate at this time, but it is normal.
(cont'd)
19-31

ABS Components
General Troubleshooting Information (cont'd)
How to Troubleshoot ABS DTCs
The troubleshooting flowchart procedures assume that
the cause of the oroblem is still Dresent and the ABS
indicator is still on. Following the flowchart when the
ABS indicator does not come on can result in incorrect
diagnosis.
The connector illustrations show the female terminal
connectors with a single outline and the male terminal
connectors with a double outline.
1. Ouestion the customer about the conditions when
the problem occured, and try to reproduce the
same conditions for troubleshooting. Find out
when the ABS indicator came on, such as during
ABS control, after ABS control, when the vehicle
was at a certain speed, etc.
2. When the ABS indicator does not come on during
the test-drive, but troubleshooting is done based on
the DTC, check for loose connectors. poor terminal
contact, etc., before you start troubleshooting.
3. After troubleshooting, clear the DTC,disconnect the
Honda PGM Tester. and test-drive the vehicle.
Make sure the ABS indicator does not come on.
How to Retrieve ABS DTCs
Honda PGM Tester Method:
1, Wjth the ignition switch OFF, connect the Honda
PGM Tester (A) to the 16P data link connector (DLC)
(B) under the driver's side of the dashboard.
19-32
2. Turn the ignition switch ON (ll), and follow the
prompts on the PGM Tester to display the DTC{S)
on the screen. After determining the DTC, refer to
the DTC Troubleshooting Index.
NOTE: See the Honda PGM Tester user's manual
for specific instructions.
Service Check Signal (SCS) Circuit Method:
1. With the ignition switch OFF, connect the Honda
PGM Tester (A) to the 16P data link connector (DLC)
(BI under the driver's side of the dashboard.
2. Short the SCS circuit to body ground using the
Honda PGM Tester.
3. Turn the ignition switch ON (ll).

ABS Gomponents
System Description
ABS Control Unit Inputs and Outputs for 31P Connector
Wire side of temale terminals
124567BI11121415
16111B19
20?1/t/t/l/t/
Terminal
number
Wire
color
Terminal signDescriptionMeasurement
TerminalsConditions llgnition
switch ON (ll))Voltage
BLU/
YEL
RRSDetects righfrear
wneetsensor
srgnal
;a-_-l
6-7
Wheel
Spin wheelat
I turn/second
AC: 0.053 V or
above
Oscilloscope
0.15 Vp-p or
above
GRN/
YEL
RRS (+)
BLUFRS (-)Detects right-front
wneetsensor
srgnal
5GRN/
BLK
FRS (+)
6BRN/
WHT
FLS (_)Detects left-front
wneet sensor
srgnal7BLU/
ORN
FLS {+)
8GRY/
RED
RLS HDetects left-rear
wneetsensor
srgnal
89
9YEU
RED
RLS (+)
11LT BLUDIAG KCommunications
with Honda PGM
rester
12BRNDIAG LDTC indication
19-36

ABS Gomponents
System Description (cont'd)
Features
When the brake pedal is pressed during driving, the wheels can lock before the vehicle comes to a stop. In such an
event. the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is
reduced if the rear wheels are locked, creating an extremely unstable condition. The ABS precisely controls the slip
rate of the wheels to ensure maximum grip force from the tires, thereby ensuring the maneuverability and stability of
the vehicle.
The ABS calculates the slip rate of the wheels based on the vehicle speed and the wheel speed, then it controls the
brake fluid pressure to reach the target slip rate.
Grip Force of Tire and Road Surface
TARGET SLIP RATE
COEFFICIENT OFFRICTION
SLIP RATE
19-38

ABS Control Unit
Main 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 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 intensifying.
Self-diagnosis Function
1. TheABScontrol unitisequippedwithamainCPUandasub-CPU.EachCPUcheckstheotherforproblems.
2. The CPUS check the circuit of the system.
3. TheABScontrol unitturns ontheABS ind icator when the unitdetectsa problem andthe unit stops th e system.
4. The self-diagnosis can be classified into these two categories:. lnitial diagnosis. Regular diagnosis
On-board Diagnosis Function
The ABS 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
PGM Tester. See the Honda PGM Tester user's manual for specific operating instructions.
(cont'd)
T---
19-39

ABS Components
System Description (cont'd)
ABS Modulator
The ABS modulator consists of the inlet solenoid valves, outlet solenoid valves, reservoir, pump, pump motor, and the
damping chamber. The modulator reduces the caliper fluid pressure directly. lt is a circulating-type modulator
becausethe brakefluidcirculatesthroughthecaliper,reservoir,andthemastercylinder.Thehydrauliccontrol has
three modes: pressure intensifying, pressure retaining, and pressure reducing. The hydraulic circuit is an independent
four-channeltype, one channel for each wheel.
Pressure intensifying mode: Inletvalve open, outlel valve closed
Master cylinder fluid is pumped out to the caliper.
Pressure retaining mode: lnlet valve closed, outlet valve closed
Caliper fluid is retained by the inlet valve and outlet valve.
Pressure reducing mode: Inlet valve closed, outlet valve open
Caliper fluid flows through the outlet valve to the reservoir.
lvlotor operation mode: When starting the pressure reducing mode, the pump motor is ON.
When stopping ABS operation, the pump motor is OFF.
The caliper fluid is pumped out by the pump, through the damping chamber, to the
master cvlinder.
19-40

t
Wheel Sensors
The wheel sensors are the magnetic contactless type. As the gear pulser teeth rotate past the wheel sensor's magnetic
coil, AC current is generated. The AC frequency changes in accordance with the wheel speed. The ABS control unit
detects the wheel sensor signal frequency and thereby detects the wheel speed.
!t LOW SPEED
Wheel Speed and Modulator Control
8E!EEETqE VEJ!q!ESPEEq
5
PRESSURE
OUTLETVALVE 9p
OFF
INLETVALVE oN
OFF
MoroR I-,. ltlOFF
When the wheel speed drops sharply below the vehicle speed, the inlet valve closes and il necessary, the outlet valve
opens momentarily to reduce the caliper fluid pressure. The pump motor starts at this time. As the wheel speed is
restored, and the outlet valve closes, the inlet valve opens momentarily to increase the caliper fluid pressure.
GEAR PULSERWHEEL S€NSOR.r HIGX SPEED
19-41