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
DTC 51 - 53: ABS Pump Motor (cont'dl
(From page 19 49)
UND€R-HOOO ABSFUSE/REI-AY BOX
MOTOR +B IREDIMOTOR GND IBLKI
TERMINAL TERMINAL
PUMP MOTOR CONNECTOB
Fr MOTOR +B {WHTI12 lF-(v)vI
Terminal side of female terminals
Terminalside ofmaleterminals
ABS CONTROL UNIT 22P CONNECTOR
JUMPER WIRE
Wire side of female terminals
Chock the pump motor ci.cuit:1. Remove the pump motor relay.2. Turn the ignition switch ON {ll).3. Connect the pump motor relayconnector +B and MOTOR ter-minals with a jumpor wire fora moment,
Check for an open in the pump
motor +B circuit:1. Turn the ignition switch OFF.2. Disconnect the pump motor
3. Turn the ignition switch ON (ll).
4. Connect the pump motor relayconnector +B and MOTOR terminals with a iumper wire.5. Measure the voltage beaveenthe pump motor connectorterminal No. l and bodygrou nd.
Does the pump motor operate?
Bepair opon in the wire botweenthe under-hood ABS fuse/relavbor and the pump motor.ls there battery voltage?
Check the pump motor opera-tion:Connect the battery (+)terminal tothe pump motor connector termi-nal No. 1, and the (-) terminal tothe terminal No. 2 for a moment.
Reolace the modulator unit.
lFaulty pump moto.lDoes the pump motor operate?
Ch6ck for a short to body groundin the PMR circuit:1. Turn the ignition switch OFF.2. Disconnect the ABS controlunit 22P connector.3. Check tor continuity betweenterminal No. 19 and bodyground.
Repair open in the wire bstweenthe pump motor and body ground,
or poo. ground {G3511.
Repair short to body ground inthe wir6 botween the under-hood ABS tuse/rclay box and th€ABS contlol unit.
{To page 19-51)
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