1998 OPEL FRONTERA ABS

5A–11 BRAKE CONTROL SYSTEM
Data List
DisplayContentOK/NG Criteria for Data
Battery VoltageVo l t a g eBetween 10-16.9V
Brake Light SwitchOpen/CloseOpen(0V) when pedal is released
Closed(12V) when pedal is depressed.
Front Left Wheel Speed
Front Right Wheel Speed
Rear Left Wheel Speed
Rear Right Wheel SpeedMPH(km/h)Start the vehicle and make sure of linear change in each
wheel speed.
Turn each wheel by hand and make sure that each
speed data change.
Wheel Sensor StatusOK/NGTo be OK usually
G-sensorLow/HighTo be Low usually
Transfer Monitor(TOD)2 Wheel Drive
4 Wheel DriveWhen 2WD: 2 Wheel Drive
When 4WD: 4 Wheel Drive
Off-Road Switch
(Transmission Input)
Active/InactiveWhen shift lever position is 1, 2 and R: Active (M/T)
(Transmission Input)When shift lever position is L and R: Active (A/T)
Valve RelayActive/InactiveTo be Active usually
ABS StateON/OFFTo be OFF usually
ABS RelayActive/InactiveTo be Active usually
Return Pump RelayActive/InactiveTo be Inactive usually
Front Left Isolation ValveActive/InactiveTo be Inactive usually
Front Left Dump Valve
Front Right Isolation Valve
Front Right Dump Valve
Rear Isolation Valve
Rear Dump Valve
ABS Warning LampON/OFFTo be ON usually (while engine stopped)

5A–35 BRAKE CONTROL SYSTEM
Symptom Diagnosis
The symptoms that cannot be indicated by the warning
light can be divided in the following five categories:
1. ABS works frequently but vehicle does not
decelerate.
2. Uneven braking occurs while ABS works.
3. The wheels lock during braking.4. Brake pedal feel is abnormal.
5. Braking sound (from EHCU) is heard while not
braking.
These are all attributable to problems which cannot be de-
tected by EHCU self-diagnosis. Use the customer com-
plaint and a test to determine which symptom is present.
Then follow the appropriate flow chart listed below.
NoSymptomDiagnostic Flow ChartsNo.Sym tomWithout TECH 2With TECH 2
1ABS works frequently but vehicle does not decelerate.Chart A–1Chart TA–1
2Uneven braking occurs while ABS works.Chart A–2—
3The wheels are locked.Chart A–3Chart TA–3
4Brake pedal feel is abnormal.Chart A–4—
5Braking sound (from EHCU) is heard while not braking. Chart A–5Chart TA–5
Chart A–1 ABS Works Frequently But Vehicle Does Not Decelerate
StepActionYe sNo
11. Turn key off.
2. G Sensor connector and EHCU connector disconnected.
Is there continuity between EHCU terminals 26 and 8?
Go to Step 2Go to Step 3
2Connect EHCU connector.
Is there continuity between the G sensor and the EHCU?
Go to Step 3
Repair circuit.
Go to Step 1
3Is the G sensor normal? (Refer to chart B-5)
Go to Step 4
Replace G
sensor.
Go to Step 11
4Is braking force distribution normal between the front and rear of
the vehicle?
Go to Step 5
Repair brake
parts.
Go to Step 11
5Are axle parts installed normally?Go to Step 6Repair axle parts.
Go to Step 11
6Is there play in each wheel speed sensor?Repair wheel
speed sensor.
Go to Step 11
Go to Step 7
7Is there damage, or powered iron sticking to each wheel speed
sensor/sensor ring?Replace sensor
or sensor ring.
Go to Step 11
Go to Step 8
8Is the output of each wheel speed sensor normal? (Refer to chart
C-1 or TC-1)
Go to Step 9
Replace wheel
speed sensor or
repair harness.
Go to Step 11
9Is the input of transmission normal? (Refer to chart C-2 or TC-2)
Go to Step 10
Replace switch or
repair harness.
Go to Step 11

5A–36
BRAKE CONTROL SYSTEM
StepNo Ye s
Action
10Is the input of 4WD controller normal?
Go to Step 11
Replace
controller or
repair harness.
Go to Step 11
11Reconnect all components and ensure all components are
properly mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 11
Chart TA-1 ABS Works Frequently But Vehicle Does Not Decelerate (Use TECH 2)
StepActionYe sNo
11. Connect TECH 2.
2. Make sure of the output conditions of each wheel speed
sensor by mode “F1: Data Display”.
Is the output of each sensor normal?
Go to Step 2
Replace wheel
speed sensor.
Go to Step 3
2Return to Chart A-1.
Was the Chart A-1 finished?
Go to Step 3Go to Step 2
3Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 3
Chart A-2 Uneven Braking Occurs While ABS Works
StepActionYe sNo
1Is there play in each sensor?Repair.
Go to Step 5
Go to Step 2
2Is there damage or powdered iron sticking to each sensor/sensor
ring?Repair.
Go to Step 5
Go to Step 3
3Is the output of each sensor normal? (Refer to chart C-1 or TC-1)
Go to Step 4
Replace sensor
or repair harness.
Go to Step 5
4Is brake pipe connecting order correct?
Replace EHCU.
Go to Step 5
Reconnect brake
pipe correctly.
Go to Step 5
5Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 5
Chart A-3, TA-3 The Wheels Are Locked
StepActionYe sNo
1Is ABS working?Go to Step 2Go to Step 6
2Is vehicle speed under 10 km/h (6mph)?Normal.Go to Step 3
3Is sensor output normal? (Chart C-1 or TC-1)
Go to Step 4
Replace sensor
or repair harness.
Go to Step 9
4Is transmission input normal? (Chart C-2 or TC-2)
Go to Step 5
Replace SW or
repair harness.
Go to Step 9

5A–38
BRAKE CONTROL SYSTEM
Chart A-5, TA-5 Braking Sound (From EHCU) Is Heard While Not Braking
StepActionYe sNo
1Is this the first time the vehicle is being driven after starting the
engine?It is self checking
sound.
Normal.
Go to Step 2
2Is vehicle speed under 10 km/h (6 mph)?It is self checking
sound.
Normal.
Go to Step 3
3Check for the following condition:
At the time of shift down or clutch operation.
A t t h e t i m e o f l o w drive (ice or snow road) or rough road drive.
At the time of high-speed turn.
At the time of passing curb.
At the time of operating electrical equipment switches.
At the time of racing the engine (over 5000 rpm).
Did it occur under any one condition above?
ABS may
sometime be
actuated even
when brake pedal
is not applied.
Go to Step 4
4Is there play in each sensor/wheel speed sensor rings?
Go to Step 5
Repair.
Go to Step 7
5Damage or powdered iron sticking to each sensor/wheel speed
sensor ring?
Go to Step 6
Repair.
Go to Step 7
6Is each sensor output normal?(Refer to chart C-1 or TC-1).Check harness/
connector for
suspected
disconnection.
If no
disconnection is
found, replace
EHCU.
Go to Step 7
Repair.
Go to Step 7
7Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 7

5A–40
BRAKE CONTROL SYSTEM
Diagnosis By “ABS” Warning Light
Illumination Pattern
In the event that there is abnormality in the “ABS” warning
light illumination pattern while the key is in the ON position
or if the warning light is actuated during driving, trouble
should be diagnosed on a illumination pattern basis as
follows:
No.
Condition“ABS” Warning Light Illumination PatternDiagnostic
1Warning light is actu-
ated normallyNormal
2Warning light is not litWarning light lighting circuit
trouble
Go to Chart B-1
3Warning light remains
ONDiagnostic trouble codes are
stored.
Display diagnostic trouble
codes and diagnose on a
code basis according to the
flow charts.
4Warning light is actu-
ated while drivingDiagnostic trouble codes are
stored.
Display diagnostic trouble
codes and diagnose on a
code basis according to the
flow charts.
Diagnostic Trouble Codes (DTCs)
When the warning light in the meter remains ON, the
EHCU stores the fault identification and disables the
ABS.
1. How to display and erase DTCs:
NOTE:
If DTCs are not displayed, harness C-4 connector
terminal 30 and I-10 connector terminal 2 may be
disconnected. Repair the harness and try DTC
display again.
DTCs can be displayed also by TECH 2. Select mode
“F0: Diagnostic Trouble Codes” from Application
Menu.
1. How to start DTC display:
Confirm that the vehicle has come to a complete
stop (with the wheels standing still) and that the
brake pedal is not depressed. (Unless these two
conditions are satisfied, DTC display cannot be
started.)
With IGN OFF, connect #12 terminal with #4
terminal or # 5 terminal (GND) . Then turn IGN ON.

5A–42
BRAKE CONTROL SYSTEM
4. Notes
If the following should occurs during Diagnostic
Trouble Code (DTC) display the display will be
discontinued. After initial check, the status that is
under the control of ABS will be returned :
– The vehicle starts (The wheels turn) or the brake
pedal is depressed.
Up to 3 different codes can be stored.
If the ABS should turn OFF due to an intermittent
defect, the system will be restored at the next key
cycle, if the initial check finds no abnormality (when
IGN is switched from OFF to ON).
5. An example of DTC display
Display of DTC 23
B05RW006
After displaying DTC 12 three times, one DTC after
another is displayed, starting with the most recent
one. (However, display is discontinued after about 5
minutes.)
B05RS005
The DTC 12 is displayed repeatedly. (display is
discontinued after about 5 minutes)

5A–57 BRAKE CONTROL SYSTEM
Unit Inspection Procedure
This section describes the following inspection
procedures referred to during “SYMPTOM DIAGNOSIS”
and “DIAGNOSIS BY ‘ABS’ WARNING LIGHT
ILLUMINATION PATTERN” :
without TECH 2with TECH 2
Wheel Speed Sensor Output InspectionChart C-1-1 to C-1-4Chart TC-1
Transmission SW InspectionChart C-2Chart TC-2
Chart C-1-1 FL Sensor Output Inspection Procedure
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector.
3. Jack up the vehicle, With all four wheels off the ground.
Measure the AC voltage between EHCU connector terminals
while turning FL wheel at a speed of 1 RPS:
Is voltage between EHCU connector terminals 20 and 21 under
200 mV?
Go to Step 2
Ok.
Go to Step 3
21. Disconnect the wheel speed sensor.
2. Measure resistance between the wheel speed sensor
connector terminals 1 and 2.
Is resistance between connector (C-13) terminals 1 and 2 within
1.3k - 1.9k ohms?Connector is
faulty, or open or
short circuit in
harness between
wheel speed
sensor connector
and EHCU.
Inspect and
correct the
connector or
harness
Go to Step 3
Wheel speed
sensor is faulty.
Replace the
wheel speed
sensor.
Go to Step 3
3Reconnect all components and ensure all components are
properly mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 3

6A–6
ENGINE MECHANICAL
Rough Engine Idling or Engine Stalling
ConditionPossible causeCorrection
Trouble in fuel injection systemIdle air control valve defectiveReplace
Throttle shutting off incompleteCorrect or replace
Throttle position sensor circuit open
or shortedCorrect or replace
Fuel injector circuits open or shortedCorrect or replace
Fuel injectors damagedReplace
Fuel pump relay defectiveReplace
Mass Airflow Sensor circuit open or
poor connectionsCorrect or replace
Mass Airflow Sensor defectiveReplace
Manifold Absolute Pressure Sensor
circuit open or poor connectionsCorrect or replace
Manifold Absolute Pressure Sensor
defectiveReplace
Engine Coolant Temperature Sensor
circuit open or poor connectionsCorrect or replace
Engine Coolant Temperature Sensor
defectiveReplace
Intake Air Temperature sensor circuit
open or poor connectionsCorrect or replace
Intake Air Temperature sensor
defectiveReplace
Knock Sensor (KS) cable broken or
poor connectionsCorrect or replace
KS defectiveReplace
KS Module circuits open or groundCorrect or replace
KS Module defectiveReplace
Vehicle Speed Sensor circuit open or
shortedCorrect or replace
Vehicle Speed Sensor defectiveReplace
Trouble in emission control systemPowertrain Control Module defectiveReplace
Exhaust Gas Recirculation Valve
circuit open or poor connectionsCorrect or replace
Exhaust Gas Recirculation Valve
faultyReplace
Canister purge valve circuit open or
poor connectionsCorrect or replace
Canister purge valve defectiveReplace
Evaporative Emission Canister
Purge control valve defectiveReplace
Trouble in ignition systemRefer to “Hard Start”