warning OPEL FRONTERA 1998 Owner's Manual

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–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–41 BRAKE CONTROL SYSTEM
The DLC is located behind the center console
350RV010
Keep #12 terminal connected with #4 terminal or # 5
terminal (GND) during DTC display. (If #12 terminal
is separated from #4 terminal or # 5 terminal (GND)
during display, display will stop.)
2. DTC display:
DTC is displayed by blinking warning light.
Double-digit display.
First, normal DTC 12 is displayed three times and
then any other DTCs are displayed three times. (If
no other DTCs have been stored, the display of DTC
12 will be repeated.)
3. How to erase code:
Conduct brake switch ON/OFF operation 6 or more
times within 3 seconds of self-diagnosis startup.
The code cannot be erased if more than 3 seconds
have passed since self-diagnosis startup, or if
self-diagnosis has started with brake switched on
(brake pedal depressed).
B05RW005

5A–43 BRAKE CONTROL SYSTEM
Chart B-1 With the key in the ON position (Before starting the engine). Warning light (W/L)
is not activated.
StepActionYe sNo
1Is W/L fuse C-10 disconnected?Replace fuse.
Go to Step 5
Go to Step 2
2Is W/L burnt out?Replace W/L
bulb.
Go to Step 5
Go to Step 3
31. Turn the key off.
2. Disconnect EHCU connector.
3. Turn the key ON.
4. Measure the voltage between EHCU connector terminal 13
and 14.
Is the voltage equal to the battery voltage?
Go to Step 4
Repair harness
and connector.
Go to Step 5
4Is there continuity between EHCU connector terminals, 12 and 15
and body ground.Check harness
for suspected
disconnection.
No fault found:
Replace EHCU.
Go to Step 5
Repair harness
and connector.
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 B-2 EHCU Abnormality (DTC 14)
StepActionYe sNo
11. Turn the key off.
2. Disconnect the EHCU connector.
3. Inspect EHCU ground.
Is there resistance between the EHCU connector terminals, 12
and 15 and body ground?
Go to Step 2
Repair the body
ground harness.
Go to Step 3
21. Turn the key off, connect the EHCU.
2. Erase the trouble code.
3. Turn Ignition off, then on, to perform system self-check.
4. If warning light remains on, display trouble codes once again.
Is the check trouble code 14?
Replace EHCU.
Go to Step 3
Inspect in
accordance with
the DTC
displayed.
31. Reconnect all components and ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the “Basic
diagnostic flow
chart.”
Go to Step 3

5A–52
BRAKE CONTROL SYSTEM
Chart B-20 FL Speed Sensor Short Circuit (DTC 61)
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector
3. Measure the FL speed sensor resistance between EHCU
connector terminals 20 and 21.
Is the resistance between 1.3k and 1.9k ohms?
Go to Step 2Go to Step 3
2Is there play in the sensor/sensor rotor?
Go to Step 4
Repair.
Go to Step 6
3Measure the FL speed sensor resistance at the sensor connector.
Is the resistance between 1.3k and 1.9k ohms?Repair harness
abnormality
between sensors
and EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
4Damage and powdered iron sticking to sensor/sensor ring?
Go to Step 5
Repair.
Go to Step 6
5Is sensor output normal? (Chart C-1-1 or TC-1)Check for faults
in harness
between speed
sensor and
EHCU.
Fault found:
repair, and
perform system
self-check.
No fault found:
replace EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
61. Reconnect all components and ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the “Basic
diagnostic flow
chart.”
Go to Step 6
NOTE: Even after repairing the faulty part the warning
light (W/L) does not go out if the vehicle is at a stop. Turn
the ignition switch to the ON position and drive the vehicle
at 12 km/h or higher to make sure that the warning light
goes out.

5A–53 BRAKE CONTROL SYSTEM
Chart B-21 FR Speed Sensor Short Circuit (DTC 62)
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector.
3. Measure the FR speed sensor resistance between EHCU
connector terminals 4 and 5.
Is the resistance between 1.3k and 1.9k ohms?
Go to Step 2Go to Step 3
2Is there play in the sensor/sensor rotor?
Go to Step 4
Repair.
Go to Step 6
3Measure the FR speed sensor resistance at the sensor
connector.
Is the resistance between 1.3k and 1.9k ohms?Repair harness
abnormality
between sensors
and EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
4Damage and powdered iron sticking to sensor/sensor ring?
Go to Step 5
Repair.
Go to Step 6
5Is sensor output normal? (Chart C-1-2 or TC-1)Check for faults
in harness
between speed
sensor and
EHCU.
Fault found:
repair, and
perform system
self-check.
No fault found:
replace EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
61. Reconnect all components and ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat “Basic
diagnostic flow
chart.”
Go to Step 6
NOTE: Even after repairing the faulty part the warning
light (W/L) does not go out if the vehicle is at a stop. Turn
the ignition switch to the ON position and drive the vehicle
at 12 km/h or higher to make sure that the warning light
goes out.

5A–54
BRAKE CONTROL SYSTEM
Chart B-22 RL Speed Sensor Short Circuit (DTC 63)
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector
3. Measure the RL speed sensor resistance between EHCU
connector terminals 22 and 23.
Is the resistance between 1.3k and 1.9k ohms?
Go to Step 2Go to Step 3
2Is there play in the sensor/sensor rotor?
Go to Step 4
Repair.
Go to Step 6
3Measure the RL speed sensor resistance at the sensor
connector.
Is the resistance between 1.3k and 1.9k ohms?Repair harness
abnormality
between sensors
and EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
4Damage and powdered iron sticking to sensor/sensor ring?
Go to Step 5
Repair.
Go to Step 6
5Is sensor output normal? (Chart C-1-3 or TC-1)?Check for faults
in harness
between speed
sensor and
EHCU.
Fault found:
repair, and
perform system
self-check.
No fault found:
replace EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
61. Reconnect all components and ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the “Basic
diagnostic flow
chart.”
Go to Step 6
NOTE: Even after repairing the faulty part the warning
light (W/L) does not go out if the vehicle is at a stop. Turn
the ignition switch to the ON position and drive the vehicle
at 12 km/h or higher to make sure that the warning light
goes out.

5A–55 BRAKE CONTROL SYSTEM
Chart B-23 RR Speed Sensor Short Circuit (DTC 64)
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector.
3. Measure the RR speed sensor resistance between EHCU
connector terminals 2 and 3.
Is the resistance between 1.3k and 1.9k ohms?
Go to Step 2Go to Step 3
2Is there play in the sensor/sensor rotor?
Go to Step 4
Repair.
Go to Step 6
3Measure the RR speed sensor resistance at the sensor
connector.
Is the resistance between 1.3k and 1.9k ohms?Repair harness
abnormality
between sensors
and EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
4Damage and powdered iron sticking to sensor/sensor ring?
Go to Step 5
Repair.
Go to Step 6
5Is sensor output normal? (Chart C-1-4 or TC-1)Check for faults
in harness
between speed
sensor and
EHCU.
Fault found:
repair, and
perform system
self-check.
No fault found:
replace EHCU.
Go to Step 6
Replace sensor.
Go to Step 6
61. Reconnect all components and ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat “Basic
diagnostic flow
chart.”
Go to Step 6
NOTE: Even after repairing the faulty part the warning
light (W/L) does not go out if the vehicle is at a stop. Turn
the ignition switch to the ON position and drive the vehicle
at 12 km/h or higher to make sure that the warning light
goes out.

5A–56
BRAKE CONTROL SYSTEM
Chart B-24 Sensor Signal Input Abnormality (DTC 65)
StepActionYe sNo
1Using TECH 2?Go to Step 2Go to Step 3
21. Connect TECH 2.
2. Select Snap shot manual trigger.
3. With wheel speed data displayed, run the vehicle when speed
has arrived at 30 km/h (18 mph).
4. Check speed data on each wheel (refer to the criterion given
below). *1
Is the abnormal sensor condition found?
Replace.
Go to Step 8
Go to Step 3
All the sensors
should follow the
following
flowchart (without
using TECH 2).
3Is there play in sensor/sensor ring?Repair.
Go to Step 8
Go to Step 4
4Is there powdered iron sticking to sensor/sensor ring?Repair.
Go to Step 8
Go to Step 5
5Is there a broken tooth or indentation in sensor ring?Replace sensor
ring.
Go to Step 8
Go to Step 6
6Is there play in wheel bearing?Adjust or repair.
Go to Step 8
Go to Step 7
7Is the check wiring between sensor and EHCU normal?
Replace EHCU.
Go to Step 8
Repair, and
perform system
self-check.
Go to Step 8
81. Reconnect all components, ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat “Basic
diagnostic flow
chart.”
Go to Step 8
Sensor Signal Abnormality Criteria using
TECH 2
1. While driving, the speed of one or two wheels 25% or
more higher than that of the other wheels.
2. The speed of one or two wheels is 10 km/h (6 mph) or
more higher than that of the other wheels.
3. During steady driving, wheel speed changes abruptly.
*1 The vehicle must run on a level paved road.
NOTE: Even after repairing the faulty part the warning
light (W/L) does not go out if the vehicle is at a stop.
Turn the ignition switch to the ON position and drive the
vehicle at 12 km/h or higher to make sure that the warning
light goes out.
It is important to verify that the correct tires are installed
on vehicle.

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