Opel Frontera UBS. Manual - part 1090

5A–33

BRAKE CONTROL SYSTEM

5A–34

BRAKE CONTROL SYSTEM

Part Location (RHD model)

D08RW623

Legend

(1) F–2
(2) F–3
(3) H–33
(4) H–7
(5) H–46
(6) C–16
(7) E–42, E–43, M–8
(8) E–47, E–48, M–1
(9) B–13 or B–14

(10) C–13

(11) H–4, H–5, H–6

(12) H–10, H–11
(13) E–4 (4JX1)

(14) E–30 (4GJ2, 6VD1/6VE1)
(15) Fuse Box
(16) H–42
(17) C–41
(18) C–85
(19) C–4 (EHCU)
(20) Relay & Fuse Box
(21) C–39
(22) H–13, H–15, H–16, H–26, H–27
(23) I–10
(24) I–9
(25) H–12
(26) C–63
(27) B–25

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.

No

Symptom

Diagnostic Flow Charts

No.

Sym tom

Without TECH 2

With TECH 2

1

ABS works frequently but vehicle does not decelerate.

Chart A–1

Chart TA–1

2

Uneven braking occurs while ABS works.

Chart A–2

—

3

The wheels are locked.

Chart A–3

Chart TA–3

4

Brake pedal feel is abnormal.

Chart A–4

—

5

Braking sound (from EHCU) is heard while not braking. 

Chart A–5

Chart TA–5

Chart A–1 ABS Works Frequently But Vehicle Does Not Decelerate

Step

Action

Yes

No

1

1. Turn key off.
2. G Sensor connector and EHCU connector disconnected.

Is there continuity between EHCU terminals 26 and 8?

Go to Step 2

Go to Step 3

2

Connect EHCU connector.

Is there continuity between the G sensor and the EHCU?

Go to Step 3

Repair circuit.

Go to Step 1

3

Is the G sensor normal? (Refer to chart B-5)

Go to Step 4

Replace G

sensor.

Go to Step 11

4

Is braking force distribution normal between the front and rear of
the vehicle?

Go to Step 5

Repair brake

parts.

Go to Step 11

5

Are axle parts installed normally?

Go to Step 6

Repair axle parts.

Go to Step 11

6

Is there play in each wheel speed sensor?

Repair wheel

speed sensor.

Go to Step 11

Go to Step 7

7

Is 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

8

Is 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

9

Is 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

Step

No

Yes

Action

10

Is the input of 4WD controller normal?

Go to Step 11

Replace

controller or

repair harness.

Go to Step 11

11

Reconnect 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)

Step

Action

Yes

No

1

1. 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

2

Return to Chart A-1.

Was the Chart A-1 finished?

Go to Step 3

Go to Step 2

3

Reconnect 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

Step

Action

Yes

No

1

Is there play in each sensor?

Repair.

Go to Step 5

Go to Step 2

2

Is there damage or powdered iron sticking to each sensor/sensor
ring?

Repair.

Go to Step 5

Go to Step 3

3

Is 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

4

Is brake pipe connecting order correct?

Replace EHCU.

Go to Step 5

Reconnect brake

pipe correctly.

Go to Step 5

5

Reconnect 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

Step

Action

Yes

No

1

Is ABS working?

Go to Step 2

Go to Step 6

2

Is vehicle speed under 10 km/h (6mph)?

Normal.

Go to Step 3

3

Is sensor output normal? (Chart C-1 or TC-1)

Go to Step 4

Replace sensor

or repair harness.

Go to Step 9

4

Is transmission input normal?  (Chart C-2 or TC-2)

Go to Step 5

Replace SW or
repair harness.

Go to Step 9