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Opel Frontera UBS. Manual - part 2039

5A–36

BRAKE CONTROL SYSTEM

Step

Yes

Action

Is the input of 4WD controller normal?

Go to Step 11

Replace

controller or

repair harness.

Go to Step 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

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

Return to Chart A-1.

Was the Chart A-1 finished?

Go to Step 3

Go to Step 2

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

Is there play in each sensor?

Repair.

Go to Step 5

Go to Step 2

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

Repair.

Go to Step 5

Go to Step 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

Is brake pipe connecting order correct?

Replace EHCU.

Go to Step 5

Reconnect brake

pipe correctly.

Go to Step 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

Is ABS working?

Go to Step 2

Go to Step 6

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

Normal.

Go to Step 3

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

Go to Step 4

Replace sensor

or repair harness.

Go to Step 9

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

Go to Step 5

Replace SW or
repair harness.

Go to Step 9

5A–37

BRAKE CONTROL SYSTEM

Step

Yes

Action

Is front 4WD controller normal?

Replace EHCU.

Go to Step 9

Replace 4WD

controller or

repair harness.

Go to Step 9

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

Go to Step 7

Replace SW or

repair harness

Go to Step 9

Is front 4WD controller normal?

Go to Step 8

Replace 4WD

controller or

repair harness.

Go to Step 9

Is hydraulic unit grounded properly?

Replace EHCU.

Go to Step 9

Correct.

Go to Step 9

Reconnect all components, ensure all components are properly
mounted.

Was this step finished?

Repeat the “Basic

diagnostic flow

chart.”

Go to Step 9

Chart A-4 Brake Pedal Feed Is Abnormal

Step

Action

Yes

Is the stop light actuated when the brake pedal is depressed?

Go to Step 2

Go to Step 3

1. Turn the ignition switch off.
2. Disconnected EHCU connector.
3. Measure voltage between the EHCU connector terminal 10

and 15 when brake pedal is depressed.

Is the voltage equal to the battery voltage?

Go to Step 4

Harness NG

between brake

SW and EHCU.

Go to Step 7

Is stop light fuse C-14 normal?

Go to Step 5

Replace fuse

C-14.

Go to Step 7

Is there continuity between EHCU connector terminals, 12 and 15
to body ground?

Go to Step 6

Repair body

grounded

harness.

Go to Step 7

Is the brake SW normal?

Repair stop light

harness.

Go to Step 7

Replace brake

SW.

Go to Step 7

Is the check harness/connector for suspended disconnection?

Hydraulic system

leakage or air

entry (Refer to

servicing

“Leakage or

brake fluid” )

Go to Step 7

Repair harness.

Go to Step 7

Reconnect all components and ensure all components are
properly mounted.

Was this step finished?

Repeat the “Basic

diagnostic flow

chart.”

Go to Step 7

5A–38

BRAKE CONTROL SYSTEM

Chart A-5, TA-5 Braking Sound (From EHCU) Is Heard While Not Braking

Step

Action

Yes

Is this the first time the vehicle is being driven after starting the
engine?

It is self checking

sound.

Normal.

Go to Step 2

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

It is self checking

sound.

Normal.

Go to Step 3

Check for the following condition:

At the time of shift down or clutch operation.

At the time of low

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

Is there play in each sensor/wheel speed sensor rings?

Go to Step 5

Repair.

Go to Step 7

Damage or powdered iron sticking to each sensor/wheel speed
sensor ring?

Go to Step 6

Repair.

Go to Step 7

Is 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

Reconnect all components, ensure all components are properly
mounted.

Was this step finished?

Repeat the “Basic

diagnostic flow

chart.”

Go to Step 7

5A–39

BRAKE CONTROL SYSTEM

Diagnostic Trouble Codes

Choose and trace an appropriate flowchart by the
numbers listed below to find fault and repair.

Code

Item

Diagnosis

Chart No.

Start Code

Normal

—

EHCU Function

Abnormality in input/output, operational and
control circuits

B-2

Power Voltage Drop

B-3

CLASS–2 Communication Line Ab-
normality

B-4

G-sensor

Wiring disconnection

B-5

Transmission Input

Input abnormality

B-6

Transfer Monitor

B-7

Motor & Motor Relay

Shorted or disconnected coil

B-8

Valve Relay