1998 OPEL FRONTERA Front ach

TRANSFER CASE (STANDARD TYPE)
4D1–39
14. Assemble the 2WD–4WD clutch hub and sleeve
assembly (7).
226RW140
15. Engage the springs in the same insert with the open
ends away from each other. (Shift On The Fly model)
226RW141
16. Place the snap ring (2), a new stopper plate (6) (Shift
On The Fly model) and the clutch sleeve and hub
assembly (7) on the front output shaft (5).
226RW135
Legend
(6) Front Output Gear
17. The clutch hub face (with the heavy boss) must be
facing the front output gear side.
18. Use a bench press to slowly force the clutch hub and
sleeve assembly (7) together with the stopper plate
(6) (Shift On The Fly model) into place.
19. Align the inserts with the block ring insert grooves.
Install the block ring (8) (Shift On The Fly model) to
the clutch sleeve and hub assembly (7).
20. Install the outside ring (9) (Shift On The Fly model),
inside ring (10) (Shift On The Fly model) and needle
bearing (12) to the front output gear (11) and bearing
collar (17).
NOTE: Coat all parts with transmission oil before
installing them.
226RW139

TRANSFER CASE (STANDARD TYPE)
4D1–41
27. Use a pair of snap ring pliers to install the snap ring
(19) to the output shaft (5).
Sub gear (anti lash plate) preload (M/T)
1. Hook a length of piano wire (4) over one of the
sub–gear (5) teeth.
2. Attach the other end of the piano wire to (4) a
spring balancer.
3. Measure the sub–gear preload.
Preload: 59–98 N (6.0–10.0kg/13–22 lb)
(M/T)
226RS075
28. Install front output gear assembly (3) to the transfer
case (1).
29. Use a pair of snap ring pliers to install the snap ring (2)
to the transfer case (1).
NOTE: The snap ring must be fully inserted into the
transfer case snap ring groove.
30. Use a bench press to install the ball bearing (32) to the
input shaft (31).
265RS003
31. Install the plate (34), ball (35), and bearing collar (36)
and place the snap ring (33).
32. Install the needle bearing (37) and input gear (38).
33. The clutch hub face (with the heavy boss) must be
facing the transfer input gear side (7).
226RW136
34. Install the high–low clutch hub and sleeve (39), using
a bench press.
35. Install the input shaft assembly (30) to the transfer
case (1).
36. Install the snap ring (33) to the transfer case (1).
NOTE: The snap ring must be fully inserted into the
transfer case snap ring groove.
37. Install the front companion flange temporarily and use
the flange holder 5–8840–0133–0 (J–8614–11) and
lock nut wrench 5–8840–2156–0 (J–37219) to install
the lock nut (40).
Torque: 137 Nꞏm (14.0kgꞏm/101 lb ft)
226RW190
38. Use the punch to stake the lock nut (40) at one spot.

4D2–15 TRANSFER CASE (TOD)
4. Apply a thin coat of grease to the seal ring of each
front and rear speed sensor, and mount the sensors
carefully.
5. Tighten the bolts to the specified torque.
Torque : 5 Nꞏm (0.5 kgꞏm/43 lb in)
NOTE: Pay attention not to mount the front (or rear)
sensor to the rear (or front) sensor position.
6. Install the ball bearing (1) for the front output shaft as
flat as shown in the figure.
261RW008
7. Mount the coil assembly and tighten the nuts to the
specified torque.
Torque : 10 Nꞏm (1.0 kgꞏm/87 lb in)
8. Connect the terminal in the central connector.
NOTE: Be careful not to damage other terminals.
9. Install speed gear and tone wheel.
10. Mount the ball bearing (2) as flat as shown in the
figure.
261RW009–1
11. Using snap ring pliers, install the snap ring to the
transfer cover assembly.NOTE: Securely install the snap ring to the groove of the
transfer cover assembly.

4D2–35 TRANSFER CASE (TOD)
2. Mount the front output shaft to the transfer case.
266RW012
3. Install the shifter lever shaft.
4. Install the snap ring.
5. Install the reduction lever assembly to the shifter lever
shaft and fix the assembly with the snap ring.
261RW021
6. Install the cam to the cam pilot block.
7. Attach the washer to the cam pilot block and fix the
washer with the snap ring.
261RW029
8. Mount the reduction fork to the lock-up shaft.
9. Install the spring pin to the reduction fork and lock-up
roll.
261RW020

5A–3 BRAKE CONTROL SYSTEM
General Description
The Anti-lock Brake System (ABS) works on all four
wheels. A combination of wheel speed sensor and
Electronic Hydraulic Control Unit (EHCU) can determine
when a wheel is about to stop turning and adjust brake
pressure to maintain best braking.This system helps the driver maintain greater control of
the vehicle under heavy braking conditions.
C05RW027
Legend
(1) With P&B Valve Model
(2) With LSPV Model
(3) Electronic Hydraulic Control Unit (EHCU)
(4) Front Wheel Speed Sensor
(5) Rear Wheel Speed Sensor(6) G-Sensor
(7) Proportioning and Bypass (P&B) Valve
(8) Load Sensing Proportioning Valve (LSPV)
(9) Electronic Line
(10) Hydraulic Line
System Components
Electronic Hydraulic Control Unit (EHCU), four Wheel
Speed Sensors, Warning Light, and G-sensor.
Electronic Hydraulic Control Unit (EHCU)
T h e E H C U c o n s i s t s o f A B S c o n t r o l c i r c u i t s , f a u l t d e t e c t o r,
and a fail-safe. It drives the hydraulic unit according to the
signal from each sensor, cancelling ABS to return to

5A–4
BRAKE CONTROL SYSTEM
normal braking when a malfunction has occurred in the
ABS.
The EHCU has a self-diagnosing function which can
indicate faulty circuits during diagnosis.
The EHCU is mounted on the engine compartment front
right side. It consists of a Motor, Plunger Pump, Solenoid
Valves and Check Valve.
On the outside, the relay box containing a motor relay and
a valve relay is installed.
Solenoid Valves: Reduces or holds the caliper fluid
pressure for each front disc brake or both rear disc brakes
according to the signal sent from the EHCU.
Reservoir: Temporarily holds the brake fluid that returns
from the front and rear disc brake caliper so that pressure
of front disc brake caliper can be reduced smoothly.
Plunger Pump: Feeds the brake fluid held in the reservoir
to the master cylinder.
Motor: Drives the pump according to the signal from
EHCU.
Check Valve: Controls the brake fluid flow.
ABS Warning Light
821RW033Vehicles equipped with the Anti-lock Brake System have
an amber “ABS” warning light in the instrument panel.
The “ABS” warning light will illuminate if a malfunction in
the Anti-lock Brake System is detected by the Electronic
Hydraulic Control Unit (EHCU). In case of an electronic
malfunction, the EHCU will turn “ON” the “ABS” warning
light and disable the Anti-lock braking function.
The “ABS” light will turn “ON” for approximately three
seconds after the ignition switch is to the “ON” position.
If the “ABS” light stays “ON” after the ignition switch is the
“ON” position, or comes “ON” and stays “ON” while
driving, the Anti-lock Brake System should be inspected
for a malfunction according to the diagnosis procedure.
Wheel Speed Sensor
It consists of a sensor and a rotor. The sensor is attached
to the knuckle on the front wheels and to the axle shaft
bearing holder on the rear wheels.
The rotor is press-fit in the axle shaft.The flux generated from electrodes magnetized by a
magnet in the sensor varies due to rotation of the rotor,
and the electromagnetic induction generates alternating
voltage in the coil. This voltage draws a “sine curve” with
the frequency proportional to rotor speed and it allows
detection of wheel speed.
G-Sensor
The G-sensor installed inside the center console detects
the vehicle deceleration speed and sends a signal to the
EHCU. In 4WD operation, all four wheels may be
decelerated in almost the same phase, since all wheels
are connected mechanically.
This tendency is noticeable particularly on roads with low
friction coefficient, and the ABS control is adversely
affected.
The G-sensor judges whether the friction coefficient of
road surface is low or high, and changes the EHCU’s
operating system to ensure ABS control.
Normal and Anti-lock Braking
Under normal driving conditions, the Anti-lock Brake
System functions the same as a standard power assisted
brake system. However, with the detection of wheel
lock-up, a slight bump or kick-back will be felt in the brake
pedal. This pedal “bump” will be followed by a series of
short pedal pulsations which occurs in rapid succession.
The brake pedal pulsation will continue until there is no
longer a need for the anti-lock function or until the vehicle
is stopped. A slight ticking or popping noise may be heard
during brake applications when the Anti-lock features is
being used.
When the Anti-lock feature is being used, the brake pedal
may rise even as the brakes are being applied. This is
also normal. Maintaining a constant force on the pedal
will provide the shortest stopping distance.
Brake Pedal Travel
Vehicles equipped with the Anti-lock Brake System may
be stopped by applying normal force to the brake pedal.
Although there is no need to push the pedal beyond the
point where it stops or holds the vehicle, by applying more
force the pedal will continue to travel toward the floor.
This extra brake pedal travel is normal.
Acronyms and Abbreviations
Several acronyms and abbreviations are commonly used
throughout this section:
ABS
Anti-lock Brake System
CKT
Circuit
DLC
Data Link Connector
EHCU
Electronic Hydraulic Control Unit
FL
Front Left

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