1999 SUZUKI GRAND VITARA Front differential

YH4
GRAND
VITARA
AUTOMATIC TRANSMISSION (4 A / T) 7B1-65
1. Drain plug
2. Propeller shaft
1. Oiler (with transmission fluid)
2. Solenoid valve
3. BatteryA: Hole (Should be dry)
B: Exhausting fluid Terminal Arrangement of PCM Coupler
(Viewed from harness side)
WITH BATTERY VOLTAGE WITHOUT BATTERY VOLTAGE
H25 Engine
Shift solenoid valve ± A (#1)C51-1-6
Shift solenoid valve ± B (#2)C51-1-1
TCC (Lock-up) solenoid valveC51-1-2
REMOVAL
1) Pull out dipstick and lift up vehicle.
2) With engine cooled, remove drain plug from oil pan and drain
A / T fluid.
3) Install drain plug with gasket.
Tightening Torque
(a): 23 N
.m (2.3 kg-m, 17.0 lb-ft)
4) Remove exhaust pipe bracket and disconnect front propeller
shaft from front differential (if equipped).
5) Remove oil pan bolts.
6) Remove oil pan.
7) Remove oil tubes.
8) Remove solenoid valve No.1 (shift solenoid valve A and B) or so-
lenoid valve No.2 (TCC solenoid valve).
OPERATION CHECK
Whenever shift solenoid valves and TCC (lock-up) solenoid valve
are removed from transmission, verify their valve function physical-
ly before they are reinstalled.
1) Apply oiler to solenoid valve and give compression by hands
and then check to be sure that transmission fluid from oiler does
not come out of holes in solenoid valve when battery voltage is
not conducted.
2) Under the same conditions as above, conduct battery voltage
and then make sure that fluid comes out with vigor.
NOTE:

If fluid does not come out with vigor in above step 2 in-
spection, do not re-use that solenoid valve.

Figure at the left shows shift solenoid valve check.
Check TCC solenoid valve also in the same way.

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GRAND
VITARA
7D-2 TRANSFER
DIAGNOSIS
DIAGNOSIS TABLE
Before attempting to repair the transfer or related components for any reason other than mechanical failure, the
condition and probable causes should be identified.
Transfer failures are revealed by shifting difficulties such as excessive shifting effort, gear clash, or gear grinding.
When any of these conditions occur, the following inspections should be made before disassembling the transfer.
1) Check transfer oil level for insufficient or incorrect oil. Refer to ªTransfer and Differential Oil Inspection and
Changeº in SECTION 0B ªMAINTENANCE AND LUBRICATIONº.
2) Check transfer mountings for wear or looseness.
3) Check gearshift control lever for distortion or excessive wear.
After performing the above inspections, refer to following diagnosis table.
Condition
Possible CauseCorrection
Gear slipping out of mesh
Worn shift fork shaft

Worn shift fork or synchronizer sleeve

Weak or damaged locating spring

Worn bearings on output rear shaft

Worn chamfered tooth on sleeve or gear

Missing or disengagement of circlip(s)Replace
Replace
Replace
Replace
Replace sleeve and gear
Install
Gears refusing to disengage
Weakened or broken synchronizer spring

Distorted shift shaft or shift forkReplace
Replace
Hard shifting
Weakened front drive shift shaft spring

Distorted or mispositioned front drive shift
shaft circlip and washer

Inadequate or insufficient lubricant

Worn synchronizer ring

Worn chamfered tooth on sleeve or gear

Distorted shift shaftReplace
Replace
Replenish
Replace
Replace sleeve and gear
Replace
Noise
Inadequate or insufficient lubricant

Damaged or worn bearing(s)

Damaged or worn gear(s)

Damaged or worn synchronizer ring

Damaged or worn chamfered tooth on
sleeve or gearReplenish
Replace
Replace
Replace
Replace

YH4
GRAND
VITARA
7E
DIFFERENTIAL (FRONT) 7E-1
The differential assembly using a hypoid bevel pinion
and gear is installed to the front axle.
4WD control system controls drive force to be trans-
mitted to front axles or not. The reduction ratio varies
depending on transmission or engine type.The differential assembly is decisive in that the drive
power is concentrated there. Therefore, use of genu-
ine parts and specified torque is compulsory. Further,
because of sliding tooth meshing with high pressure
between bevel pinion and gear, it is mandatory to lu-
bricate them by hypoid gear oil.
SECTION 7E
DIFFERENTIAL (FRONT)
CONTENTS
GENERAL DESCRIPTION7E- 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4WD CONTROL SYSTEM7E- 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIAGNOSIS7E- 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIAGNOSIS TABLE7E- 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Differential Assembly7E- 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4WD Control System Diagnostic Flow Table 7E- 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4WD CONTROL CIRCUIT INSPECTION 7E- 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ON-VEHICLE SERVICE7E- 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE SERVICE7E- 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gear Oil Change7E- 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INSPECTION7E-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4WD Control System7E-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Actuator7E-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Pump Assembly7E-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REMOVAL AND INSTALLATION 7E-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Differential Mountings7E-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DISMOUNTING7E-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REMOUNTING7E-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UNIT REPAIR7E-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TIGHTENING TORQUE SPECIFICATIONS7E-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REQUIRED SERVICE MATERIAL7E-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIAL TOOLS7E-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION

YH4
GRAND
VITARA
1. 4WD switch
2. Transfer
3. Blank
4. Blank
5. ECM or PCM
6. Glove box7. Air pump assembly
8. Actuator
9. Axle lock clutch
10. Free axle hub
11. 4WD indicator lamp
7E-2 DIFFERENTIAL (FRONT)
4WD CONTROL SYSTEM
When the 4WD switch is turned ON by shifting the transfer shift lever, ECM (PCM) (G16 and J20 engine models)
or 4WD controller (H25 engine model) actuates (energizes) the air pump assembly. Then positive pressure is sent
from the air pump assembly to the actuator installed to the differential case and causes the axle lock clutch and
the free axle hub in the differential case to be engaged, resulting in the 4WD mode. Only when running in the 4WD
mode, front axles are joined to differential case, and they become free when 2WD mode is used (or when transfer
shift lever is shifted to N position), thereby reducing the power loss.

YH4
GRAND
VITARA
1. 4WD switch
2. Air pump assembly
3. Pump motor
4. Release valve
5. Pressure switch6. Transfer
7. Front differential
8. Air hose and pipe
9. 4WD indicator lamp
10. To ignition switch
11. ECM or PCM
Operation
(refer to ªComponents and Functionsº)
Power supply
(from ECM or PCM)
DIFFERENTIAL (FRONT) 7E-3
System Circuit and Operation

YH4
GRAND
VITARA
7E-4 DIFFERENTIAL (FRONT)
Components and Functions
ComponentFunction
4WD switch
When the transfer shift lever is shifted to 4L or 4H position, this switch turns ON
and causes the 4WD control system to turn ON, unless it is shifted to N or 2H
within 1 second.
ECM or PCM
When the 4WD switch turns ON [unless it turns OFF within 1 second], this com-
ponent actuates the pump assembly. If the pressure in the air pump assembly
fails to increase higher than the set level even after the pump motor has run more
than 10 seconds, this component stops the motor to protect it.
Air pump assembly

Pump motor

Release valve

Pressure switchThe air pump assembly consists of a pump motor, release valve and a pressure
switch.
Pump motor:
Produces positive pressure which actuates the actuator.
Release valve:
Closes when transfer shift lever is shifted to 4H or 4L so that the positive pressure
is applied to the actuator, and opens when N or 2H to release the pressure to the
atmosphere.
Pressure switch:
Turns ON and OFF depending on the pressure level in the pump assembly
(whether higher or lower than the set pressure level). ECM or PCM detects the
pressure level through this switch.
Differential case assembly

Free axle hub

Axle lock clutch

ActuatorThe free axle hub, axle lock clutch and actuator are installed in the differential
left case. The positive pressure produced in the air pump assembly is applied
to the actuator which then pushes the axle lock clutch to be engaged with the free
axle hub. In this state, the drive force is transmitted to the front axle, resulting in
the 4WD mode.
When the actuator is free from the positive pressure [when it is under the atmo-
spheric pressure], the axle lock clutch is pushed back by the return spring force
and cannot be engaged with the free axle hub, resulting in the 2WD mode.
ª4WDº indicator lampIt lights up when 4WD control system is in the 4WD mode.

YH4
GRAND
VITARA
DIFFERENTIAL (FRONT) 7E-5
DIAGNOSIS
DIAGNOSIS TABLE
Differential Assembly
ConditionPossible CauseCorrection
Gear noise
Deteriorated or water mixed lubricant

Inadequate or insufficient lubricant

Maladjusted backlash between bevel
pinion and gear

Improper tooth contact in the mesh between
bevel pinion and gear

Loose bevel gear securing bolts

Damaged side gear(s) or side pinion(s)Repair and replenish
Repair and replenish
Adjust
Adjust or replace
Replace or retighten
Replace
Bearing noise
(Constant noise) Deteriorated or water
mixed lubricant

(Constant noise) Inadequate or insufficient
lubricant

(Noise while coasting) Damaged bearing(s)
of bevel pinion

(Noise while turning) Damaged diff. side
bearing(s) or axle bearing(s)Repair and replenish
Repair and replenish
Replace
Replace
Oil leakage
Worn or damaged oil seal

Excessive oil

Loose differential carrier boltsReplace
Adjust oil level
Replace or retighten
2WD / 4WD
switching error
Defective actuator

Abnormality in 4WD control systemReplace
Inspect referring to ª4WD
CONTROL SYSTEM DIAG-
NOSTIC FLOW TABLEº.
4WD Control System Diagnostic Flow Table
Before performing the trouble diagnosis, check that the transfer and front differential are in good condition and
there is no air leakage from air hoses and the actuator. Refer to ªON-VEHICLE SERVICEº in this section for air
leakage.
[NOTES ON SYSTEM CIRCUIT INSPECTION]

Be sure to read ªPrecautions for Electrical Circuit Serviceº in Section 0A before circuit inspection and observe
what is written there.

For system circuit, refer to the figure of ªGENERAL DESCRIPTIONº in this section.

For terminal arrangement, refer to ª4WD Control Circuit Inspectionº in this section.

YH4
GRAND
VITARA
7E-6 DIFFERENTIAL (FRONT)
STEPACTIONYESNO
1Turn ON ignition switch (but engine at stop) and
check malfunction indicator lamp.
Does lamp light up?Go to step 2.A trouble has
occurred at some
place. Repair it
referring to
MALFUNCTION
INDICATOR LAMP
(ªCHECK ENGINEº
LAMP) CHECK in
DIAGNOSIS of
SECTION 6.
2Check 4WD switch circuit.
Turn ignition switch ON and check that voltage
between terminal C51-2-18 and terminal C51-3-17
(ground) for G16 / J20 (terminal C51-1-11 and terminal
C51-3-26 (ground) for H25) is as follows.

When transfer shift lever is in N or 2H: 10 ± 14 V

When transfer shift lever is in 4L or 4H: 0 ± 1 V
Is the check result satisfactory?Go to step 3.Check 4WD switch
(refer to SECTION
7A), ªB / Orº and ªBº
circuits of 4WD
switch.
If OK, substitute a
known-good ECM
(PCM) and recheck.
3Check power supply.
1) Turn ignition switch ON.
2) Check voltage between C51-2-7 and C51-3-17
(ground) for G16 / J20 (C51-1-15 and C51-3-26
(ground) for H25). The check results should be as
follows.

When transfer shift lever is in N or 2H: 0 ± 1 V

When transfer shift lever is in 4L or 4H: 10 ± 14 V
Is the check result satisfactory?Go to step 4.Check ªRº circuit. If
it is OK, substitute a
known-good ECM
(PCM) and recheck.
4Check air pump assembly circuit.
1) Check for proper connection to air pump
assembly at all terminals.
2) Turn ignition switch ON.
3) Check voltage between C51-2-27 and C51-3-17
(ground) for G16 / J20 (C51-1-18 and C51-3-26
(ground) for H25). The check result should be as
follows.

When transfer shift lever is in 2H or N: 0 ± 1 V

When transfer shift lever is in 4L or 4H
(more than 4 seconds after shifted to 4L or 4H):
10 ± 14 V
Is the check result satisfactory?Go to step 5.Check air pump
assembly referring
to ªON-VEHICLE
SERVICEº, and then
ªPº circuit.
If OK, substitute a
known-good ECM
(PCM) and recheck.
5Check 4WD indicator lamp circuit.
1) Turn ignition switch ON.
2) Check voltage between E61-19 and C51-3-17
(ground) for G16 / J20 (C51-1-7 and C51-3-26
(ground) for H25). The check result should be as
follows.

When transfer shift lever is in 2H or N: 10 ± 14 V

When transfer shift lever is in 4L or 4H: 0 ± 1 V
Is the check result satisfactory?4WD control system
is in good condition.Check ªOr / Bº circuit
(including indicator
lamp and
combination meter).
If OK, substitute a
known-good ECM
(PCM) and recheck.