1998 SUZUKI GRAND VITARA Pcm

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.

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
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.

YH4
GRAND
VITARA
DIFFERENTIAL (FRONT) 7E-7
1
1. ECM (PCM); viewed from harness side
4WD CONTROL CIRCUIT INSPECTION
Voltage Check [G16 and J20 engine models]
Check for input or output voltage (voltage between each circuit and
body ground) of ECM (PCM) with ECM (PCM) connector con-
nected and ignition switch turned ON.
TER-
MINALCIRCUITWIRE
COLORNORMAL
VOLTAGECONDITION
E6110 ± 14 VTransfer shift lever: 2H or NE61-
194WD Indicator lampOr / B0 ± 1 V4 seconds after transfer shift lever shifted
to 4H or 4L
C51 2Air pump assembly0 ± 1 VTransfer shift lever: 2H or NC51-2
-7(Pump motor and release
valve)R10 ± 14 V1 seconds after transfer shift lever shifted
to 4H or 4L
C51-24WD switchB/Or10 ± 14 VTransfer shift lever: 2H or N
-184WD switchB/Or0 ± 1 VTransfer shift lever: 4H or 4L
C51-
3-17GroundB/Bl0 ± 1 V±
C51 2Airpumpassembly0 ± 1 VTransfer shift lever: 2H or NC51-2
-27
Air um assembly
(pressure switch)P10 ± 14 V4 seconds after transfer shift lever shifted
to 4H or 4L

YH4
GRAND
VITARA
7E-8 DIFFERENTIAL (FRONT)
1. ECM (PCM); viewed from harness side
Voltage Check [H25 engine model]
TER-
MINALCIRCUITWIRE
COLORNORMAL
VOLTAGECONDITION
C51 110 ± 14 VTransfer shift lever: 2H or NC51-1
-74WD Indicator lampOr / B0 ± 1 V4 seconds after transfer shift lever shifted
to 4H or 4L
C51 1Air pump assembly0 ± 1 VTransfer shift lever: 2H or NC51-1
-15(Pump motor and release
valve)R10 ± 14 V1 seconds after transfer shift lever shifted
to 4H or 4L
C51-14WD switchB/Or10 ± 14 VTransfer shift lever: 2H or N
-114WD switchB/Or0 ± 1 VTransfer shift lever: 4H or 4L
C51-3
-26GroundB/Bl0 ± 1 V±
C51-1Airpumpassembly0 ± 1 VTransfer shift lever: 2H or NC51-1
-18
Air um assembly
(pressure switch)P10 ± 14 V4 seconds after transfer shift lever shifted
to 4H or 4L

YH4
GRAND
VITARA
1. To door switch (driver side) B / Bl
2. To transmission range switch G / Bl
(A / T vehicle only, if equipped) L
3. To transmission range switch G / O
(A / T vehicle only, if equipped) 2
4. To transmission range switch Y / G
(A / T vehicle only, if equipped) D
5. To transmission range switch O / Bl
(A / T vehicle only, if equipped) N
6. To transmission range switch O / G
(A / T vehicle only, if equipped) P
7. To transmission range switch R
(A / T vehicle only, if equipped) R
8. To ground B
9. To PCM (A / T vehicle only) W / B
10. To ECT sensor Y / W
11. To fuel level gauge Bl / W
12. To ground B / Y
13. To combination switch G / Y
NOTE:
Terminal arrangement of coupler viewed from harness side.
Coupler A Coupler B Coupler C
Coupler A Coupler B Coupler C
1. Blank ÐÐ
2. Blank ÐÐ
3. To ignition switch B / W
4. Blank ÐÐ
5. To ABS control module Bl / O
(if equipped)
6. To PCM (A / T vehicle only) Gr / Bl
7. To ABS control module Br
(if equipped)
8. To VSS Bl / Y
9. To combination switch G / R
10. To SDM (if equipped) Y / G or Bl
11. To main fuse W / Bl
12. To fuse box W
13. To combination switch R
14. To ECM (PCM for A / T vehicle) V
(if equipped)
15. To ECM (PCM for A / T vehicle) V / Y
16. To ECM (PCM for A / T vehicle) O / B
(if equipped)1. To ground B
2. To ECM (PCM for A / T vehicle) Br
3. To ignition switch (if equipped) V / R
4. To brake fluid level switch R / B
5. To parking brake switch V
6. To seat belt switch (if equipped) Gr / R
7. To generator W / R
8. To oil pressure switch Y / B
9. To combination switch R / Y
10. To ignition switch (if equipped) Bl / R or CHECK
or ENGINE
or ABSif equipped
if equippedif equipped
INSTRUMENTATION / DRIVER INFORMATION 8C-3