2002 ISUZU AXIOM low oil pressure

6E±583
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
between the seats. In extreme cases, exhaust blow-by
and damage beyond simple gap wear may occur.
Cracked or broken insulators may be the result of
improper installation, damage during spark plug
re-gapping, or heat shock to the insulator material. Upper
insulators can be broken when a poorly fitting tool is used
during installation or removal, when the spark plug is hit
from the outside, or is dropped on a hard surface. Cracks
in the upper insulator may be inside the shell and not
visible. Also, the breakage may not cause problems until
oil or moisture penetrates the crack later.
TS23994
A/C Clutch Diagnosis
A/C Clutch Circuit Operation
A 12-volt signal is supplied to the A/C request input of the
PCM when the A/C is selected through the A/C control
switch.
The A/C compressor clutch relay is controlled through the
PCM. This allows the PCM to modify the idle air control
position prior to the A/C clutch engagement for better idle
quality. If the engine operating conditions are within their
specified calibrated acceptable ranges, the PCM will
enable the A/C compressor relay. This is done by
providing a ground path for the A/C relay coil within the
PCM. When the A/C compressor relay is enabled,
battery voltage is supplied to the compressor clutch coil.
The PCM will enable the A/C compressor clutch
whenever the engine is running and the A/C has been
requested. The PCM will not enable the A/C compressor
clutch if any of the following conditions are met:

The throttle is greater than 90%.

The engine speed is greater than 6315 RPM.

The ECT is greater than 119
C (246
F).

The IAT is less than 5
C (41
F).

The throttle is more than 80% open.
A/C Clutch Circuit Purpose
The A/C compressor operation is controlled by the
powertrain control module (PCM) for the following
reasons:

It improvises idle quality during compressor clutch
engagement.

It improvises wide open throttle (WOT) performance.

It provides A/C compressor protection from operation
with incorrect refrigerant pressures.
The A/C electrical system consists of the following
components:

The A/C control head.

The A/C refrigerant pressure switches.

The A/C compressor clutch.

The A/C compressor clutch relay.

The PCM.
A/C Request Signal
This signal tells the PCM when the A/C mode is selected
at the A/C control head. The PCM uses this to adjust the
idle speed before turning on the A/C clutch. The A/C
compressor will be inoperative if this signal is not
available to the PCM.
Refer to
A/C Clutch Circuit Diagnosis section for A/C
wiring diagrams and diagnosis for A/C electrical system.
General Description (Evaporative
(EVAP) Emission System)
EVAP Emission Control System Purpose
The basic evaporative emission (EVAP) control system
used on all vehicles is the charcoal canister storage
method. Gasoline vapors from the fuel tank flow into the
canister through the inlet labeled ªTANK.º These vapors
are absorbed into the activated carbon (charcoal) storage
device (canister) in order to hold the vapors when the
vehicle is not operating. The canister is purged by PCM
control when the engine coolant temperature is over 60
C
(140
F), the IAT reading is over 10
C (50
F), and the
engine has been running. Air is drawn into the canister
through the air inlet grid. The air mixes with the vapor and
the mixture is drawn into the intake manifold.
EVAP Emission Control System Operation
The EVAP canister purge is controlled by a solenoid valve
that allows the manifold vacuum to purge the canister.
The powertrain control module (PCM) supplies a ground
to energize the solenoid valve (purge on). The EVAP
purge solenoid control is pulse-width modulated (PWM)
(turned on and off several times a second). The duty
cycle (pulse width) is determined by engine operating
conditions including load, throttle positron, coolant
temperature and ambient temperature. The duty cycle is
calculated by the PCM. The output is commanded when
the appropriate conditions have been met. These
conditions are:

The engine is fully warmed up.

The engine has been running for a specified time.

The IAT reading is above 10
C (50
F).

7A±5 AUTOMATIC TRANSMISSION (4L30±E)
Normal Operation Of 2002 4L30±E
Transmission
Torque Converter Clutch (Electronically
Controlled Capacity Clutch : ECCC)
Application Conditions:
The clutch apply is controlled by moving the converter
clutch control valve by commanding Torque Converter
Clutch (TCC) solenoid using the PWM signal.
The TCC is normally applied in 2nd, 3rd and 4th gears
only when all of the following conditions exist:
Ð The engine coolant temperature is above 70
C
(158
F) and ATF temperature is above 18
C
(64.5
F).
Ð The shift pattern requests TCC apply.
Moreover, TCC is always applied in 2nd, 3rd and 4th
gears when the transmission oil temperature is above
135
C (275
F).
This mode should be canceled at 125
C (257
F).
ATF Warning Lamp
The ATF warning lamp will be constantly on (not flashing)
if the transmission oil temperature is above 145
C
(293
F).
The ATF warning lamp goes off again when the
transmission oil temperature is below 125
C (257
F).
Reverse Lock Out
With the selector lever in reverse position, the PCM will
not close the PWM solenoid until the vehicle is below 11
km/h (6.8 mph), thus preventing reverse engagement
above this speed.
Diagnosis
Introduction
The systematic troubleshooting information covered by
this Section offers a practical and systematic approach to
diagnosing 4L30±E transmission, using information that
can be obtained from road tests, electrical diagnosis, oil
pressure checks or noise evaluation.
The key to correcting a complaint is to make use of all of
the available symptoms and logically letting them direct
you to the cause.
When dealing with automatic transmission complaints, it
is best to gather as many symptoms as possible before
making the decision to remove the transmission from the
vehicle.
Frequently, the correction of the complaint does not
require removal of the transmission from the vehicle.
Driver Information
To analyze the problem fill out a complete description of
the owner's complaint.
Please draw a circle around the right information and
complete the following form. (The next page is an
example of a completed form). You can draw a circle
around many numbers if you are not sure.

7A±18
AUTOMATIC TRANSMISSION (4L30±E)
Chart 9c: Coastdown Harsh Shift Or Clunk At 3±2 Downshift
StepActionYe sNo
1Check line pressure. Refer to Line Pressure Test in this section.
Was line pressure normal?
Go to Step 2
Use Chart 15b:
Possible Causes
of High Line
Pressure in this
section
2Does DTC P1850 set?
Diagnose P1850
first
Replace band
apply solenoid
(PWM) (323)
Chart 10: Intermittent 4TH TO 2ND Gear Downshift At Steady Speed
StepActionYe sNo
1Check for consistent speed sensor reading with scan tool.
Was the reading correct?Replace mode
switch for
intermittent
contact.
Go to Step 2
21. Check for wiring harness damage or short to ground. If OK, go
to
(2).
2. Check transmission speed sensor connections. If OK, go to
(3).
3. Replace transmission speed sensor.
Was the replacement complete?
Ð
Replace speed
sensor.
Chart 11: Engine Flare At Shifting During Turning Only (Usually With Warm Engine)
StepActionYe sNo
1Check for oil leaks at transmission.
Was the problem found?Replace
transmission oil
filter and gasket
Ð
Chart 12: Engine Flare During 1±2 Or 2±3 Shift
StepActionYe sNo
1Check line pressure. Refer to Line Pressure Test in this section.
Was line pressure normal?
Go to Step 2
Use Chart 15a:
Possible Causes
of Low Line
Pressure in this
section
21. Check for a stuck 1±2 accumulator valve (320).
2. Check for servo piston (106) leaks.
3. Check for a stuck band apply solenoid (323).
Was line pressure normal?
Repair or replaceÐ

7A±20
AUTOMATIC TRANSMISSION (4L30±E)
Chart 15a: Possible Causes of Low Line Pressure
StepActionYe sNo
1Check oil level.
Was the problem found?
Fill with ATFGo to Step 2
2Check for defective throttle position sensor.
Was the problem found?Replace throttle
position sensor
Go to Step 3
3Check for plugged, loose, or damaged oil filter (79).
Was the problem found?Inspect oil filter,
tighten bolts or
replace oil filter
(79)
Go to Step 4
4Check for a stuck force motor plunger (404). (Adapter case valve
body)
Was the problem found?Replace force
motor plunger
(404)
Go to Step 5
5Check for a stuck feed limit valve (412). (Adapter case valve body)
Was the problem found?Replace feed limit
valve (412)
Go to Step 6
6Check for loose converter bolts (4 & 5).
Was the problem found?Tighten converter
bolts (4 & 5)
Go to Step 7
7Check for a stuck pressure regulator valve (217). (Oil pump)
Was the problem found?Replace pressure
regulator valve
(217)
Go to Step 8
8Check for a stuck boost valve (213).(Oil pump)
Was the problem found?Replace boost
valve (213)
Go to Step 9
9Check for blocked intermediate oil passages to pressure
regulator valve. (Oil pump)
Was the problem found?
Replace oil pumpGo to Step 10
10Check for defective oil pump (9, 201, 202 & 228).
Was the problem found?
Replace oil pumpGo to Step 11
11Check for internal leaks.
± Check balls missing or out of location in valve bodies
± Seals cut or damaged
± Gaskets defective, etc.
Was the problem found?Install balls, or
correct ball
location
Replace seals
Replace gaskets
Ð

7A±22
AUTOMATIC TRANSMISSION (4L30±E)
Chart 16: Possible Causes Of
Transmission Fluid Leaks
Before attempting to correct an oil leak, the actual source
of the leak must be determined. In many cases, the
source of the leak may be difficult to determine due to
ªwind flowº around the engine and transmission.
The suspected area should be wiped clean before in-
specting for the source of the leak.Oil leaks around the engine and transmission are gener-
ally carried toward the rear of the vehicle by the air
stream. In determining the source of an oil leak, the fol-
lowing two checks should be made:
1. With the engine running, check for external line
pressure leaks.
2. With the engine off, check for oil leaks due to the
raised oil level caused by drainback of converter oil
into the transmission.
Possible Causes Of Fluid Leaks Due To Sealing Malfunction
240RX008
Legend
(1) Electrical Connector (Main Case) Seal
(2) Transmission Vent (Breather)
(3) Speed Sensor O±Ring
(4) Extension (Adapter) Lip Seal
(5) Extension (Adapter) to Main Case Gasket
(6) Overfill and Oil Drain Screws Gasket
(7) Oil Pan Gasket (Main Case)
(8) Selector Shaft Seal(9) Oil Cooler Connectors (2)
(10) Oil Pan Gasket (Adapter Case)
(11) Converter housing attaching bolts not correctly
torqued
(12) Converter Housing Lip Seal
(13) Line Pressure Tap Plug
(14) Electrical Connector (Adapter Case) Seal
(15) Adapter Case Seal Rings (2)

7A±23 AUTOMATIC TRANSMISSION (4L30±E)
Stall Test
The stall test allows you to check the transmission for
internal abrasion and the one way clutch for slippage.
Torque converter performance can also be evaluated.
The stall test results together with the road test results will
identify transmission components requiring servicing or
adjustment.
Stall Test Procedure:
1. Check the level of the engine coolant, the engine oil,
and the automatic transmission fluid. Replenish if
necessary.
2. Block the wheels and set the parking brake.
3. Connect a tachometer to the engine.
4. Start the engine and allow it to idle until the engine
coolant temperature reaches 70 ± 80
C (158 ±
176
F).
5. Hold the brake pedal down as far as it will go.
6. Place the selector in the ªDº range.
7. Gradually push the accelerator pedal to the floor.
The throttle valve will be fully open.
Note the engine speed at which the tachometer
needle stabilizes.
Stall Speed : 2,100 +150 rpm
NOTE: Do not continuously run this test longer than 5
seconds.
8. Release the accelerator pedal.
9. Place the selector in the ªNº range.
10. Run the engine at 1,200 rpm for one minute.
This will cool the transmission fluid.
11. Repeat Steps 7 ± 10 for the ª3º, ª2º, ªLº and ªRº
ranges.
Line Pressure Test
The line pressure test checks oil pump and control valve
pressure regulator valve function. It will also detect oil
leakage.
Line Pressure Test Procedure:
1. Check the level of the engine coolant, the engine oil,
and the automatic transmission fluid.
Replenish if required.
2. Block the wheels and set the parking brake.
3. Remove the pressure detection plug at the left side of
the transmission case.
Set J±29770±A pressure gauge and adapter to the
pressure detection plug hole.
241RS001
4. Start the engine and allow it to idle until the engine
coolant temperature reaches 70 ± 80
C (158 ±
176
F).
5. Hold the brake pedal down as far as it will go.
6. Place the selector in the ªDº range.
7. Note the pressure gauge reading with the engine
idling.
8. Gradually push the accelerator pedal to the floor. The
throttle valve will be fully open.
Note the pressure gauge reading with the accelerator
pedal fully depressed.
NOTE: Do not continuously run this test longer than 5
seconds.
9. Release the accelerator pedal.
10. Place the selector in the ªNº range.
11. Run the engine at 1,200 rpm for one minute.
This will cool the transmission fluid.
12. Repeat Steps 7 ± 11 for the ª3º, ª2º, ªLº, and ªRº
ranges.
13. Install a pressure detection plug to the transmission
case, applying recommended thread locking agent
(LOCTITE 242) or its equivalent to thread of plug.
Make sure that thread is cleaned before applying
locking agents.
14. Tighten the pressure detection plug to the specified
torque.
Torque: 9 ± 14N´m (7 ± 10lb ft)

7A±72
AUTOMATIC TRANSMISSION (4L30±E)
10. Remove retainer (13), 2±3 shift valve (14), and spring
(15).
11. Remove spring pin (16), plug (17), spring (18), and
low pressure control valve (19).
12. Remove spring pin (20), plug (21), and band control
screen assembly (22).
13. Remove spring pin (23), plug (24), 1±2 accumulator
valve (25), and 1±2 accumulator control valve (26).
14. Remove check ball (27) from valve body (28).
Inspection And Repair
Inspect for the following, and replace any damaged or
worn parts:
1. Damage or wear to each valve.
2. Damage in oil passeges.
3. Cracks or damage to valve body.
4. Valve operations.
5. Spring fatigue.
Reassembly
1. Install 1±2 accumulator control valve (26), 1±2
accumulator valve (25), plug (24), and spring pin (23).
2. Install band control screen assembly (22), plug (21),
and spring pin (20).
3. Install low pressure control valve (19), spring (18),
plug (17), and spring pin (16).
4. Install spring (15), 2±3 shift valve (14), retainer (13),
solenoid B (12), and spring pin (11).
5. Install spring (10), 1±2/3±4 shift valve (9), retainer (8),
solenoid A (7), and spring pin (6).
6. Install waved washer (5), band control solenoid (3),
and pin (4).
7. Install manual valve (2).
8. Install check ball (27) to valve body (28).9. Install gasket (valve body/transfer plate) and transfer
plate using two J±3387±2 guide pins.

Install two 11mm bolts.
Torque: 13 Nwm (113 lb in)244RS004

Install gasket (transfer plate/main case).

7A1±6
TRANSMISSION CONTROL SYSTEM (4L30±E)
Shift Control
The transmission gear is shifted according to the shift
pattern selected by the driver. In shifting gears, the gear
ratio is controlled by the ON/ OFF signal using the shift
solenoid A and the shift solenoid B.
Band Apply Control
The band apply is controlled when in the 3±2 downshift
(engine overrun prevention) and the garage shift (shock
control).
The band apply solenoid is controlled by the signal from
the Pulse Width Modulation (PWM) to regulate the flow of
the oil.
Torque Converter Clutch Control
(Electronically Controlled Capacity Clutch
= ECCC)
The clutch apply is controlled by moving the converter
clutch valve by commanding Torque Converter Clutch
(TCC) solenoid using the PWM signal.
Line Pressure Control
The throttle signal allows the current signal to be sent to
the force motor. After receiving the current signal, the
force motor activates the pressure regulator valve to
regulate the line pressure.
On±Board Diagnostic System
Several malfunction displays can be stored in the
Powertrain Control Module (PCM) memory, and read out
of it afterward.
The serial data lines, which are required for the testing of
the final assembly and the coupling to other electronic
modules, can be regulated by this function.
Fail Safe Mechanism
If there is a problem in the transmission system, the PCM
will go into a ªbackupº mode.
The vehicle can still be driven, but the driver must use the
select lever to shift gears.
Torque Management Control
The transmission control side sends the absolute spark
advance signal to the engine control side while the
transmission is being shifted. This controls the engine
spark timing in compliance with the vehicle running
condition to reduce the shocks caused by the change of
speed.
ATF Warning Control
The oil temperature sensor detects the ATF oil
temperature to control the oil temperature warning, TCC,
and the winter mode.
Reverse Lock Out Control
With the selector lever in reverse position, the PCM will
not close the PWM solenoid until the vehicle is below 11
km/h (6.8 mph), thus preventing reverse engagement
above this speed.
Downhill Control
This mode is automatically activated from ªNORMALº
mode only when downhill conditions are recognized.
The shift pattern is identical to ªNORMALº mode except
3-4 and 4-3 shift lines at low throttle modified to get engine
braking on a larger speed range.
ECCC lines unchanged compared to ªNORMALº mode.
Uphill Control
When Uphill condition are recognized the 2-3 and 3-4 shift
and TCC apply take place only when the engine torque is
sufficient in order to avoid shift hunting.