Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 635

7A1–40 AUTOMATIC TRANSMISSION (4L30-E)

CHART 15b: POSSIBLE CAUSES OF HIGH LINE PRESSURE

PERFORM PRELIMINARY INSPECTION FIRST!

ON-VEHICLE SERVICE

TRANSMISSION REMOVED

Small
valve
body

Oil
pump

































OK

OK

OK

(  ) Refer to Parts List at the end of this Section.

NOTE: If transmission is operating in back-up mode, high line pressure will be

present.

Check for defective throttle position sensor

OK

Check for loose bolts (4 & 5)

OK

OK

Check for pressure regulator valve (208) stuck

Check for boost valve (205) stuck

Check for force motor plunger (404) stuck

(Remove force motor. Shake and listen for rattle.)

(Open circuit/Intermittent)

Check for feed limit valve (412) stuck

Check for internal leaks
– Check balls missing or out of location in valve bodies
– Seals cut or missing
– Gaskets defective, etc.

AUTOMATIC TRANSMISSION (4L30-E) 7A1–41

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 “wind flow” around the engine and
transmission.

The suspected area should be wiped clean of all oil before inspecting for the source of the leak.

Oil leaks around the engine and transmission are generally carried toward the rear of the car by the air
stream. In determining the source of an leak, the following 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.

7A1–42 AUTOMATIC TRANSMISSION (4L30-E)

POSSIBLE CAUSES OF FLUID LEAKS 

DUE TO SEALING MALFUNCTION

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) Oil drain plug 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)

6

7

5

9

10

8

11

12

2

3

4

1

14

13

15

240LW004

AUTOMATIC TRANSMISSION (4L30-E) 7A1–43

STALL TEST

The stall test allows you to check the transmission for
internal abrasion and the oneway 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 “D” 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

Standard

2200 ± 150 rpm

NOTE:

Do not continuously run this test longer than 5
seconds.

8. Release the accelerator pedal.
9. Place the selector in the “N” 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 “3”, “2”, “L” and “R”

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 pressure gauge, adapter to the pressure detection
plug hole.
Gauge and adapter: 5-8840-0004-0 (J-21867)