Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 632

7A1–28 AUTOMATIC TRANSMISSION (4L30-E)

Normal line pressure

Check internal linkage:
– Manual linkage (58) not moving 

manual valve (326)

Check for internal mechanical
damage:
– Turbine shaft (506) broken loose
– Overrun roller clutch (516) broken 

loose

– Etc.

Low line pressure

Use CHART 15a: POSSIBLE CAUSES
OF LOW LINE PRESSURE on page 
7A1-39

Check

line pressure

CHART 2: NO FORWARD GEARS IN ANY RANGE/NO REVERSE

PERFORM PRELIMINARY INSPECTION FIRST!

Refer to Line Pressure chart 

( 

in this Section.

)

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

AUTOMATIC TRANSMISSION (4L30-E) 7A1–29

Check

line pressure

CHART 3: NO ENGINE BRAKE IN ANY RANGE

PERFORM PRELIMINARY INSPECTION FIRST!

Refer to Line Pressure chart 

( 

in this Section.

)

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

Low line pressure

Use CHART 15a: POSSIBLE CAUSES
OF LOW LINE PRESSURE on page 
7A1-39

Normal line pressure

Check for overrun clutch leaks caused
by:
– Damaged piston lip (513)
– Check ball defective (504)

Check for overrun lockout valve (705)
stuck by foreign material

Check for leaks at turbine shaft (506)
Caused by:
– Teflon seal rings damaged (508)
– Excessive wear of turbine shaft 

bearing surfaces

7A1–30 AUTOMATIC TRANSMISSION (4L30-E)

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

CHART 4: POOR SHIFTING IN ALL GEARS (ALL HARSH OR ALL SOFT)

PERFORM PRELIMINARY INSPECTION FIRST!

Check

line pressure

Low line pressure

Use CHART 15a: POSSIBLE CAUSES
OF LOW LINE PRESSURE on page 
7A1-39

High line pressure

Use CHART 15b: POSSIBLE CAUSES
OF HIGH LINE PRESSURE on page 
7A1-40

Check for these conditions which
could affect clutch apply time:

•

Defective band apply solenoid
(323)

•

Defective servo or/and
accumulator piston

•

Excessive clutch piston travel

Check of possible causes of internal
leaks:
– Cut or damaged sealing ring(s)
– Damaged sealing gasket (s)
– Check ball missing or out of 

location in 2nd and 3rd clutch 
pistons

Check for causes of burned clutch
plates or band

Refer to Line Pressure chart 

( 

in this Section.

)

AUTOMATIC TRANSMISSION (4L30-E) 7A1–31

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

CHART 5a: DELAYS IN DRIVE AND REVERSE

PERFORM PRELIMINARY INSPECTION FIRST!

CHART 5b: DELAYS IN REVERSE ONLY

PERFORM PRELIMINARY INSPECTION FIRST!

Check

line pressure

Normal line pressure

More than 3 second delay in drive and

reverse with engine off 1 hour or less

Teflon seals (508) on turbine shaft
damaged

Low line pressure

Use CHART 15a: POSSIBLE CAUSES
OF LOW LINE PRESSURE on page 
7A1-39

NOTE: A short delay (less than 3
seconds) when first engaging drive or
reverse after allowing vehicle to sit
overnight is normal.

Refer to Line Pressure chart 

( 

in this Section.

)

Check

line pressure

Refer to Line Pressure chart 

( 

in this Section.

)

Normal line pressure

Main case to valve body gasket (88)
damaged

Reverse check ball (85) in valve body
(84) missing or out of location

Low line pressure

Use CHART 15a: POSSIBLE CAUSES
OF LOW LINE PRESSURE on page
7A1-39

Check for restrictions at valve body
transfer plate orifice