2004 ISUZU TF SERIES check engine

7A2-74 TRANSMISSION CONTROL SYSTEM (AW30–40LE) (V6 3.5L)

DTC U2104 (FLASHING CODE 65) CAN BUSS OFF

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Circuit Description
The automatic transmission control system in AW30-
40LE uses high speed CAN bus system. The individual
CAN bus systems are connected via two interfaces and
can exchange information and data. This allows control
modules that are connected to different CAN bus
systems to communicate. Transmission control
modules in the vehicle that require continuous, rapid
communication are connected to the high speed CAN
bus. The automatic transmission is continuously notified
of the current engine load status. Since the automatic
transmission control module has to react immediately to
load status changes, rapid communication is required
between the engine control module and the automatic
transmission control module. The high speed CAN bus
in the AW30-40LE is designed as a two-wire CAN bus
(twisted pair). The wires are shielded and twisted. The
transmission rate is 500K band.

Condition for setting the DTC
The TCM detects CAN BUS OFF for 0.18 sec (After the
TCM leaves a communucation start with the ECM fo
r
0.64 sec) continously..
Action Taken When The DTC Sets

The throttle pressure is max.

The TCM judges APS(Accelerator Position Sensor)
angle is 0% at the time of shift operation.
 No throttle pressure reduction.

No torque reduction.

No lock-up control.
 No slope control.

No squat control.

Check Trans ON.

DTC stored.

Engine REV is 7000 rpm.
 Coolant tempreature is 80

C.

7A3-12 ON-VEHICLE SERVICE (AW30 –40LE)

Manual Shifting Test
NOTE: With this test, it can be determined whether the
trouble lies within the electrical circuit or is a mechanical
problem in the transmission.
1. Disconnect TCM connector
Inspect manual driving operation
2. Inspect manual driving operation
Check that the shift and gear positions correspond
with the table.
If the “L", “2", “3" and “D" range gear positions are
difficult to distinguish, do perform the following road
test.
While driving, shift through the “L", “2", “3" and “D"
ranges. Check that the gear change corresponds to
the gear position.
If any abnormality is found in the above test, do
perform the stall, time lag or gear change tests.



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3. Connect TCM connector
With the engine off, connect the TCM connector.


Stall Test



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The object of this test is to check the overall
performance of the transmission and engine b
y
measuring the maximum engine speeds at the “D" and
“ R" ranges.
NOTE:
1. Perform the test at normal operation fluid
temperature (50 – 80 
C or 122 – 176 
F).
2. Do not continuously run this test longer than 5 seconds.

ON-VEHICLE SERVICE (AW30 –40LE) 7A3-13

Measure Stall Speed
1. Chock the four wheels.
2. Mount an engine tachometer.
3. Fully apply the parking brake.
4. Step down strongly on the brake pedal with your left foot.
5. Start the engine.
6. Turn off the A/C.
7. Shift into the “D" range. Step all the way down on
the accelerator pedal with your right foot. Quickl
y
read the highest engine rpm.
Stall speed: 2100






150 rpm
8. Perform the same test in the “R" range.
Evaluation

1. If the engine speed is the same for both ranges but
lower than the specified value:
 Engine output is insufficient.
 Stator one-way clutch is not operating properly.
NOTE: If more than 600 rpm below the specified value,
the torque converter could be faulty.
2. If the stall speed in “D" range is higher than
specified:
 Line pressure too low
 Forward clutch slipping
 No.2 one-way clutch not operating properly
3. If the stall speed in “R" range is higher than
specified:
 Line pressure too low
 Direct clutch slipping
 No.3 brake slipping
4. If the stall speed in the “R" and “D" ranges are
higher than specified:
 Line pressure too low
 Improper fluid level

Time Lag Test



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If the shift lever is shifted while the engine is idling,
there will be a certain time elapse or lag before the
shock can be felt. This is used for checking the
condition of the forward clutch, direct clutch, No.3
brake, and No.2 one-way clutch.
NOTE:
1. Perform the test at normal operation fluid
temperature (50 – 80 C or 122 – 176 F)
2. Be sure to allow one minute interval between tests.
3. Make three measurements and take the average value.

7A3-14 ON-VEHICLE SERVICE (AW30 –40LE)

Measure Time Lag
1. Fully apply the parking brake.
2. Start the engine. Check idling speed (A/C OFF).
3. Shift the shift lever from “N" to “D" range. Using a
stopwatch, measure the time it takes from shifting
the lever until the shock is felt.
Time lag: Less than 0.7 seconds
4. In same manner, measure the time lag for “N"


“R".
Time lag: Less than 1.2 seconds
Evaluation
1. If “N" 
“ D" time lag is longer than specified:

Line pressure too low
 Forward clutch malfunction
 No.2 one-way clutch not operating properly
2. If “N" 
“ R" time lag is longer than specified:

Line pressure too low
 Direct clutch malfunction
 No.3 brake malfunction
3. If both time lag is longer than specified:

Line pressure too low

Hydraulic Test



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Preparation

1. Warm up the transmission fluid.
2. Remove the transmission case test plug and mount the hydraulic pressure gauge.
Oil pressure gauge: J –29770 –A
NOTE: Perform the test at normal operation fluid
temperature (50 – 80 
C or 122 – 176 
F).

ON-VEHICLE SERVICE (AW30 –40LE) 7A3-15

Measure Line Pressure
1. Fully apply the parking brake and chock the four
wheels.
2. Start the engine and check idling rpm.
3. Shift into “D" range, step down strongly on the brake
pedal with your left foot and, while manipulating the
accelerator pedal with the right foot, measure the
line pressures at the engine speeds specified in the
table.
4. In the same manner, perform the test in “R" range.


Line pressure kPa (kg/cm2/psi) Engine
speed “D" range “R" range
Idling 323 – 382
(3.3 – 3.9/47 – 55) 500 – 598
(5.1 – 6.1/73 – 87)
Stall 1,137 – 1,274 (11.6–13.0/165–185) 1,499 – 1,833
(15.3–18.7/218–266)
Evaluation
1. If the measured values at all ranges are higher than
specified:

Pressure control solenoid defective
 Primary regulator valve defective
2. If the measured values at all ranges are lower than
specified:

Primary regulator valve defective
 Oil pump defective
 Pressure control solenoid defective
3. If pressure is low in “D" range only:

“ D" range circuit fluid leakage
4. If pressure is low in “R" range only:

“ R" range circuit fluid leakage
Road Test
NOTE: Perform the test at normal operation fluid
temperature (50 – 80 
C or 122 – 176 
F).
“D" Range Test in “NORMAL", and
“POWER" Pattern Ranges
Shift into the “D" range and hold the accelerator pedal
constant at the 50% and 100% throttle valve opening
positions.
Push in one of the pattern selector buttons and check
the following:

1. 1 –2, 2 –3, 3 –OD and lock-up, up-shifts should take
place, and shift points should conform to those
shown in the automatic shift diagram.


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7A3-16 ON-VEHICLE SERVICE (AW30 –40LE)

Evaluation
i. If there is no 1 
2 upshift:

Solenoid S2 is stuck
 1 –2 shift valve is stuck
ii. If there is no 2 
3 upshift:

Solenoid S1 is stuck
 2 –3 shift valve is stuck
iii. If there is no 3 
OD upshift (throttle valve opening
1/2):

Solenoid S2 is stuck
 3 –OD shift valve is stuck
iv. If the shift point is defective: Refer to TROUBLESHOOTING CHART in this
section.
v. If the lock-up is defective: Refer to TROUBLESHOOTING CHART in this
section.
2. In the same manner, check the shock and slip at the 1 
2, 2 
3 and 3 
OD upshifts.
NOTE: Drive the vehicle on level ground.
Evaluation
If the shock is excessive:
Refer to TROUBLESHOOTING CHART in this section.
3. Run at “D" range lock-up or OD gear and check fo
r
abnormal noise and vibration.
NOTE: The check for the cause of abnormal noise and
vibration must be made with extreme care as it could
also be due to loss of balance in the propeller shaft,
differential, the torque converter, etc. or insufficient
bending, rigidity, etc. in the power train.



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4. While running in “D" range, 2nd, 3rd gears and OD,
check to see that the possible kick-down vehicle
speed limits for 2 1, 3 1, 3 2, OD 3 and
OD 
2 kick-downs conform to those indicated on
the automatic shift diagram.



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5. Check for abnormal shock and slip at kick-down.
6. While running in “D" range, OD gear or “lock-up",
shift to “2" and “L" ranges and check the engine
braking effect at each of these ranges.
7. Also check to see that downshift is made from 3 
2
or from OD to 3 and then to 2 immediately and that
2 
1 downshift point is within the limits shown in the
diagram when tested by releasing the accelerato
r
pedal and shifting into position of “L" while driving in
the third gear or in overdrive.

ON-VEHICLE SERVICE (AW30 –40LE) 7A3-17

Evaluation
i. If there is no engine braking effect in the “2" range:

Second coast (No.1) brake is defective.

ii. If there is no engine braking effect in the “L" range:

First and reverse (No.3) brake is defective.






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iii. Also check to see that downshift is made from 3 2
or from OD to 3 and then to 2 immediately and that
2 
1 downshift point is within the limits shown in the
diagram when tested by releasing the accelerato
r
pedal and shifting into “L" position while driving in
the third gear or in overdrive.



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“ 2" Range Test
Shift into “2" range and, while driving with the
accelerator pedal held constantly at the specified point
(throttle valve opening 50% and 100%), push in one o
f
the pattern selectors (only for 4
4) and check on the
following points.
1.
At each of the above throttle openings, check to see
that the 1 
2 upshift takes place and that the shift
points conform to those shown on the automatic
shift diagram.
NOTE: There is no OD and no lock-up in the “2" range.


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2. While running in the “2" range and 2nd gear,
release the accelerator pedal and check the
engine's braking effect.
3. Check for 2 
1 downshift and abnormal noise at
acceleration and deceleration, and for shock at
upshift and downshift.






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7A3-18 ON-VEHICLE SERVICE (AW30 –40LE)

“ L" Range Test
1. While running above 80 km/h (50 mph) in the “D"
range, release your foot from the accelerator pedal
and shift into the “L" range.
Then check to see that the 2 
1 downshift occurs at
the specified point shown on the automatic shift
diagram.



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2. While running in the “L" range, check to see that
there is no upshift to 2nd gear.
3. While running in the “L" range, release the
accelerator pedal and check the engine braking
effect.
4. Check for abnormal noise during acceleration and deceleration.







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“ R" Range Test
Shift into the “R" range and, while starting at full throttle,
check for slipping.




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“ P" Range Test
Stop the vehicle on a grade (more than 9%) and afte
r
shifting into the “P" range, release the parking brake.
Then check to see that the parking lock pawl holds the
vehicle in place.