Isuzu N-Series. Manual - part 931

Transmission Control System (Smoother) 7A-179

1. Install the Tech 2.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Observe the following transmission data with

the Tech 2. Reprogram correct vehicle
information if incorrect. Refer to Transmission
Control Module (TCM) Replacement in this
section.

• Engine Type
• Transmission Type
• Speedometer Driven Gear Teeth

5. Observe the following transmission data with

the Tech 2. Relearn if indicates Not Learned.
Refer to Transmission Control Module (TCM)
Replacement in this section.

• Engine Type Learning Status
• Transmission Type Learning Status
• Speedometer Driven Gear Learning Status
• Gear Position Learning Status
• Torque Learning Status

6. Learning procedure must be done whenever

any of the relating parts are replaced, removed
or repaired. Refer to Programming & Learning
Guideline in this section.

Did you complete the action?

—

Go to Step 3

—

Operate the selector lever while observe the
Selector Position parameter with the Tech 2.

Does the Selector Position parameter indicate
correct position?

—

Go to Step 4

Refer to DTC P0906

and P0907

1. Inspect for correct ATF level. Refer to ATF

inspection in this section.

2. Inspect for external leakage.
3. Repair or add ATF as necessary.

Did you complete the action?

—

Go to Step 5

—

1. Lift the driving wheels or drive the vehicle.
2. Start the engine.
3. Monitor the DTC Information with the Tech 2.

Are any DTC(s) set?

—

Go to Applicable

DTC

Go to Step 6

1. Start the engine if stopped.
2. Put the vehicle with the following conditions:

• Selector lever N position
• 1st gear start switch OFF
• Economy mode switch OFF
• Emergency switch OFF
• Emergency shift switch N position
• PTO switch(s) and/or lever OFF

3. Operate the selector lever from N to D while

applying the brake pedal.

Does the gear position display in the instrument
panel cluster (IPC) indicate A?

—

Go to Step 7

Go to Step 20

Step

Action

Value(s)

Yes

7A-180 Transmission Control System (Smoother)

Does the transmission warning lamp OFF in the
IPC?

—

Go to Step 8

If DTC is set, refer to

applicable DTC.

If no DTC, Go to

Transmission

Warning Lamp

Always ON

Does the ECONO indicator lamp OFF in the IPC?

—

Go to Step 9

Go to Chart 2 of 4

Step 13

Does the 1st START indicator lamp OFF in the IPC?

—

Go to Step 10

Go to Chart 2 of 4

Step 28

Let the vehicle run while observing the Current
Gear and Desired Gear Position parameter with the
Tech 2.

Does all forward gear automatically engage or
disengage except 1st gear, and Current Gear
parameter follow the Desired Gear Position
parameter?

—

Go to Step 11

If DTC is set, refer to

applicable DTC.

If no DTC, Go to

Step 19

1. Stop the vehicle.
2. Economy mode switch ON.
3. Let the vehicle run while observing the Current

Gear and Desired Gear Position parameter
with the Tech 2.

Does all forward gear automatically engage or
disengage except 1st gear, and the timing of up-
shifting earlier than normal auto shifting?

—

Go to Step 12

Go to Chart 2 of 4

Step 1

1. Stop the vehicle.
2. Operate the selector lever to + and

−. Slightly

move the vehicle as necessary.

Does the gear position display in the IPC indicate 1,
2 or 3 when the selector lever is operated?

—

Go to Step 13

If DTC is set, refer to

applicable DTC.

If no DTC, Go to

Step 19

1. Stop the vehicle.
2. Operate the selector lever to A.
3. 1st gear start switch ON
4. Let the vehicle run while observing the Current

Gear and Desired Gear Position parameter
with the Tech 2.

Does the 1st gear automatically engage whenever
vehicle starting?

—

Go to Step 14

Go to Chart 2 of 4

Step 18

1. Stop the vehicle.
2. Operate the selector lever to R. Slightly move

the vehicle as necessary.

Does the reverse gear engage?

—

Go to Step 15

If DTC is set, refer to

applicable DTC.

If no DTC, Go to

Step 19

1. Stop the vehicle.
2. Put the vehicle with the following conditions:

• Selector lever N position
• Emergency switch ON
• Emergency shift switch N position

Does the transmission warning lamp blink in the
IPC?

—

Go to Step 16

Go to Chart 3 of 4

Step 1

1. Apply the brake pedal firmly.
2. Turn the emergency shift switch to 1.

Does the 1st gear engage?

—

Go to Step 17

Go to Chart 3 of 4

Step 13

Step

Action

Value(s)

Yes

Transmission Control System (Smoother) 7A-181

1. Stop the vehicle.
2. Apply the brake pedal firmly.
3. Turn the emergency shift switch to R.

Does the reverse gear engage?

—

Go to Step 18

Go to Chart 3 of 4

Step 24

1. Stop the vehicle.
2. Put the vehicle with the following conditions:

• Selector lever N position
• Emergency switch OFF
• Emergency shift switch N position

3. Turn OFF the ignition for 30 seconds.
4. Turn ON the ignition, with the engine OFF.

Does the gear position display in the IPC indicate
N?

—

System OK

If DTC is set, refer to

applicable DTC.

If no DTC, Go to

Step 19

1. Perform following checks which ever gear

position did not engage or disengage. Use
Tech 2 transmission data list normal reading or
a known good vehicle to determine nominal
values.

2. Visually inspect the gear select position

sensor, gear shift position sensor, select
solenoid valve, 1-3-5 shift solenoid valve, 2-4-
6-R shift solenoid valve for the following
conditions:

• Physical damage
• Loose or improper installation

3. Remove the transmission gearshift control

box. Refer to Repair Instructions (Overhaul) -
Control Box in this section.

4. Visually inspect the gearshift control box for

the following conditions:

• Internal lever damage that connects to the

each position sensor.

• Internal lever damage that connects to the

each solenoid valve.

• Shift lever damage that connects to the

interlock plate and shift rods

• Other damage that the shift lever possible

to stuck.

5. Inspect the transmission main unit as

necessary. Refer to Repair Instructions
(Overhaul) in this section.

6. Remove the oil pump assembly. Refer to

Repair Instructions (Overhaul) - Oil Pump in
this section.

7. Inspect the oil pump assembly and gearshift

clutch for the following conditions:

• The gearshift clutch solenoid valve or lock

up clutch solenoid valve for mechanically
stuck or damage.

• Each spool valve for damage.
• The oil pump for damage.
• ATF Internal leaking
• The gearshift clutch mechanically stuck or

damage.

8. Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 2

—

Step

Action

Value(s)

Yes

7A-182 Transmission Control System (Smoother)

Chart 2 of 4

Does the gear position display in the IPC keep to
indicate N?

—

Go to Step 21

Go to Step 22

Does the transmission warning lamp blink in the
IPC?

—

Go to Chart 3 of 4

Step 9

Go to Step Chart 4 of

4 Step 1

Does the gear position display in the IPC indicate
any gear?

—

If DTC is set, the

TCM is not allowing

auto shift control.

Refer to applicable

DTC.

If no DTC, Go to

Chart 4 of 4 Step 16

Go to Chart 4 of 4

Step 12

Step

Action

Value(s)

Yes

Step

Action

Value(s)

Yes

1. Turn ON the ignition switch, with the engine

OFF.

2. Observe the Economy Switch parameter with

the Tech 2.

Does the Economy Switch parameter indicate ON
when the switch is ON?

—

Go to Step 2

Go to Step 3

Does the ECONO indicator lamp illuminate at Step
1?

—

Go to Intermittent

Conditions

Go to Step 9

1. Turn OFF the ignition.
2. Disconnect the economy mode and 1st gear

start switch harness connector.

3. Turn ON the ignition, with the engine OFF.
4. Observe the Economy Switch parameter with

the Tech 2 while momentarily jumping 3-amp
fused jumper wire between the economy mode
switch harness (pin 6 of N-20 connector) and a
known good ground.

Does the Tech 2 indicate ON when the circuit is
jumpered and OFF when the circuit is not
jumpered?

—

Go to Step 4

Go to Step 5

Observe the Economy Switch parameter with the
Tech 2 while momentarily jumping 3-amp fused
jumper wire across the economy mode switch
harness (pins 3 and 6 of N-20 connector).

Does the Tech 2 indicate ON when the circuit is
jumpered and OFF when the circuit is not
jumpered?

—

Go to Step 7

Go to Step 6

1. Test the economy switch signal circuit

between the transmission control module
(TCM) (pin 13 of B-428 connector) and the
economy mode switch (pin 6 of N-20
connector) for an open circuit or high
resistance.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 8

Repair the open circuit or high resistance on the
ground circuit of the economy mode switch (pin 3 of
N-20 connector) and the chassis ground (B-1).

Did you complete the repair?

—

Go to Step 35

—

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