Isuzu N-Series. Manual - part 932

Transmission Control System (Smoother) 7A-183

1. Turn OFF the ignition.

Inspect for an intermittent and for poor connections
at the harness connector of the economy mode
switch (pins 3 and 6 of N-20 connector).

2. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 32

1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Inspect for an intermittent and for a poor

connection on the economy mode switch
signal circuit at the harness connector of the
TCM (pin 13 of B-428 connector).

4. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 34

1. Turn OFF the ignition.
2. Disconnect the TCM harness connector (B-

425 connector).

3. Turn ON the ignition, with the engine OFF.
4. Connect a 3-amp fused jumper wire between

the ECONO indicator lamp control circuit of the
TCM harness connector (pin 12 of B-425
connector) and a known good ground.

Does the ECONO indicator lamp illuminate?

—

Go to Step 12

Go to Step 10

1. Turn OFF the ignition.
2. Inspect for an intermittent and for a poor

connection at the harness connector of the
instrument panel cluster (IPC) (pin 7 of B-53
connector).

3. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 11

1. Test the ECONO indicator lamp control circuit

between the TCM (pin 12 of B-425 connector)
and the IPC (pin 7 of B-53 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 33

1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Inspect for an intermittent and for a poor

connection on the ECONO indicator lamp
control circuit at the harness connector of the
TCM (pin 12 of B-425 connector).

4. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 34

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 OFF
when the switch is OFF?

—

Go to Step16

Go to Step 14

Step

Action

Value(s)

Yes

7A-184 Transmission Control System (Smoother)

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.

Does the Economy Switch parameter indicate
OFF?

—

Go to Step 32

Go to Step 15

1. Test the economy switch circuit between the

TCM (pin 13 of B-428 connector) and the
economy mode switch (pin 6 of N-20
connector) for a short to ground.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 34

1. Turn OFF the ignition.
2. Disconnect the IPC B-53 connector harness

connector.

3. Connect a test lamp between the ECONO

indicator lamp control circuit (pin 7 of B-53
connector) and battery voltage.

4. Turn ON the ignition, with the engine OFF.

Does the test lamp continuously illuminate (test
lamp blink then go out normally)?

—

Go to Step 17

Go to Step 33

1. Test the ECONO indicator lamp control circuit

between the TCM (pin 12 of B-425 connector)
and the IPC (pin 7 of B-53 connector) for a
short to ground.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 34

1. Turn ON the ignition switch, with the engine

OFF.

2. Observe the 1st gear start switch parameter

with the Tech 2.

Does the 1st gear start switch parameter indicate
ON when the switch is ON?

—

Go to Step 19

Go to Step 20

Does the 1st START indicator lamp illuminate at
Step 18?

—

Go to Intermittent

Conditions

Go to Step 26

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

start switch harness connector.

3. Turn ON the ignition, with the engine OFF.
4. Observe the 1st Gear Start Switch parameter

with the Tech 2 while momentarily jumping 3-
amp fused jumper wire between the economy
switch harness (pin 4 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 21

Go to Step22

Observe the 1st Gear Start Switch parameter with
the Tech 2 while momentarily jumping 3-amp fused
jumper wire across the economy switch harness
(pins 1 and 4 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 24

Go to Step 23

Step

Action

Value(s)

Yes

Transmission Control System (Smoother) 7A-185

1. Test the 1st gear start switch signal circuit

between the TCM (pin 1 of B-427 connector)
and the 1st gear start switch (pin 4 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 25

Repair the open circuit or high resistance on the
ground circuit of the 1st gear start switch (pin 1 of N-
20 connector) and the chassis ground (B-1).

Did you complete the repair?

—

Go to Step 35

—

1. Turn OFF the ignition.
2. Inspect for an intermittent and for poor

connections at the harness connector of the
1st gear start switch (pins 1 and 4 of N-20
connector).

3. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 32

1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Inspect for an intermittent and for a poor

connection on the 1st gear start switch signal
circuit at the harness connector of the TCM
(pin 1 of B-427 connector).

4. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 34

1. Turn OFF the ignition.
2. Inspect for an intermittent and for a poor

connection at the harness connector of the
IPC (pin 6 of B-53 connector).

3. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 27

1. Test the 1st START indicator lamp circuit

between the 1st gear start switch (pin 4 of N-
20 connector) and the IPC (pin 6 of B-53
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 33

1. Turn ON the ignition switch, with the engine

OFF.

2. Observe the 1st Gear Start Switch parameter

with the Tech 2.

Does the 1st Gear Start Switch parameter indicate
OFF when the switch is OFF?

—

Go to Step 31

Go to Step 29

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 1st Gear Start Switch parameter

with the Tech 2.

Does the 1st Gear Start Switch parameter indicate
OFF?

—

Go to Step 32

Go to Step 30

Step

Action

Value(s)

Yes

7A-186 Transmission Control System (Smoother)

Chart 3 of 4

1. Test the 1st gear start switch circuit between

the TCM (pin 1 of B-427 connector) and the 1st
gear start switch (pin 4 of N-20 connector) for
a short to ground.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 34

1. Test the 1st START indicator lamp circuit

between the diode (pin 1 of X-32 connector)
and the IPC (pin 6 of B-53 connector) for a
short to ground.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 35

Go to Step 33

Replace the economy mode & 1st gear start switch.

Did you complete the replacement?

—

Go to Step 35

—

Repair or replace the IPC. Refer to Instrument
Panel Cluster (IPC) Replacement in the Cab and
Chassis Electrical section.

Did you complete the repair or replacement?

—

Go to Step 35

Important:
Replacement TCM must be programmed and
learned.
Replace the TCM. Refer to Transmission Control
Module (TCM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 35

—

Reconnect all previously disconnected fuse or
harness connector(s).

Is the action complete?

—

Go to Chart 1 of 4

Step 6

—

Step

Action

Value(s)

Yes

Step

Action

Value(s)

Yes

1. Turn ON the ignition switch, with the engine

OFF.

2. Observe the Emergency Switch parameter

with the Tech 2.

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

—

Go to Step 2

Go to Step 3

Does the transmission warning lamp blink at Step
1?

—

Go to Intermittent

Conditions

Go to Transmission

Warning Lamp

Inoperative

1. Turn OFF the ignition.
2. Disconnect the emergency switch harness

connector.

3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the voltage feed

circuit of the emergency switch harness (pin 1
of N-17 connector) and a known good ground.

Does the test lamp illuminate?

—

Go to Step 4

Go to Step 5

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