Isuzu N-Series. Manual - part 935

Transmission Control System (Smoother) 7A-195

Intermittent Conditions

Checks

Action

DEFINITION:
The problem is not currently present but is indicated in DTC History.
OR
There is a customer complaint, but the symptom cannot currently be duplicated, if the problem is not DTC related.

Preliminary Checks 

• Refer to Symptoms - Transmission Controls before starting.

Harness/Connector

Many intermittent open or shorted circuits are affected by harness/connector 
movement that is caused by vibration, engine torque, bumps/rough pavement, etc. 
Test for this type of condition by performing the applicable procedure from the 
following list:

• Move related connectors and wiring while monitoring the appropriate Tech 2 

data.

• Move related connectors and wiring with the component commanded ON, and 

OFF, with the Tech 2. Observe the component operation. 

• With the engine running, move related connectors and wiring while monitoring 

engine operation.

If harness or connector movement affects the data displayed, component/system 
operation, or engine operation, inspect and repair the harness/connections as 
necessary.
Refer to Electrical Connections or Wiring.

Electrical Connections or Wiring

Poor electrical connections, terminal tension or wiring problems cause most 
intermittent. To perform the following inspections:

• Inspect for poor mating of the connector halves, or terminals improperly seated 

in the connector body.

• Inspect for improperly formed or damaged terminals. Test for poor terminal 

tension.

• Inspect for poor terminal to wire connections including terminals crimped over 

insulation. This requires removing the terminal from the connector body.

• Inspect for corrosion/water intrusion. Pierced or damaged insulation can allow 

moisture to enter the wiring. The conductor can corrode inside the insulation, 
with little visible evidence. Look for swollen and stiff sections of wire in the 
suspect circuits.

• Inspect for wires that are broken inside the insulation.
• Inspect the harness for pinched, cut or rubbed through wiring.
• Ensure that the wiring does not come in contact with hot exhaust components.

Control Module Power and Grounds
Component Power and Grounds

Poor power or ground connections can cause widely varying symptoms.

• Test all control module power supply circuits. Many vehicles have multiple 

circuits supplying power to the control module. Other components in the system 
may have separate power supply circuits that may also need to be tested. 
Inspect connections at the module/component connectors, fuses, and any 
intermediate connections between the power source and the module/
component. A test lamp or a DMM may indicate that voltage is present, but 
neither tests the ability of the circuit to carry sufficient current. Ensure that the 
circuit can carry the current necessary to operate the component.

• Test all control module ground and system ground circuits. The control module 

may have multiple ground circuits. Other components in the system may have 
separate grounds that may also need to be tested. Inspect grounds for clean and 
tight connections at the grounding point. Inspect the connections at the 
component and in splice packs, where applicable. Ensure that the circuit can 
carry the current necessary to operate the component.

7A-196 Transmission Control System (Smoother)

Temperature Sensitivity

• An intermittent condition may occur when a component/connection reaches 

normal operating temperature. The condition may occur only when the 
component/connection is cold, or only when the component/connection is hot.

• If the intermittent is related to heat, review the data for a relationship with the 

following:
- High ambient temperatures
- Underhood/engine generated heat
- Circuit generated heat due to a poor connection, or high electrical load
- Higher than normal load conditions, towing, etc.

• If the intermittent is related to cold, review the data for the following: 

- Low ambient temperatures - In extremely low temperatures, ice may form in a 
connection or component. Test for water intrusion.
- The condition only occurs on a cold start.
- The condition goes away when the vehicle warms up.

• Information from the customer may help to determine if the trouble follows a 

pattern that is temperature related.

Electromagnetic Interference (EMI) and 
Electrical Noise

Some electrical components/circuits are sensitive to EMI or other types of electrical 
noise. Inspect for the following conditions:

• A misrouted harness that is too close to high voltage/high current devices such 

as injection components, motors, generator etc. These components may induce 
electrical noise on a circuit that could interfere with normal circuit operation.

• Electrical system interference caused by a malfunctioning relay, or the 

transmission control module (TCM) driven solenoid or switch. These conditions 
can cause a sharp electrical surge. Normally, the problem will occur when the 
malfunctioning component is operating.

• Improper installation of non-factory or aftermarket add on accessories such as 

lights, 2-way radios, amplifiers, electric motors, remote starters, alarm systems, 
cell phones, etc. These accessories may lead to an emission related failure while 
in use, but do not fail when the accessories are not in use. 

• Test for any open diodes. Some relays may contain a clamping diode.
• Test the generator for a bad rectifier bridge that may be allowing AC noise into 

the electrical system.

Duplicating Failure Conditions

• If none of the previous tests are successful, attempt to duplicate and/or capture 

the failure conditions.

• An alternate method is to drive the vehicle with the DMM connected to a 

suspected circuit. An abnormal reading on the DMM when the problem occurs, 
may help you locate the problem.

Tech 2 Snapshot

The Tech 2 can be set up to take a Snapshot of the parameters available via serial 
data. The Snapshot function records live data over a period of time. The recorded 
data can be played back and analyzed. The Tech 2 can also graph parameters 
singly or in combinations of parameters for comparison. The Snapshot can be 
triggered manually at the time the symptom is noticed, or set up in advance to 
trigger when a DTC sets. 
An abnormal value captured in the recorded data may point to a system or 
component that needs to be investigated further.
Refer to the Tech 2 user instructions for more information on the Snapshot function.

Checks

Action

Transmission Control System (Smoother) 7A-197

Programming and Learning

Programming and Learning Guideline

Description

The vehicle information data must be programmed and
the learning procedure must be done when the
transmission control module (TCM) is replaced,
sensors, actuators or internal parts are replaced or
repaired. Programming with the wrong data or improper
learning will cause a deterioration of the shift feeling, the
poor vehicle performance and the diagnostic trouble
code (DTC) to set.
Vehicle Information Programming and/or Initial Learning
must be done whenever any of the following parts is
replaced or specification changed. Refer to
Transmission Control Module (TCM) Replacement -
TCM Replacement Procedure Description in this
section.

• TCM
• Transmission assembly
• Engine type
• Final gear and tire size change relating

speedometer driven gear

• PTO request engine speed

Transmission Gear Select & Shift Position Learning
must be done whenever any of the following parts are
replaced, removed or repaired.

• 1-3-5 shift solenoid valve
• 2-4-6-R shift solenoid valve
• Select solenoid valve
• Gear shift position sensor
• Gear select position sensor
• Transmission gearshift control box
• Transmission unit internal

Half Clutch Position Learning must be done whenever
any of the following parts are replaced, removed or
repaired.

• Gearshift clutch assembly
• Gearshift clutch solenoid valve
• Oil  pump  assembly
• Clutch engagement point is shifted greatly (when

difficult to adjust by the adjustment switch)

Transmission Gear Select & Shift Position
Learning

1. Put the vehicle with the following conditions:

• DTC is not present
• Vehicle is stationary
• Parking brake is pulled
• Selector lever is Neutral
• Emergency switch is OFF
• Engine is idle speed

• Idle up control knob to the lowest position (Full

counterclockwise direction)

• A/C switch is OFF
• Use the Tech 2 and make sure clutch fluid

temperature is 40

°C (104°F) or higher

2. Depress and hold the brake pedal.

Notice:
DO NOT release the brake pedal until the transmission
gear select & shift position learning is completed.

3. Press Reset switch for at least 7 seconds and

release it within 17 seconds. This will enter the
learning mode, which is indicated by a buzzer
pattern that consists of a series of two short beeps.

Notice:
If the buzzer does not sound, restart the learning
procedure from step 1.

4. With the brake pedal firmly depressed, operate the

selector lever in the following sequence: N - D - N
(Neutral - Drive - Neutral)
This will change the buzzer pattern that consists of
a series of two beeps, one short beep followed by
one long beep. After the selector lever is operated,
this buzzer pattern will continue for approximately
10 seconds and shift to each gear will be
automatically performed.

Notice:
If the buzzer does not sound, operate the selector lever
again.

5. Confirm that the buzzer stops.

Half Clutch Position Learning

1. Put the vehicle with the following conditions:

• DTC is not present
• Vehicle is stationary
• Parking brake is pulled
• Selector lever is Neutral
• Emergency switch is OFF
• Engine is warm upped
• Engine is idle speed
• Idle up control knob to the lowest position (Full

counterclockwise direction)

• A/C switch is OFF
• Use the Tech 2 and make sure clutch fluid

temperature is 40

°C (104°F) or higher

2. Depress and hold the brake pedal.

Notice:
DO NOT release the brake pedal until the half clutch
position learning is completed.

7A-198 Transmission Control System (Smoother)

3. Press Reset switch for at least 7 seconds and

release it within 17 seconds. This will enter the
learning mode, which is indicated by a buzzer
pattern that consists of a series of two short beeps.

Notice:
If the buzzer does not sound, restart the learning
procedure from step 1.

4. With the brake pedal firmly depressed, operate the

selector lever in the following sequence: N - D
(Neutral - Drive)
This will change the buzzer pattern that consists of
a series of single short beeps. After the selector
lever is operated, this buzzer pattern will continue
for approximately 30 seconds and the clutch will be
automatically engaged.

Notice:
If the buzzer does not sound, operate the selector lever
again.

5. Confirm that the buzzer stops.