Isuzu N-Series. Manual - part 928

 

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Isuzu N-Series. Manual - part 928

 

 

Transmission Control System (Smoother) 7A-167

21

1. Turn OFF the ignition.
2. Reconnect the ECM harness connectors. 
3. Turn ON the ignition, with the engine OFF.
4. Connect a DMM between the CAN Low circuit

(pin 1 of B-387 connector) and a known good
ground at the resistor 1 harness connector.
Record the voltage reading.

5. Connect a DMM between the CAN High circuit

(pin 2 of B-387 connector) and a known good
ground at the resistor 1 harness connector.
Record the voltage reading

Are both voltage readings within the specified
value?

1.3 - 3.7 volts

Go to Step 34

Go to Step 37

22

1. Test for an open or high resistance in the CAN

Low or High circuit (which ever voltage reading
did not read between 1.3 — 3.7 volts in Step
16) between the DRM and joint connection.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 28

23

1. Test for an open or high resistance in the CAN

Low or High circuit (which ever voltage reading
did not read between 1.3 — 3.7 volts in Step
15) between the TCM and joint connection.

2. Repair the circuit(s) as necessary.
3. Did you find and correct the condition?

—

Go to Step 38

Go to Step 29

24

1. Test for an open or high resistance in the CAN

Low or High circuit (which ever voltage reading
did not read between 1.3 — 3.7 volts in Step
17) between the ECM and joint connection.

2. Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 31

25

Repair the short circuit each other across the CAN
Low and High circuits among the resistor 1, TCM
and EHCU.

Did you complete the repair?

—

Go to Step 38

—

26

Repair the short circuit each other across the CAN
Low and High circuits among the resistor 2, ECM,
DRM and EHCU.

Did you complete the repair?

—

Go to Step 38

—

27

1. Test the CAN Low and High circuits between

the resistor 1 (pins 1 and 2 of B-387 connector)
and the EHCU (pins 14 and 15 of J-177
connector) for an open circuit or high
resistance.

2. Test the CAN Low and High circuits between

the resistor 2 (pins 1 and 2 of B-431 connector)
and the EHCU (pins 26 and 27 of J-177
connector) for an open circuit or high
resistance. 

3. Inspect for an intermittent, for poor

connections and corrosion on the CAN Low
and High circuits at the harness connector of
the each resistor.

4. Repair the circuit(s) or connection(s) as

necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 30

Step

Action

Value(s)

Yes

No

7A-168 Transmission Control System (Smoother)

28

1. Inspect for an intermittent, for poor

connections and corrosion on the CAN Low
and High circuits at the harness connector of
the DRM (pins 2 and 8 of B-429 connector).

2. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 34

29

1. Inspect for an intermittent, for poor

connections and corrosion on the CAN Low
and High circuits at the harness connector of
the TCM (pins 2 and 3 of B-427 connector).

2. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 35

30

1. Inspect for an intermittent, for poor

connections and corrosion on the CAN Low
and High circuits at the harness connector of
the EHCU (pins 14, 15, 26 and 27 of J-177
connector).

2. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 36

31

1. Inspect for an intermittent, for poor

connections and corrosion on the CAN Low
and High circuits at the harness connector of
the ECM (pins 18 and 37 of J-191 connector).

2. Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 38

Go to Step 37

32

Replace the resistor 1.

Did you complete the replacement?

—

Go to Step 38

—

33

Replace the resistor 2.

Did you complete the replacement?

—

Go to Step 38

—

34

Replace the DRM. Refer to Data Recording Module
(DRM) Replacement.

Did you complete the replacement?

—

Go to Step 38

—

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 38

—

36

Replace the EHCU. Refer to Electric Hydraulic
Control Unit (EHCU Replacement in the Anti-lock
Brake section.

Did you complete the replacement?

—

Go to Step 38

—

37

Important:
Replacement ECM must be programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) Replacement /Restore Fuel Injector ID Code
Data in engine control section.

Did you complete the replacement?

—

Go to Step 38

—

Step

Action

Value(s)

Yes

No

Transmission Control System (Smoother) 7A-169

38

1. Reconnect all previously disconnected

harness connector(s).

2. Clear the DTCs with the Tech 2.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 39

39

Observe the DTC Information with the Tech 2. 

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

7A-170 Transmission Control System (Smoother)

U0400 (Flash Code 23)

Circuit Description
The engine speed signal to the transmission control
module (TCM) is sent from the engine control module
(ECM) via a controller area network (CAN)
communication bus based on inputs from the crankshaft
position (CKP) sensor and camshaft position (CMP)
sensor. If the TCM detects no engine speed signal from
the ECM during the engine running, this DTC will set.
Condition for Running the DTC

• The ignition switch is ON.
• The ignition voltage is more than 20 volts.
• The emergency switch is OFF.

Condition for Setting the DTC

• The TCM detects that the engine speed CAN Bus

messages from the ECM are not being received.

Action Taken When the DTC Sets

• The TCM illuminates the transmission warning

lamp when the diagnostic runs and fails.

• The TCM inhibits gear select & shift position

learning and half-clutch learning.

Condition for Clearing the DTC

• The TCM turns OFF the transmission warning

lamp when the diagnostic runs and does not fail.

• A current DTC clears when the diagnostic runs and

does not fail.

• A history DTC clears when the diagnostic runs and

does not fail.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Notice:

• If this DTC is present, the Engine Speed parameter

on the Tech 2 will indicate the turbine speed when
the current gear is neutral or lock up clutch is
engaged. Other condition, it indicates a default
value.

DTC U0400 (Flash Code 23)

Schematic Reference: Transmission Controls
Schematics 
Connector End View Reference: Transmission
Controls Connector End Views or Transmission Control
Module (TCM) Connector End Views

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check -
Transmission Controls?

—

Go to Step 2

Go to Diagnostic 

System Check - 

Transmission 

Controls

2

1. Install the Tech 2.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC)

Information with the Tech 2.

Is DTC U0100 or U0121 set?

—

Go to Applicable 

DTC

Go to Step 3

3

1. Select the “4HK1” in the system selection

menu.

2. Monitor the DTC Information with the Tech 2.

Is the engine control module (ECM) DTC P0335,
P0336, P0340, P0341 or P1345 set?

—

Go to Applicable 

DTC in Engine 

Control Section

Go to Diagnostic 

Aids

 

 

 

 

 

 

 

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