Isuzu Trooper (1998-2002 year). Manual - part 630

6E–168

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0654 (Flash DTC 27)

 Tachometer Circuit Open/Short

060RW136

Circuit Description

The Tach Meter circuit receives through Meter 10A fuse
from the battery, current flowing in the order of Mater and
the Tach Meter.

Action Taken When the DTC Sets

D

The ECM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

D

The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

Conditions for Clearing the MIL/DTC

D

DTC P0650 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the ECM battery
feed.

Diagnostic Aids

Check for the following conditions:

D

Poor connection at ECM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

D

Damaged harness – Inspect the wiring harness for
damage.

D

If the Tech 2 indicat DTCs 0654, P0650 and P0381,
Check the meter circuit necessarily.

6E–169

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

DTC P0654 – Tachometer Circuit Open/Short

 

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to 

Step 2

Go to 

OBD

System

Check

2

1. Ignition “ON,” engine “OFF.”
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor the “DTC” info for DTC

P654.

Does the Tech 2 indicate DTC P0654 failed?

—

Go to 

Step 3

Refer to

Diagnostic

Aids

3

Check the Tach meter circuit for a poor connection at
the Meter and replace the terminal if necessary.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 4

4

Using the Tech 2.

Does the Tech 2 indicate DTC P0654 failed?

—

Verify repair

Go to 

Step 5

5

Check the Tach Meter circuit for a poor connection.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 6

6

Replace the tachometer.

Is the action complete?

—

Verify repair

Go to 

Step 7

7

Replace the ECM (Refer to the Data Programming in
Case of ECM change).

Is the action complete?

—

Verify repair

—

6E–170

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1655 (Flash DTC 17) 

Thermo Relay Circuit Open/Short

060RW130

Circuit Description

The thermo relay circuit receives current through air con
10A fuse from the battery, current flowing in the order of
the thermo relay and thermo SW.

Action Taken When the DTC Sets

D

The ECM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

D

The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

Conditions for Clearing the MIL/DTC

D

DTC P1655 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the ECM battery
feed.

Diagnostic Aids

Check for the following conditions:

D

Poor connection at ECM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

D

Damaged harness – Inspect the wiring harness for
damage.

6E–171

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

DTC P1655 – Thermo Relay Circuit Open/Short

 

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to 

Step 2

Go to 

OBD

System

Check

2

1. Ignition “ON,” engine “OFF.”
2. Observe the “Batteri Voltage” display on the Tech 2.

Is the “Batteri Voltage” below the specified value?

11 V

Go to 

Step 4

Go to 

Step 3

3

1. Ignition “ON,” engine “OFF.”
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor the “Specific DTC” info for

DTC P1655.

Does the Tech 2 indicate DTC P1655 failed?

—

Go to 

Step 4

Refer to

Diagnostic

Aids

4

Check the Thermo Relay circuit for a poor connection
and replace the terminal if necessary.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 5

5

Check the Thermo Relay for damage.

Did the Thermo Relay require replacement?

—

Verify repair

Go to 

Step 6

6

Check the Thermo Relay circuit for a poor connection
at the ECM and replace the terminal if necessary.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 7

7

Replace the ECM (Refer to the Data Programming in
Case of ECM change).

Is the action complete?

—

Verify repair

—