Isuzu Rodeo UE. Manual — part 171

6E1–55

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

On–Board Diagnostic (OBD II) System Check

(Cont'd)

Step

No

Yes

Value(s)

Action

9

1. Attempt to reprogram the PCM. Refer to Powertrain

Control Module (PCM) in On–Vehicle Service.

2. Attempt to display PCM data with the Tech 2.

Does the Tech 2 display PCM engine data?

—

Go to

Step 2

Go to

Step 10

10

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed. Refer to Powertrain Control Module
(PCM) in On–Vehicle Service.

And also refer to latest service bulletin
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.

Is the action complete?

—

Verify repair

—

6E1–56

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

A/C CLUTCH CONTROL CIRCUIT DIAGNOSIS

D06RX037

Circuit Description

When air conditioning and blower fan are selected, and if
the system has a sufficient refrigerent charge, a 12–volt
signal is supplied to the A/C request input of the
powertrain control module (PCM). The A/C request signal
may be temporarily cancelled during system operation by
the electronic thermostat in the evaporator case. The
electronic thermostat may intermittently remove the
control circuit ground for the A/C thermostat relay to
prevent the evaporator from forming ice. When the A/C
request signal is received by the PCM, the PCM supplies
a ground from the compressor clutch relay if the engine
operating conditions are within acceptable ranges. With
the A/C compressor relay energized, battery voltage is
supplied to the compressor clutch coil.
The PCM will enable the compressor clutch to engage
whenever A/C has been selected with the engine running,
unless any of the following conditions are present:

f

The throttle is greater than 90%.

f

The ignition voltage is below 10.5 volts.

f

The engine speed is greater than 4500 RPM for 5
seconds or 5400 RPM.

f

The engine coolant temperature (ECT) is greater
than 125

°

C (257

°

F)

f

The intake air temperature (IAT) is less than 5

°

C

(41

°

F).

f

The power steering pressure switch signals a high
pressure condition position.

Diagnostic Aids

To diagnose an intermittent fault, check for the following
conditions:

f

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

6E1–57

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

f

Damaged harness – Inspect the wiring harness for
damage; shorts to ground, shorts to battery voltage,
and open circuits. If the harness appears to be OK,
observe the A/C clutch while moving connnectors and
wiring harnesses related to the A/C. A sudden clutch
malfunction will indicate the source of the intermittent.

A/C Clutch Diagnosis

This chart should be used for diagnosing the electrical
portion of the A/C compressor clutch circuit. A Tech 2 will

be used in diagnosing the system. The Tech 2 has the
ability to read the A/C request input to the PCM. The Tech
2 can display when the PCM has commended the A/C
clutch ON. The Tech 2 should have the ability to override
the A/C request signal and energize the A/C compressor
relay.

A/C Clutch Control Circuit Diagnosis

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,

then clear the DTCs.

3. Operate the vehicle within the Failure Records

conditions as noted.

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

P1546.

Does the Tech 2 indicate DTC P1546 ”Ran and
Passed”?

—

Refer to

Diagnostic

Aids

Go to

Step 3

3

1. Ignition OFF.
2. Remove the A/C Compressor Relay from the

Underhood Electrical Center.

3. Ignition ON, engine OFF.
4. Using a Digital Voltmeter (DVM), check for voltage

on the Fused pins of the A/C Compressor Clutch
Relat connector.

Does the DVM read the following value?

12 Volts

Go to

Step 5

Go to

Step 4

4

Check the suspect circuit(s) between the A/C
Compressor Clutch Relay connector and the Fuse for
the following conditions:

f

A short to ground

f

An open circuit

f

A short to voltage

Was the problem found?

—

Verify repair

—

5

1. Ignition OFF.
2. Disconnect the Powertrain Controlm Module (PCM)

connectors from the PCM.

3. Check the A/C Compressor Clutch Relay control

circuit between the PCM and Underhood Electrical
Center for the following conditions:

f

A short to ground

f

An open circuit

f

A short to voltage

Was the problem found?

—

Verify repair

Go to

Step 6

6E1–58

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

No

Yes

Value(s)

Action

6

1. Reinstall the A/C Compressor Clutch Relay.
2. Using a fused jumper, ground the A/C Compressor

Clutch Relay control circuit at the PCM connector.

3. Ignition ON, engine OFF.

Does the A/C Compressor turn ON?

—

Go to

Step 9

Go to

Step 7

7

1. Ignition OFF.
2. Check the A/C Compressor Clutch circuit between

the A/C Compressor Clutch Relay and A/C
Compressor Clutch for the following conditions:

f

A short to ground

f

An open circuit

f

A short to voltage

Was the problem found?

—

Verify repair

Go to

Step 8

8

Replace the A/C Compressor Clutch Relay.

Is the action complete?

—

Verify repair

—

9

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.Refer to On–Vehicle Service in
Powertrain Control Module and Sensors for
procedures.

And also refer to latest service bulletin
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.

Verify repair.

—

—

—