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Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 827

6E–37

3.2L ENGINE DRIVEABILITY AND EMISSIONS

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

Yes

Value(s)

Action

1. Remove the glove box to gain access to the A/C

thermostat.

2. Disconnect the thermostat connector.
3. Attach a fused jumper between ground and the

GRN/RED wire at the thermostat.

4. A/C “ON.”
5. Blower “ON.”

Dose A/C request indicate “YES” on the Tech 2?

—

Go to

Step 16

Go to

Step 23

1. Ignition “ON.”
2. A/C switch “ON”.
3. Use a DVM to check voltage at the electronic A/C

thermostat.

Was voltage equal to the specified value?

B+

Go to

Step 20

Go to

Step 17

Check for an open (LT GRN/BLK) wire between the
thermostat and the A/C switch.

Was the wire open?

—

Go to

Step 18

Go to

Step 19

Repair the open wire (LT GRN/BLK) between the
thermostat and the A/C switch.

Is the action complete?

—

Verify repair

—

Replace the A/C switch.

Is the action complete?

—

Verify repair

—

Use an ohmmeter to check continuity between the
electronic A/C thermostat and the blower switch.

Was there an open circuit?

—

Go to

Step 21

Go to

Step 22

Repair the open wire (WHT) between the thermostat
and the blower switch.

Is the action complete?

—

Verify repair

—

Replace the electronic A/C thermostat.

Is the an action complete?

—

Verify repair

—

Check for an open circuit between A/C thermostat relay
and ECM A/C request terminal (B-31).

Was there an open circuit?

—

Go to

Step 24

Go to

Step 25

Repair the open circuit between the ECM and A/C
thermostat relay.

Is the action complete?

—

Verify repair

—

Check for an open circuit between the engine device
fuse and the A/C thermostat relay (WHT/GRN).

Was there an open circuit?

—

Go to

Step 26

Go to

Step 27

Repair the open circuit between the engine device fuse
and the A/C thermostat relay.

Is the action complete?

—

Verify repair

—

1. Ignition “ON.”
2. Use a DVM to check voltage at the A/C pressure

switch (BRN).

Was voltage equal to the specified value?

B+

Go to

Step 29

Go to

Step 28

6E–38

3.2L ENGINE DRIVEABILITY AND EMISSIONS

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

Yes

Value(s)

Action

Repair the open circuit between the 10A A/C fuse and
the pressure switch.

Is the action complete?

—

Verify repair

—

Use an ohmmeter to check continuity between the
pressure switch and the A/C thermostat relay.

Was the circuit open?

—

Go to

Step 30

Go to

Step 31

Repair the open circuit between the pressure switch
and the A/C thermostat relay.

Is the action complete?

—

Verify repair

—

Check for damaged pin or terminal at the ECM.

Was a damaged pin or terminal found?

—

Go to

Step 32

Go to

Step 33

Repair the damaged pin or terminal.

Is the action complete?

—

Verify repair

—

Replace the ECM.

Is the action complete?

—

Verify repair

—

1. Remove the A/C compressor relay.
2. Ignition “ON.”
3. Use a DVM to check voltage at both of the BRN

wires at the A/C compressor relay socket.

Is the voltage equal to the specified value?

B+

Go to

Step 36

Go to

Step 35

Repair the faulty BRN wire between the A/C fuse and
the A/C compressor relay .

Is the action complete?

—

Verify repair

—

1. A/C compressor relay removed.
2. Engine idling.
3. A/C “ON.”
4. Blower “ON.”
5. Use a DVM to measure voltage between the

GRY/RED wire at the A/C compressor relay socket
and battery+.

Did the DVM indicate the specified value?

B+

Go to

Step 40

Go to

Step 37

Check for an open GRY/RED wire between ECM
terminal B-11 and the A/C compressor relay.

Was the wire open?

—

Go to

Step 38

Go to

Step 39

Repair the open GRY/RED wire between the ECM and
the A/C compressor relay.

Is the action complete?

—

Verify repair

—

Check for a damaged pin or terminal at B-11 of the
ECM.

Was a damaged pin or a terminal found?

—

Go to

Step 32

Go to

Step 33

6E–39

3.2L ENGINE DRIVEABILITY AND EMISSIONS

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

Yes

Value(s)

Action

1. A/C compressor relay removed.
2. Connect a fused jumper at the A/C compressor

relay socket between either BRN wire and the GRN
wire.

3. Engine idling.
4. A/C “ON.”
5. Blower “ON.”

Did the compressor magnetic clutch engage?

—

Go to

Step 41

Go to

Step 42

Repair the A/C compressor relay.

Is the action complete?

—

Verify repair

—

Check for an open circuit between the A/C compressor
relay and the A/C clutch.

Was an open circuit found?

—

Go to

Step 43

Go to

Step 44

Repair the open circuit between the compressor Clutch
and the A/C compressor relay.

Is the action complete?

—

Verify repair

—

Service the compressor clutch or replace the
compressor due to a faulty internal overheat switch.

Is the action complete?

—

Verify repair

—

1. Remove the A/C compressor relay.
2. Idle the engine.

Is the compressor clutch still engaged when A/C is not
selected?

—

Go to

Step 46

Go to

Step 47

Repair the short to voltage between the A/C clutch and
A/C compressor relay.

Is the action complete?

—

Verify repair

—

1. Reinstall the A/C compressor relay.
2. Remove the A/C thermostat relay.
3. Engine idling.

Is the compressor clutch still engaged when A/C is not
selected?

—

Go to

Step 48

Go to

Step 50

Use a DVM to check for a short to ground between the
A/C compressor relay and B-11 of the ECM.

Was a short detected?

—

Go to

Step 49

Go to

Step 33

Repair the short to ground between the ECM and A/C
compressor relay.

Is the action complete?

—

Verify repair

—

Repair the short to ground between the A/C thermostat
relay and the electronic thermostat.

Is the action complete?

—

Verify repair

—

6E–40

3.2L ENGINE DRIVEABILITY AND EMISSIONS

Electronic Ignition System Diagnosis

If the engine cranks but will not run or immediately stalls,
the Engine Cranks But Will Not Start chart must be used
to determine if the failure is the ignition system or the fuel
system. If DTC P0341, or P0336 is set, the appropriate
diagnostic trouble code chart must be used for diagnosis.
If a misfire is being experienced with no DTC set, refer to
the

Symptoms section for diagnosis.

Visual Check of The Evaporative

Emission Canister

If the canister is cracked or damaged, replace the
canister.

If fuel is leaking from the canister, replace the canister
and check hoses and hose routing.

Fuel Metering System Check

Some failures of the fuel metering system will result in an
“Engine Cranks But Will Not Run” symptom. If this
condition exists, refer to the

Engine Cranks But Will Not

Run chart. This chart will determine if the problem is
caused by the ignition system, the ECM, or the fuel pump
electrical circuit.
Refer to

Fuel System Electrical Test for the fuel system

wiring schematic.
If there is a fuel delivery problem, refer to

Fuel System

Diagnosis, which diagnoses the fuel injectors, the fuel
pressure regulator, and the fuel pump. If a malfunction
occurs in the fuel metering system, it usually results in
either a rich HO2S signal or a lean HO2S signal. This
condition is indicated by the HO2S voltage, which causes
the ECM to change the fuel calculation (fuel injector pulse
width) based on the HO2S reading. Changes made to the
fuel calculation will be indicated by a change in the long
term fuel trim values which can be monitored with a Tech
2. Ideal long term fuel trim values are around 0%; for a
lean HO2S signal, the ECM will add fuel, resulting in a fuel
trim value above 0%. Some variations in fuel trim values
are normal because all engines are not exactly the same.
If the evaporative emission canister purge is “ON,” the
long term fuel trim may be as low as –38%. If the fuel trim
values are greater than +23%, refer to

DTC P0131,DTC

P0171, and DTC 1171 for items which can cause a lean
HO2S signal.

Idle Air Control (IAC) Valve

The Tech 2 displays the IAC pintle position in counts. A
count of “0” indicates the ECM is commanding the IAC
pintle to be driven all the way into a fully-seated position.
This is usually caused by a large vacuum leak.
The higher the number of counts, the more air is being
commanded to bypass the throttle blade. Refer to IAC
System Check in order to diagnose the IAC system.
Refer to

Rough, Unstable, or Incorrect Idle, Stalling in

Symptoms for other possible causes of idle problems.

Fuel System Pressure Test

A fuel system pressure test is part of several of the
diagnostic charts and symptom checks. To perform this
test, refer to

Fuel Systems Diagnosis.

Fuel Injector Coil Test Procedure and

Fuel Injector Balance Test Procedure

T32003

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Relieve the fuel pressure by connecting the

5–8840–0378–0 Fuel Pressure Gauge to the fuel
pressure connection on the fuel rail.

CAUTION: In order to reduce the risk of fire and
personal injury, wrap a shop towel around the fuel
pressure connection. The towel will absorb any fuel
leakage that occurs during the connection of the fuel
pressure gauge. Place the towel in an approved
container when the connection of the fuel pressure
gauge is complete.

Place the fuel pressure gauge bleed hose in an
approved gasoline container.
With the ignition switch “OFF,” open the valve on the
fuel pressure gauge.

3. Record the lowest voltage displayed by the DVM

after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)

Injector Specifications:

Resistance Ohms

Voltage Specification at

C-35

C (50

F-95

11.8 – 12.6

5.7 – 6.6

The voltage displayed by the DVM should be within
the specified range.

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