Isuzu Trooper (1998-2002 year). Manual - part 516

6E–434

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

If it is determined that the DTC occurs intermittently,
performing the DTC P1523 Diagnostic Chart may
isolate the cause of the fault.

DTC P1523 - Actuator Control Return Performance

 

Step

Action

Value(s)

Yes

No

1

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

—

Go to

 Step 2

Go to

 OBD

System

Check

2

Was the “Electric Throttle Control (ETC) System
Check” performed?

—

Go to 

Step 3

Go to 

ETC

System

Check

3

1. Warming up the engine until the ECT rise at 80

°

C

2. Ignition “OFF”.
3. Ignition “ON” but not engine run.
4. Observe the TP angle reading on the Tech 2 while

alowly opening the throttle.

NOTE: The value check of TPS must be performed in
less than 15 seconds.

Does the TP angle increase steadily and evenly from
the closed throttle value to the wide open throttle
value?

Closed

throttle
TPS1=
6

∼

12%

TPS2=

88

∼

94% Wide

open throttle

TPS1=

79

∼

83%

TPS2=

19

∼

23%

Go to

 Step 7

Go to

 Step 4

4

1. Ignition “OFF.”
2. Disconnect the DC motor.

Is the DC motor reading near the specified value?

0.3 

∼

 100 

W

Go to

 Step 5

Go to

 Step 6

5

1. Check the DC motor harness between the PCM and

DC Motor circuit at the DC motor harness
connector.

2. If a problem is found, repair wiring harness as

necessary.

Was a problem found?

—

Verify repair

Go to

 Step 8

6

Replace the throttle assembly (DC motor).

Is the action complete?

—

Verify repair

Go to

 Step 5

7

Was the DTC P1523 stored?

—

Go to

 Step 12

Check the

procedure.

Refer to

Diagnostic

Aids

8

1. Connect a DVM between the 5Volt reference circuit

and the TP1 and TP2 sensor ground circuit at the
TP sensor harness connector.

2. Observe the voltage using a DVM.

Is the voltage near the specified value?

5V

Go to

 Step 9

Go to

 Step 10

9

Check the following items;

1. TP1 and TP2 signal circuit for a short to voltage.
2. TP1 and TP2 sensor ground circuit for high

resistance between the PCM and the TP sensor.

3. TP1and TP2 sensor ground circuit for a poor

connection.

4. If a problem is found, repair wiring harness as

necessary.

Was a problem found?

—

Verify repair

Go to

 Step 10

6E–435

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P1523 - Actuator Control Return Performance

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

Check the following items;

1. TP1and TP2 signal circuit or 5 volt reference circuit

for a poor connection.

2. TP1 and TP2 signal circuit or 5 volt reference circuit

for high resistance between the PCM and the
TP1and TP2 sensor.

3. If a problem is found, repair wiring harness as

necessary.

Was a problem found?

—

Verify repair

Go to

 Step 11

11

Replace the TP sensor.

Was a problem found?

—

Verify repair

—

12

Replace the PCM.

IMPORTANT:
The replacement PCM must be programmed. Refer to
ON-Vehicle Service in Power 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 replasement PCM.

Is the action complete?

—

Verify repair

—

6E–436

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1574 Brake Switch No Operation

D06R200076

Circuit Description

The brake switch has 3 functions.

D

Brake pedal operation check

D

Brake light operation (On and off)

D

Cruise control (Cancel)

The PCM receives vehicle speed and switch position
signals from the brake switch. The PCM sets brake
operating conditions in response to these signals.
If the brake switch is on, the brake system is in normal
operation (cruise control cancelled).

Conditions for Setting the DTC

D

Two break switch signals do not acknowledge after
signal changed.

D

Switch does not change during accelerating vehicle or
decelerating.

D

VSS is not fault.

D

Engine is running.

Action Taken When the DTC Sets

D

The PCM will not turn the malfunction indicator lamp
(MIL) “ON”.

D

The PCM will store conditions which were present
when the DTC was set as Failure Records only.  This
information will not be stored as Freeze Frame data.

Conditions for Clearing the DTC

D

DTC P1574 can be cleared by using the scan tool
“Clear Info” function or by disconnecting the PCM
battery feed.

Diagnostic Aids

D

Damaged harness–Inspect the wiring harness for
damage.  If the harness appears to be OK, observe the
fuel level display on the scan tool while moving
connectors and wiring harnesses related to the sensor.
A change in the display will indicate the location of the
fault.

6E–437

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P1574 Brake Switch No Operation

 

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 “Off”. Engine “Off”.
2. Check following fuses.

D

BACK 15A

D

STOP LAMP 15A

3. If a problem found repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 3

3

1. Make adjustment to the brake switch.

(Refer to 

“Brake switch” in “10A CRUISE

CONTROL SYSTEM”.)

2. If a problem found repair as necessary.

Was the problem found?

—

Verify repair

Go to 

Step 4

4

1. Push the shaft on brake switch.
2. Check shaft operation for smooth movement.
3. If a problem found repair as necessary.

Was the problem found?

—

Verify repair

Go to 

Step 5

5

1. Disconnect the connector at brake switch.
2. Check following terminal pin by ohmmeter.

(Leave the shaft position at brake switch. Don’t
push it.)

D

Between pin 1 and pin 2

D

Between pin 3 and pin 4

Was it specified value?

Between pin1

and pin2 is

0

W

,  Between

pin3 and pin4

is 

∞

W

Go to 

Step 6

Go to 

Step 9

6

1. Disconnect the connector at brake switch.
2. Check following terminal pin at ohmmeter.

(Don’t press the button of the brake switch.)

D

Between pin 1 and pin 2

D

Between pin 3 and pin 4

Was it specified value?

Between pin1

and pin2 is

∞

W

,  Between

pin3 and pin4

is 0

W

Go to 

Step 7

Go to 

Step 9

7

1. Probe related circuits for open or short to ground.
2. If a problem was found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 8

8

1. 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.

Was the action completed?

—

Verify repair

—

9

1. Replace the brake switch.

Was the action completed?

—

Verify repair

—