Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 350

6E–430

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnosis Trouble Code(DTC) 

P1221 TPS1 – TPS2 Correlation(Circuit Performance)

060R200069

Circuit Description

D

The powertrain control module (PCM) controls engine
speed by adjusting the position of the throttle control
valve (DC motor). The throttle motor is a DC motor
driven by one coil. The PCM applies current to  DC
motor coil in duty (%) to adjustment the  valve into a
passage in the throttle body to air flow.
This method allows highly accurate control of engine
speed and quick response to changes in engine
load.

D

The accelerator position (AP) sensor circuit provides a
voltage signal relative to accelerator pedal angle.
The accelerator pedal angle (AP1) will vary from
about 13% at idle position to about 87% at open
throttle(WOT).

APS signal is used to determine which DC will adjust
throttle position.

After the APS signal has been processed by the
PCM, it will command the DC motor to move the
throttle position.

D

Accelerator pedal – Check for objects blocking the AP
sensor or pedal arm with spring, and excessive
deposits in the accelerator pedal arm and on the
accelerator pedal.

Conditions for Setting the DTC

D

The ignition is “ON”.

D

A difference of between TPS1 and TPS2 correlation of
over 6.5% within 125 milliseconds.

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.

Condition for Clearing the MIL/DTC

D

A history DTC 1221 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

D

DTC 1221 can be cleared using the Tech 2 “Clear Info”
function or by disconnecting the PCM battery feed.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Visually/physically inspect for the following throttle

valve conditions.

3.Visually/physically inspect for the following

accelerator pedal conditions.

5.Check the following circuits for throttle valve and DC

moter. Check the following TP sensor resistance
and DC motor.

6E–431

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

7.Check the following circuits for accelerator pedal

problems. Check the following AP sensor
resistance.

9.Following DTC: Software detect Error for ETC

system.

10.Following DTC: Software detect Error for ETC

system.

Diagnostic Aids

D

An intermittent may be caused by a poor connection,
rubbed–through wire insulation or a wire broken inside

the insulation. Check for poor connections or a
damaged harness. Inspect the PCM harness and
connector for improper mating, broken locks,
improperly formed or damaged terminals, poor
terminal-to-wire connection,

and 

damaged

harness.

D

Throttle body – Check for objects blocking the DC
motor or throttle bore, excessive deposits in the ETC
passage and on the valve spring, and excessive
deposits in the throttle bore and on the throttle valve
plate.

Diagnosis Trouble Code(DTC) 

P1221 TPS1 – TPS2 Correlation(Circuit 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

Visually/physically inspect for the following conditions:

D

Throttle body tampering.

D

Restricted intake throttle system. Check for a
possible  collapsed air intake duct, restricted air
filter  element, or foreign objects blocking the air
intake  system.

D

Throttle body: Check for objects blocking the
throttle  passage or throttle bore, excessive
deposits in  the throttle passage and on the
throttle valve, and  excessive deposits in the
throttle bore and on the  throttle plate.

D

Throttle body with lever: Check for objects send
round  the throttle spring lever that lever is smooth
movement,  and spring lever has not excessive
play

Do any of the above require a repair?

—

Refer to

appropriate

section for

on–vehicle

service

Go to 

Step 4

4

Visually/physically inspect for the following conditions:

D

Accelerator pedal tampering.

D

Accelerator pedal : Check for objects blocking the
spring or pedal arm.

D

Accelerator pedal : Check for objects move the
accelerator pedal that pedal is smooth
movement, and accelerator pedal arm has not
excessive play.

Do any of the above require a repair?

—

Refer to

appropriate

section for

on–vehicle

service

Go to 

Step 5

5

1.  Check for a poor connection at the throttle body

harness connector.

2.  Check for a poor connection at the accelerator

position sensor harness connector.

3.  If a problem is found, replace faulty terminals as

necessary.

Was a problem found?

—

Verify repair

Go to 

Step 6

6E–432

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnosis Trouble Code(DTC) 

P1221 TPS1 – TPS2 Correlation(Circuit Performance)

  (Cont'd)

Step

No

Yes

Value(s)

Action

6

1. Check the following circuits for an open, short to

voltage, short to ground, or poor connection at the
PCM:

Throttle position sensor 1 circuit.

Throttle position sensor 2 circuit.

Throttle DC motor circuit.

Throttle position sensor resistance.

Throttle DC motor  resistance.

2. If a problem is found, repair as necessary.

Was a problem found?

Vcc-GND

1–7k

W

SIG-GND

change

resistance 0.3

– 100

W

Verify repair

Go to 

Step 7

7

1. Check the following circuits for an open, short to

voltage, short to ground, or poor connection at the
PCM:

D

Accelerator position sensor 1 circuit.

D

Accelerator position sensor 2 circuit.

D

Sensor 3 circuit.

D

Sensor resistance.

2. If a problem is found, repair as necessary.

Was a problem found?

Vcc-GND

1–7k

W

SIG-GND

change

resistance 0.3

– 100

W

Verify repair

Go to 

Step 8

8

Replace the accelerator position sensor.

Is the action complete?

—

Go to 

Step 9

—

9

Stored DTCs;
P1125, P1290, P1295, P1299

—

Go to

applicable
DTC table

Go to 

Step 10

10

Stored DTCs;
P1514, P1515, P1516, P1523, P1271, P1272, P1273

—

Go to

applicable
DTC table

Go to 

Step 11

11

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 replacement PCM.

Is the action complete?

—

Verify repair

—

6E–433

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1271  APS 1– 2  Correlation Error

060R200064

Circuit Description

D

The accelerator position (AP) sensor circuit provides a
voltage signal relative to accelerator pedal angle.
The accelerator pedal sensor (AP1) will vary from
about 13 % at idle position to about 87 % at wide
open throttle(WOT) to specified voltage (about 5V).

This code detects a correlation error between APS1
and APS2.

Conditions for setting the DTC

D

The Ignition is “ON”.

D

The accelerator pedal angle difference is more than 4.5
% between ASP1 and APS2 for more than 265
milliseconds.

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 MIL/DTC

D

The PCM will turn the MIL “OFF” on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.

D

A history DTC P1271 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

D

DTC P1271 can be cleared using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

An intermittent may be caused by the following:

D

Poor connections.

D

Mis routed harness.

D

Rubbed through wire insulation.

D

Broken wire inside the insulation.

Check for the following conditions:

D

Poor connection at PCM-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. If the harness appears to be OK, observe the
AP sensor 1, AP sensor 2 display on the Tech 2 while
moving connectors and wiring harnesses related to the
sensor.
A change in the display will indicate the location of
the fault. If DTC P1271 cannot be duplicated, the
information included in the Failure Records data can
be useful in determined vehicle mileage since the
DTC was last set.

If it is determined that the DTC occurs intermittently,
performing the DTCP1271 Diagnostic Chart may
isolate the cause of the fault.