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Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 156

6E–228

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE 1)

(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR CIRCUIT HIGH

INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE 7)

(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR VOLTAGE SUPPLY

CIRCUIT HIGH INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE 9)

(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR VOLTAGE SUPPLY

CIRCUIT LOW INPUT

DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE D)

(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR BRAKE SWITCH

ERROR

DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE E)

(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR IDLE POSITION

SWITCH ERROR

0.5
BLK

0.5
GRN/
BLK

0.5
RED

0.5
WHT

0.5
BLK

2.0
BLK

0.5
BLK/
PNK

0.5
GRY

ECT

Sensor

TPS &

Idle SW

0.5
WHT

101

0.5
RED

CKP

Sensor

Engine
Control
Module
(ECM)

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

6E–229

Condition for setting the DTC and action taken when the DTC sets

Circuit Description

The TPS is a potentiometer connected to throttle shaft
on the throttle body. It is installed to the main TPS and
idle switch.
The engine control module (ECM) monitors the voltage
on the signal line and calculates throttle position. As the
throttle valve angle is changed when accelerator pedal
moved. The TPS signal also changed at a moved
throttle valve. As the throttle valve opens, the output
increases so that the output voltage should be high.
The ECM monitors the TPS supply voltage and TPS
output voltage. The supply voltage is out of range, DTC
P1120 (Symptom Code 7) or P0100 (Symptom Code 9)
will be stored. The output voltage excessively high, DTC
P1120 (Symptom Code 1) will be stored.
If the brake pedal is depressed during accelerator pedal
is depressing, DTC P1120 (Symptom Code D) will be
stored.
If the relation of idle switch and TPS position are
incorrect, DTC P1120 (Symptom Code E) will be stored.

Diagnostic Aids

An intermittent may be caused by the following:

• Poor connections.

• Misrouted harness.

• Rubbed through wire insulation.

• Broken wire inside the insulation.
Check for the following conditions:

• 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.

• Damaged harness-Inspect the wiring harness for

damage. If the harness appears to be OK, observe
the “Throttle Position”, “Idle Switch”, “Brake Switch 1”
and “Brake Switch 2” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.

Diagnostic Trouble Code (DTC) P1120 (Symptom Code 1) (Flash Code 21)

Pedal/Throttle Position Sensor Circuit High Input

Flash

Code

Symptom

Code

MIL

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

P1120

Pedal/Throttle Position Sen-
sor Circuit High Input

Throttle position sensor out-
put voltage is more than 4.5V.

ECM increases idle speed up
to 1400rpm.

Pedal/Throttle Position Sen-
sor Voltage Supply Circuit
High Input

Throttle position sensor power
supply voltage is more than
5.2V.

Pedal/Throttle Position Sen-
sor Voltage Supply Circuit
Low Input

Throttle position sensor power
supply voltage is below 4.6V.

Pedal/Throttle Position Sen-
sor Brake Switch Error

1. Engine speed is more than

1700rpm.

2. Vehicle speed is more than

1.5km/h.

3. When brake pedal is

depressed during accelera-
tor pedal is depressing.

Pedal/Throttle Position Sen-
sor Idle Position Switch Error

1. When idle switch is turned

off, throttle position sensor
was below 0.35%.

or
2. When idle switch is tuned

on, throttle position sensor
was more than 7.8%.

Step

Action

Value(s)

Yes

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

—

Go to Step 2

Go to On Board

Diagnostic

(OBD) System

Check

6E–230

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

1. Connect the Tech 2.

2. Review and record the failure information.

3. Select “F0: Read DTC Infor As Stored By ECU” in

“F0: Diagnostic Trouble Codes”.

Is the DTC P1120 (Symptom Code 1) stored as
“Present Failure”?

—

Go to Step 3

Refer to

Diagnostic Aids

and Go to Step

1. Using the Tech 2, ignition “On” and engine “Off”.

2. Select “F1: Clear DTC Information” in “F0:

Diagnostic Trouble Codes” with the Tech 2 and
clear the DTC information.

3. Operate the vehicle and monitor the “F0: Read

DTC Infor As Stored By ECU” in the “F0:
Diagnostic Trouble Codes”.

Was the DTC P1120 (Symptom Code 1) stored in this
ignition cycle?

—

Go to Step 4

Refer to

Diagnostic Aids

and Go to Step

Check for poor/faulty connection at the TPS or ECM
connector. If a poor/faulty connection is found, repair
as necessary.
Was the problem found?

—

Verify repair

Go to Step 5

Visually check the TPS.
Was the problem found?

—

Go to Step 12

Go to Step 6

Step

Action

Value(s)

Yes

2 3

C-56

E-22

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

6E–231

Using the DVM and check the TPS.

1. Ignition “Off”, engine “Off”.

2. Disconnect TPS connector.

3. Measure the resistance of TPS.

Does the tester indicate standard resistance as shown
in the following table?

Standard

resistance

Go to Step 7

Go to Step 12

Using the DVM and check the TPS power supply
circuit.

1. Ignition “On”, engine “Off”.

2. Disconnect the TPS connector.

3. Check the circuit for short to voltage circuit.

Was the DVM indicated specified value?

Approximately

5.0V

Go to Step 9

Go to Step 8

Repair the short to voltage circuit between the ECM
and TPS.
Was the problem solved?

—

Verify repair

Go to Step 14

Step

Action

Value(s)

Yes

Measurement

Terminal

Resistance (

Ω)

1 - 2

Approximately 0.5k

Ω at idle position

Approximately 4.0k

Ω at WOT

2 - 3

Approximately 4.3k

Ω at idle position

Approximately 0.8k

Ω at WOT

1 - 3

Approximately 4.6k

Ω at idle position & WOT

TPS

E-22

C-56

E-22

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