Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 844

6E–105

3.2L ENGINE DRIVEABILITY AND EMISSIONS

and wiring harnesses related to the sensor.  A change
in the display will indicate the location of the fault.

If DTC P0121 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

DTC P0121 –TP System Performance

 

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 not running.
2. Observe the BARO reading on the Tech 2.

Is the BARO reading less than the specified value?

65 kpa

Go to 

Step 3

Go to 

Step 6

3

1. Disconnected the BARO sensor.
2. Connect a test light between the 5 volt reference “A”

circuit and the BARO signal circuit at the BARO
sensor harness connector.

3. Observe the BARO reading on the Tech 2.

Is the BARO reading less than the specified value?

65 kpa

Go to 

Step 5

Go to 

Step 4

4

1. Check the BARO signal circuit between the ECM

and the BARO sensor for an open, short to ground,
or short to the BARO ground circuit.

2. If the BARO signal circuit is open or shorted, repair it

as necessary.

Was the BARO signal circuit open or shorted?

—

Verify repair

Go to 

Step 12

5

Replace the BARO sensor.

Is the action complete?

—

Verify repair

—

6

Observe the TP angle reading on the Tech 2 while
slowly opening the throttle.

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

Closed

throttle = 0%

Wide open

throttle =

100%

Refer to

Diagnostic

Aids

Go to 

Step 7

7

1. Disconnect the TP sensor.
2. Observe the TP sensor reading on the Tech 2.

Is the TP sensor reading near the specified value?

0 V

Go to 

Step 8

Go to 

Step 9

8

1. Connect a test light between the 5 volt reference “A”

circuit and the TP sensor signal circuit at the TP
sensor harness connector.

2. Observe the TP sensor reading on the Tech 2.

Is the TP sensor reading at the specified value?

5 V

Go to 

Step 11

Go to 

Step 10

9

Check the following items:

1. TP signal circuit for a short to voltage.
2. TP sensor ground circuit for high resistance

between the ECM and the TP sensor.

3. TP 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 12

6E–106 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0121 –TP System Performance

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

Check the following items:

1. TP signal circuit or 5 volt reference “A” circuit for a

poor connection.

2. TP signal circuit or 5 volt reference “A” circuit for

high resistance between the ECM and the TP
sensor.

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

necessary.

Was a problem found?

—

Verify repair

Go to 

Step 12

11

Replace the TP sensor.

Is the action complete?

—

Verify repair

—

12

Replace the ECM.

Is the action complete?

—

Verify repair

—

6E–107

3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0122 (Flash DTC=21) TP Sensor Circuit Low

Voltage

060RW072

Circuit Description

The throttle position (TP) sensor circuit provides a voltage
signal that changes relative to throttle blade angle.  The
signal voltage will vary from below 0.6 volts at closed
throttle to about 4.5 volts at wide open throttle (WOT).
The TP signal is used by the Engine Control Module ECM
for fuel control and many of the ECM-controlled outputs.

Conditions for Setting the DTC

D

Ignition SW is ON.

D

The Tp sensor voltage reading is below 100m volts.

D

Above conditions present for at least 1 second.

Action Taken When the DTC Sets

D

The ECM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

D

The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

D

The ECM will use a default throttle position based on
mass air flow and RPM.

Conditions for Clearing the MIL/DTC

D

The ECM 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 P0122 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

D

DTC P0122 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the ECM battery
feed.

Diagnostic Aids

Check for the following conditions:

D

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.

D

Damaged harness – Inspect the wiring harness for
damage.  If the harness appears to be OK, observe the
throttle position display on the Tech 2 while moving
connectors and wiring harnesses related to the TP
sensor.  A change in the display will indicate the
location of the fault.

If DTC P0122 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

6E–108 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0122 –TP Sensor Circuit  Low Voltage

 

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. With the throttle closed, observe the “TP Sensor”

display on the Tech 2.

Is the “TP Sensor” below the specified value?

0.22 V

Go to 

Step 4

Go to 

Step 3

3

1. Ignition “ON,” engine “OFF.”
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records

conditions as noted.

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

DTC P0122.

Does the Tech 2 indicate DTC P0122 failed?

—

Go to 

Step 4

Refer to

Diagnostic

Aids

4

1. Ignition “OFF.”
2. Disconnect the TP sensor electrical connector.
3. Jumper the 5 volt reference “A” circuit and the TP

signal together at the TP sensor harness connector.

4. Ignition “ON.”
Observe the “TP Sensor” display on the Tech 2.

Is the “TP Sensor” at the specified value?

5 V

Go to 

Step 10

Go to 

Step 5

5

1. Disconnect jumper.
2. Connect a test light between B+ and the TP sensor

signal circuit at the TP sensor harness connector.

Observe the “TP Sensor” display on the Tech 2.

Is the “TP Sensor” at the specified value?

5 V

Go to 

Step 6

Go to 

Step 8

6

1. Ignition “OFF.”
2. Disconnect the ECM and check the 5 volt reference

“A” circuit for an open or short to ground.

3. If the 5 volt reference “A” circuit is open or shorted to

ground, repair it as necessary.

Was the 5 volt reference “A” circuit open or shorted to
ground?

—

Verify repair

Go to 

Step 7

7

Check the 5 volt reference “A” circuit for a poor
connection at the ECM and replace the terminal if
necessary.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 12

8

1. Ignition “OFF.”
2. Disconnect the ECM, and check the TP signal

circuit for an open, short to ground, or short to the
sensor ground circuit.

3. If the TP sensor signal circuit is open or shorted to

ground, repair it as necessary.

Was the TP signal circuit open or shorted to ground?

—

Verify repair

Go to 

Step 9

9

Check the TP sensor signal circuit for a poor
connection at the ECM and replace the terminal if
necessary.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 12