Isuzu Rodeo UE. Manual - part 404

6E2–371

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1115 ECT Sensor Circuit Intermittent High

Voltage

D06RW058

Circuit Description

The engine coolant temperature (ECT) sensor is a
thermistor mounted in the engine coolant stream. The
powertrain control module (PCM) applies a voltage
(about 5.0 volts) through a pull-up resistor to the ECT
signal circuit. When the engine coolant is cold, the sensor
(thermistor) resistance is high, therefore the PCM will
measure a high signal voltage. As the engine coolant
warms, the sensor resistance becomes less, and the
ECT signal voltage measured at the PCM drops. With a
fully warmed up engine, the ECT signal voltage should
measure about 1.5 to 2.0 volts. If the PCM detects an
ECT signal that is intermittently above the range of the
ECT sensor, DTC P1115 will set.

Conditions for Setting the DTC

Engine running time longer than 90 seconds.

The ECT sensor signal is intermittently greater than
–39

C (–38

F) (about 5 volts) for a total of 10 seconds

over a 100-second period.

Action Taken When the DTC Sets

The PCM will not illuminate the malfunction indicator
lamp (MIL).

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

Conditions for Clearing the MIL/DTC

A history DTC P1115 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1115 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

Check for the following conditions:

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.

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

Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.

6E2–372

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Engine Coolant Temperature Sensor

OHMS

Temperature vs. Resistance Values (approximate)

100

212

177

176

332

140

667

113

1188

1802

2796

4450

7280

–5

12300

–15

21450

–30

–22

52700

–40

100700

6E2–373

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P1115 –ECT Sensor Circuit Intermittent High Voltage

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

Is DTC P0118 also set?

—

Go to

DTC

P0118 chart

first

Go to

Step 3

Is DTC P1106, P1111, and/or P1121 also set?

—

Go to

Step 8

Go to

Step 4

1. Check for a poor sensor ground circuit terminal

connection at the ECT sensor.

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

Was a problem found?

—

Verify repair

Go to

Step 5

1. Check for a poor ECT signal circuit terminal

connection at the ECT sensor.

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

Was a problem found?

—

Verify repair

Go to

Step 6

1. Check the ECT signal circuit between the ECT

sensor connector and the PCM for an intermittent
open.

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

Was a problem found?

—

Verify repair

Go to

Step 7

1. Check the ECT signal circuit between the ECT

sensor connector and the PCM for an intermittent
short to voltage.

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

Was a problem found?

—

Verify repair

Go to

Step 8

1. Check for a poor sensor ground circuit terminal

connection at the PCM.

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

Was a problem found?

—

Verify repair

Go to

Step 9

1. Check for an intermittent open or a faulty splice in

the sensor ground circuit.

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

Was a problem found?

—

Verify repair

Refer to

Diagnostic

Aids

6E2–374

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1121 TP Sensor Circuit Intermittent High

Voltage

D06RW059

Circuit Description

The throttle position (TP) sensor circuit provides voltage
signal that changes relative to the throttle blade angle.
The signal voltage will vary from about 0.6 volts at closed
throttle to about 4.5 volts at wide open throttle (WOT).
The TP signal is one of the most important inputs used by
the powertrain control module (PCM) for fuel control and
for most of the PCM controlled outputs. If the PCM
detects a TP signal that is intermittently above the range
of the TP sensor, DTC P1121 will be set.

Conditions for Setting the DTC

The ignition is “ON.”

TP sensor indicates a throttle position voltage
intermittently greater than 4.9 volts for a total of 0.15
seconds over a 1.5-second period.

Action Taken When the DTC Sets

The PCM will not illuminate the malfunction indicator
lamp (MIL).

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

Conditions for Clearing the MIL/DTC

A history DTC P1121 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1121 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

Check for the following conditions:

Poor connection at PCM – Inspect the harness
connectors for backed-out terminals, improper mating,
broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.

The TP Sensor shares a 5 Volt reference with the EGR
Valve.

If these codes are also set, it could indicate a
problem with the 5 Volt reference circuit or
components itself.

The TP Sensor share a ground with the EGR Valve and
the IAT Sensor.

Check the ground if these other DTCs are also
set.

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 P1121 cannot be duplicated, reviewing the Failure
Records vehicle mileage since the diagnostic test last
failed may help to determine how often the condition that

Content .. 402 403 404 405 ..