Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 1313

6E1–328

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) P1115 ENGINE COOLANT 

TEMPERATURE (ECT) SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE 

060R100028

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, Diagnostic Trouble Code P1115 will set.
Diagnostic Trouble Code P1115 is a type D code.

Conditions for Setting the DTC

D

Engine run time longer than 180 seconds.

D

The ECT sensor signal is intermittently greater than
–39

°

C (–38

°

F) (4.94 volts) for a total of 10 seconds

over a 100–second period.

The conditions are met for 20 test failures within 200 test
samples.

Action Taken When the DTC Sets

D

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

D

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

Conditions for Clearing the DTC

D

A history Diagnostic Trouble Code P1115 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.

D

Diagnostic Trouble Code P1115 can be cleared by
using the Scan Tool’s ”Clear Info” function.

Diagnostic Aids

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; shorts to ground, shorts to battery positive,
and open circuits. 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 Diagnostic Trouble Code to
be set occurs. This may assist in diagnosing the
condition.

6E1–329

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

Engine Coolant Temperature Sensor

°

C

°

F

W

Temperature vs. Resistance Values (approximate)

100

212

177

80

176

332

60

140

667

45

113

1188

35

95

1802

25

77

2796

15

59

4450

5

41

7280

–5

23

12300

–15

5

21450

–30

–22

52700

–40

–40

100700

6E1–330

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DTC P1115 ECT Sensor Circuit Intermittent High 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

Is DTC P0118 also set?

—

Go to DTC

P0118 first 

Go to Step 3 

3

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 4 

4

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 5 

5

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 6 

6

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 7 

7

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 8 

8

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 

6E1–331

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSTIC TROUBLE CODE (DTC) P1121 THROTTLE POSITION (TP) 

SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

060R100029

Circuit Description

The throttle position (TP) sensor circuit provides a voltage
signal that changes relative to the throttle blade angle.
The signal voltage will vary from less than 1 volt at closed
throttle to more than 4 volts at wide open throttle (WOT).
The TP signal is 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,
Diagnostic Trouble Code P1121 will be set.  DTC P1121 is
a type D code.

Conditions for Setting the DTC

D

The ignition is ON.

D

TP sensor indicates a throttle position voltage
intermittently greater than 4.88 volts. The above
conditions are met for 20 test failures within 200 test
samples.

Action Taken When the DTC Sets

D

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

D

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

Conditions for Clearing the DTC

D

A history Diagnostic Trouble Code P1121 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.

D

Diagnostic Trouble Code P1121 can be cleared by
using the Scan Tool’s ”Clear Info” function or by
disconnecting the PCM battery feed.

Diagnostic Aids

Check for the following conditions:

D

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.

D

The TP sensor shares a 5 Volt reference with the MAP
sensor and EGR position sensor.
If these codes are also set, it could indicate a
problem with the 5 Volt reference circuit or
components itself.

D

The TP sensor share a ground with the ECT, the CKP,
the CMP and the automatic transmission position
sensor and the Fuel Pressure sensor.

D

Damaged harness – Inspect the wiring harness for
damage; shorts to ground, shorts to battery positive,
and open circuits. 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.