Opel Frontera UBS. Manual - part 1190

 

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Opel Frontera UBS. Manual - part 1190

 

 

6E–126

ENGINE DRIVEABILITY AND EMISSIONS

DTC P0117 – ECT Sensor  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. Observe the “Eng Cool Temp” display on the Tech 2.

Is the “Eng Cool Temp” below the specified value?

139

°

C

(282

°

F)

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 “Specific DTC” info for DTC

P0117.

Does the Tech 2 indicate DTC P0117 failed this
ignition?

Go to 

Step 4

Refer to

Diagnostic

Aids

4

1. Disconnect the ECT sensor electrical connector.
2. Observe the “Eng Cool Temp” display on the Tech 2.

Is the “Eng Cool Temp” at the specified value?

–39

°

C

(–38

°

F)

Go to 

Step 6

Go to 

Step 5

5

1. Ignition “OFF.”
2. Disconnect the PCM and check the ECT signal

circuit for a short to ground or a short to the sensor
ground circuit.

3. If the ECT signal circuit is shorted. repair it as

necessary.

Was the ECT signal circuit shorted to ground?

Verify repair

Go to 

Step 7

6

Replace the ECT sensor.

Is the action complete?

Verify repair

7

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.  Refer to 

UBS 98model year Immobilizer

Workshop Manual.

Is the action complete?

Verify repair

6E–127

ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0118 ECT Sensor Circuit High Voltage

060RY00304

Circuit Description

The engine coolant temperature (ETC) sensor is a
thermistor mounted in on a coolant crossover pipe at the
rear of the engine.  The powertrain control module (PCM)
applies a voltage (about 5 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.

Conditions for Setting the DTC

D

Engine running time is longer than 1.5 minutes.

D

The ECT sensor signal indicates an engine coolant
temperature of –39

°

C (–38

°

F) or less (about 5 volts)

for a total of 50 seconds over a 100-second period.

Action Taken When the DTC Sets

D

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

D

The PCM will substitute the ECT reading with a default
engine coolant temperature value.  The default value
is based on start-up intake air temperature and running
time.

D

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

Conditions for Clearing the MIL/DTC

D

DTC P0118 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:
The ECT shares a ground with the Transmission Fluid
Temperature sensor, the Rough Road sensor, and the
MAP sensor.
Check the ground if these DTCs are also set.

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
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.

If DTC P0118 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
If it is determined that the DTC occurs intermittently,
performing the DTC P1115 Diagnostic Chart may isolate
the cause of the fault.

6E–128

ENGINE DRIVEABILITY AND EMISSIONS

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Verifies that the fault is present.

3. If DTC P0118 can be repeated only by duplicating

the Failure Records conditions, refer to the
“Temperature vs. Resistance Value” table.  The
table may be used to test the ECT sensor at various
temperatures to evaluate the possibility of a
“shifted” sensor that may be shorted above or below
a certain temperature.  If this is the case, replace
the ECT sensor.  If the ECT sensor appears to be
OK, the fault is intermittent; refer to 

Diagnostic Aids.

Engine Coolant Temperature Sensor

°

C

°

F

OHMS

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

DTC P0118 – ECT Sensor Circuit 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

1. Ignition “ON,” engine “OFF.”
2. Observe the “Eng Cool Temp” display on the Tech 2.

Is the “Eng Cool Temp” below the specified value?

–39

°

C

(–38

°

F)

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 P0118.

Does the Tech 2 indicate DTC P0118 failed?

Refer to 

Test

Description

Refer to

Diagnostic

Aids

4

1. Disconnect the ECT sensor electrical connector.
2. Jumper the ECT signal circuit and the sensor

ground circuit together at the ECT sensor harness
connector.

3. Observe the “Eng Cool Temp” display on the Tech 2.

Is the “Eng Cool Temp” at the specified value?

140

°

C

(284

°

F)

Go to 

Step 6

Go to 

Step 5

5

1. Jumper the ECT signal circuit at the ECT sensor

harness connector to chassis ground.

2. Observe the “Eng Cool Temp” display on the Tech 2.

Is the “Eng Cool Temp” at the specified value?

140

°

C

(284

°

F)

Go to 

Step 7

Go to 

Step 8

6

Check for poor connections at the ECT sensor and
replace terminals if necessary.

Did any terminals require replacement?

Verify repair

Go to 

Step 10

6E–129

ENGINE DRIVEABILITY AND EMISSIONS

DTC P0118 – ECT Sensor Circuit High Voltage

  (Cont'd)

Step

No

Yes

Value(s)

Action

7

1. Ignition “OFF.”
2. Disconnect the PCM, and check the ECT sensor

ground circuit for an open.

3. If the ECT sensor ground circuit is open, repair it as

necessary.

Was the ECT sensor ground circuit open?

Verify repair

Go to 

Step 9

8

1. Ignition “OFF.”
2. Disconnect the PCM, and check the ECT signal

circuit for an open.

3. If the ECT sensor signal circuit is open, repair it as

necessary.

Was the ECT signal circuit open?

Verify repair

Go to 

Step 9

9

Check for a poor sensor ground or ECT signal circuit
terminal connection at the PCM and replace
terminal(s) if necessary.

Did any of the terminals need to be replaced?

Verify repair

Go to 

Step 11

10

Replace the ECT sensor.

Is the action complete?

Verify repair

11

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.  Refer to 

UBS 98model year Immobilizer

Workshop Manual.

Is the action complete?

Verify repair

 

 

 

 

 

 

 

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