Infiniti Q45 (FY33). Manual — part 154
SEF594K
Engine Coolant Temperature Sensor (ECTS)
COMPONENT DESCRIPTION
The engine coolant temperature sensor is located near the No. 2
injector. The sensor is used to detect the engine coolant tempera-
ture. The sensor modifies a voltage signal from the ECM. The
modified signal returns to the ECM as the engine coolant tempera-
ture input. The sensor uses a thermistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.
SEF012P
<Reference data>
Engine coolant tempera-
ture
°C (°F)
Voltage*
V
Resistance
k
Ω
−10 (14)
4.4
7.0 - 11.4
20 (68)
3.5
2.1 - 2.9
50 (122)
2.2
0.68 - 1.00
90 (194)
1.0
0.236 - 0.260
*: These data are reference values and are measured between ECM terminal
q
67
(Engine coolant temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring voltage.
Doing so may result in damage to the ECM’s transistor. Use a
ground other than ECM terminals such as the body ground.
ON BOARD DIAGNOSIS LOGIC
Diagnostic
Trouble Code
No.
Malfunction is detected when ...
Check Items
(Possible Cause)
P0115
0103
I
An excessively high or low voltage from the sensor is
sent to ECM.*
I
Harness or connectors
(The sensor circuit is open or shorted.)
I
Engine coolant temperature sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.
Engine operating condition in fail-safe mode
Condition
Engine coolant temperature decided
(CONSULT-II DISPLAY)
Engine coolant temperature will be determined
by ECM based on the time after turning igni-
tion switch “ON” or “START”.
CONSULT-II displays the engine coolant tem-
perature decided by ECM.
Just as ignition switch is turned ON or Start
40°C (104°F)
More than 4 minutes after ignition Start
80°C (176°F)
Except as shown above
40 - 80°C (104 - 176°F)
(Depends on the time)
GI
MA
EM
LC
FE
AT
PD
FA
RA
BR
ST
RS
BT
HA
EL
IDX
TROUBLE DIAGNOSIS FOR DTC P0115
EC-145
SEF399X
DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE
NOTE:
If “DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCE-
DURE” has been previously conducted, always turn ignition
switch “OFF” and wait at least 5 seconds before conducting
the next test.
1) Turn ignition switch “ON”.
2) Select “DATA MONITOR” mode with CONSULT-II.
3) Wait at least 5 seconds.
4) If 1st trip DTC is detected, go to “DIAGNOSTIC
PROCEDURE”, EC-148.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ OR ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Follow the procedure “With CONSULT-II” above.
TROUBLE DIAGNOSIS FOR DTC P0115
Engine Coolant Temperature Sensor (ECTS)
(Cont’d)
EC-146
TEC043M
GI
MA
EM
LC
FE
AT
PD
FA
RA
BR
ST
RS
BT
HA
EL
IDX
TROUBLE DIAGNOSIS FOR DTC P0115
Engine Coolant Temperature Sensor (ECTS)
(Cont’d)
EC-147
SEF052T
SEF541P
SEF542P
DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK POWER SUPPLY.
1. Turn ignition switch “OFF”.
2. Disconnect engine coolant temperature
sensor harness connector.
3. Turn ignition switch “ON”.
4. Check voltage between terminal
q
2
and
ground with CONSULT-II or tester.
Voltage:
Approximately 5V
OK
E
NG
Check the following.
I
Harness connectors
F26
,
F106
I
Harness for open or
short between ECM and
engine coolant tempera-
ture sensor
If NG, repair harness or
connectors.
CHECK GROUND CIRCUIT.
1. Turn ignition switch “OFF”.
2. Check harness continuity between ter-
minal
q
1
and engine ground.
Continuity should exist.
If OK, check harness for short to power.
OK
E
NG
Check the following.
I
Harness connectors
F26
,
F106
I
Harness connectors
F63
,
M49
I
Harness connectors
M4
,
B3
I
Joint connector-16
I
Harness for open or
short between ECM and
engine coolant tempera-
ture sensor
I
Harness for open or
short between TCM
(Transmission Control
Module) and engine
coolant temperature sen-
sor
I
Harness for open or
short between engine
coolant temperature sen-
sor and throttle actuator
control (TAC) module
If NG, repair open circuit or
short to ground or short to
power in harness or con-
nectors.
CHECK COMPONENT
(Engine coolant temperature sensor).
Refer to “COMPONENT INSPECTION” on
next page.
OK
E
NG
Replace engine coolant
temperature sensor.
Perform “TROUBLE DIAGNOSIS FOR
INTERMITTENT INCIDENT”, EC-117.
INSPECTION END
TROUBLE DIAGNOSIS FOR DTC P0115
Engine Coolant Temperature Sensor (ECTS)
(Cont’d)
H
H
H
H
H
EC-148
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