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DTC 24 Intake Air Temp. Sensor Circuit Malfunction

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rahul_nissan

The document provides information about diagnosing a fault with the intake air temperature sensor circuit on a Toyota 1HZ, 1HD-T, 1HD-FTE diesel engine. It describes the circuit, lists the DTC related to an intake air temperature sensor malfunction, and provides step-by-step inspection procedures to check for open circuits, short circuits, and faults with the sensor or engine control unit wiring harness. The procedures include using a hand-held tester to read intake air temperatures and measure voltages, and inspecting individual circuit components.

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DTC 24 Intake Air Temp. Sensor Circuit Malfunction

Uploaded by

rahul_nissan
553 views6 pages
The document provides information about diagnosing a fault with the intake air temperature sensor circuit on a Toyota 1HZ, 1HD-T, 1HD-FTE diesel engine. It describes the circuit, lists the DTC related to an intake air temperature sensor malfunction, and provides step-by-step inspection procedures to check for open circuits, short circuits, and faults with the sensor or engine control unit wiring harness. The procedures include using a hand-held tester to read intake air temperatures and measure voltages, and inspecting individual circuit components.

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service details

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The document provides information about diagnosing a fault with the intake air temperature sensor circuit on a Toyota 1HZ, 1HD-T, 1HD-FTE diesel engine. It describes the circuit, lists the DTC related to an intake air temperature sensor malfunction, and provides step-by-step inspection procedures to check for open circuits, short circuits, and faults with the sensor or engine control unit wiring harness. The procedures include using a hand-held tester to read intake air temperatures and measure voltages, and inspecting individual circuit components.

Copyright:

© All Rights Reserved
Download as PDF, TXT or read online from Scribd
Download as pdf or txt
553 views6 pages

DTC 24 Intake Air Temp. Sensor Circuit Malfunction

Uploaded by

rahul_nissan
The document provides information about diagnosing a fault with the intake air temperature sensor circuit on a Toyota 1HZ, 1HD-T, 1HD-FTE diesel engine. It describes the circuit, lists the DTC related to an intake air temperature sensor malfunction, and provides step-by-step inspection procedures to check for open circuits, short circuits, and faults with the sensor or engine control unit wiring harness. The procedures include using a hand-held tester to read intake air temperatures and measure voltages, and inspecting individual circuit components.

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© All Rights Reserved
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DI46

DIAGNOSTICS

ENGINE
DI3S801

DTC

24

Intake Air Temp. Sensor Circuit Malfunction

CIRCUIT DESCRIPTION
The intake air temp. sensor is built into the intake manifold and
senses the intake air temperature. A thermistor built in the sensor changes the resistance value according to the intake air
temperature. The lower the intake air temperature, the greater
the thermistor, the lower the thermistor resistance value (See
Fig.1).The intake air temperature sensor is connected to the engine ECU. The 5 V power source voltage in the engine ECU is
applied to the intake air temperature sensor from the terminal
THA via a resistor R. That is the resistor R and the intake air
temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes.
Based on this signal, the engine ECU increases the fuel injection volume to improve drivability during cold engine operation.

(Fig.1)
30
20
10

Acceptable

Resistance kW

5
3
2
1
0.5
0.3
0.2
0.1
20 0
(4) 32

20
68

40 60
104 140

80 100
176 212

Temp. C (F)
FI4741

DTC No.

DTC Detecting Condition

24

Open or short in intake air temp. sensor circuit for 0.5 sec. or
more

Trouble Area
S Open or short in intake air temp. sensor circuit
S Intake air temp. sensor
S Engine ECU

HINT:
After confirming DTC 24 use the handheld tester to confirm the water temperature from CURRENT DATA.
Temperature displayed

Malfunction

40C (40F)

Open circuit

140C (284F) or more

Short circuit

1HZ, 1HDT, 1HDFTE ENGINE (RM617E)

DI47
DIAGNOSTICS

ENGINE

WIRING DIAGRAM

Engine ECU
Intake Air Temp. Sensor

5V
3

WG

BRW (A/T)
BRW
(M/T)

E16
9
E16

THA

E2
E1

BRW
(M/T)

A
J8 J/C

B05259

INSPECTION PROCEDURE
HINT:
If DTC22 (Water Temp. Sensor Circuit Malfunction), 24 (Intake Air Temp. Sensor Circuit Malfunction), 35
(Turbo Pressure Sensor Circuit Malfunction) and 39 (Fuel Temp. Sensor Circuit Malfunction) are output
simultaneously, E2 (sensor ground) may be open.

1HZ, 1HDT, 1HDFTE ENGINE (RM617E)

DI48
DIAGNOSTICS

ENGINE

When using handheld tester


1

Connect the handheld tester, and read value of water temperature.

PREPARATION:
(a) Connect the handheld tester to the DLC3.
(b) Turn the ignition switch ON and push the handheld tester main switch ON.
CHECK:
Read temperature value on the handheld tester.
OK:
Same as actual intake air temperature.
HINT:
S
If there is open circuit, handheld tester indicates 40C (40F).
S
If there is short circuit, handheld tester indicates 140C (284F) or more.
NG

40C (40F) ... Go to step 2.


140C (284F) or more ... Go to step 4.

OK

Check for intermittent problems (See page DI4).

Check for open in harness or engine ECU.


ON

Intake Air
Temp. Sensor

Engine ECU
2

3
E16

5V
THA

9 E2
E16
1
BE6653
FI7055

E1

PREPARATION:
(a) Disconnect the intake air temp. sensor connector.
(b) Connect sensor wire harness terminals together.
(c) Turn the ignition switch ON.
CHECK:
Read temperature value on the handheld tester.
OK:
Temperature value: 140C (284F) or more

A00214

OK

NG

1HZ, 1HDT, 1HDFTE ENGINE (RM617E)

Confirm good connection at sensor.


If OK, replace intake air temp. sensor.

DI49
DIAGNOSTICS

ENGINE

Check for open in harness or engine ECU.


ON

Intake Air
Temp. Sensor

Engine ECU
2

5V

THA

E2

E16

E16

BE6653
FI7057
A04953

THA

E1

E2

PREPARATION:
(a) Remove the glove compartment door.
(b) Connect between terminals THA and E2 of engine ECU
connector.
HINT:
Intake air temp. sensor connector is disconnected.
Before checking, do a visual and contact pressure check for the
engine ECU connector (See page IN19).
(c) Turn the ignition switch ON.
CHECK:
Read temperature value on the handheld tester.
OK:
Temperature value: 140C (284F) or more

A05045

OK

Open in harness between terminal E2 or THA,


repair or replace harness.

NG

Confirm good connection at engine ECU. If OK, replace engine ECU.

Check for short in harness and engine ECU.


ON

Intake Air
Temp. Sensor

Engine ECU
5V
3
E16

9
E16

THA
E2

BE6653
FI7054

NG

1HZ, 1HDT, 1HDFTE ENGINE (RM617E)

E1

A00216

PREPARATION:
(a) Disconnect the intake air temp. sensor connector.
(b) Turn the ignition switch ON.
CHECK:
Read temperature value on the handheld tester.
OK:
Temperature value: 40C (40F)
OK

Replace intake air temp. sensor.

DI50
DIAGNOSTICS

ENGINE

Check for short in harness or engine ECU.


ON
Intake Air
Temp. Sensor
2

Engine ECU
5V
THA
E2

BE6653
F17056
A05037

E1

E16 Connector

A05289

PREPARATION:
(a) Remove the glove compartment door.
(b) Disconnect the E16 connector of engine ECU.
HINT:
Intake air temp. sensor connector is disconnected.
(c) Turn the ignition switch ON.
CHECK:
Read temperature value on the handheld tester.
OK:
Temperature value: 40C (40F)

OK

NG

Check and replace engine ECU (See page IN19).

1HZ, 1HDT, 1HDFTE ENGINE (RM617E)

Repair or replace harness or connector.

DI51
DIAGNOSTICS

ENGINE

When not using handheld tester


1

Check voltage between terminals THA and E2 engine ECU connector.


ON

PREPARATION:
(a) Remove the glove compartment door.
(b) Turn the ignition switch ON.
CHECK:
Measure voltage between terminals THA and E2 of engine
ECU connector.
OK:

E2

THA

(+)

()
A04954

Intake air temp.


C (F)

Voltage

20 (68)
(Engine is cool)

0.2 3.8 V

80 (176)
(Engine is hot)

0.1 1.5 V

OK

Check for intermittent problems


(See page DI4).

NG

Check intake air temp. sensor (See page ED7).

NG

Replace intake air temp. sensor.

OK

Check for open and short in harness and connector between engine ECU and
intake air temp. sensor (See page IN19).

NG

OK

Check and replace engine ECU (See page IN19).

1HZ, 1HDT, 1HDFTE ENGINE (RM617E)

Repair or replace harness or connector.

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