TOYOTA CAMRY 1999 Service Repair Manual

FI6448
Intake Air Temp. Sensor
(Inside the Mass Air Flow Meter)ECM
5 V
THA
E2
E1 1
2R
L±Y
BR
E10E1022
18
± DIAGNOSTICSENGINE (1MZ±FE)
DI±229
464 Author: Date:
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

If DTCs P0110 (Intake Air Temp. Circuit Malfunction), P0115 (Engine Coolant Temp. Circuit Malfunc-
tion), P0120 (Throttle/Pedal Position Sensor/Switch ºAº Circuit Malfunction) and P1410 (EGR Valve
Position Sensor Circuit Malfunction) are output simultaneously, E2 (Sensor Ground) may be open.

Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected, when troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel
ratio lean or rich, etc. at the time of the malfunction.

A00210
ON
Intake Air
Temp. Sensor
ECM
5 V
E2THA
1
2
E10 E10
22
18
DI±230
± DIAGNOSTICSENGINE (1MZ±FE)
465 Author: Date:
1 Connect OBD II scan tool or TOYOTA hand±held tester, and read value of
intake air temp.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the OBD II scan tool or TOYOTA hand±held tester main switch
ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA hand±held tester.
OK:
Same as actual intake air temp.
HINT:

If there is open circuit, OBD II scan tool or TOYOTA hand±held tester indicates ±40°C (-40°F).

If there is short circuit, OBD II scan tool or TOYOTA hand±held tester indicates 140°C (284°F) or more.
NG ±40°C (±40°F) ... Go to step 2.
140°C (284°F) or more ... Go to step 4.
OK
Check for intermittent problems
(See page DI±197).
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the mass air flow meter connector.
(b) Connect sensor wire harness terminals together.
(c) Turn the ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temp. value: 1405C (2845F) or more
OK Confirm good connection at sensor.
If OK, replace mass air flow meter.
NG

A02019
Intake Air Temp. Sensor ON22
18E10
E10THA5 V
E2
E2 THA
ECM
A00212
ON
Intake Air
Temp. Sensor
ECM
5 V
E2
22
THA
E10 E1018
± DIAGNOSTICSENGINE (1MZ±FE)
DI±231
466 Author: Date:
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See page SF±73).
(b) Connect between terminals THA and E2 of ECM connec-
tor.
HINT:
Mass air flow meter connector is disconnected.
Before checking, do a visual and contact pressure check for the
ECM connector (See page IN±31).
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temp. value: 1405C (2845F) or more
OK Open in harness between terminal E2 or THA,
repair or replace harness.
NG
Confirm good connection at ECM.
If OK, check and replace ECM.
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the mass air flow meter connector.
(b) Turn the ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temp. value: ±405C (±405F)
OK Replace mass air flow meter.
NG

A02043
ON
Intake Air Temp. Sensor
E10
THA
E25 V
ECM
DI±232
± DIAGNOSTICSENGINE (1MZ±FE)
467 Author: Date:
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See page SF±73).
(b) Disconnect the E10 connector of ECM.
HINT:
Mass air flow meter connector is disconnected.
(c) Turn the ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temp. value: ± 405C (± 405F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN±31).

FI6448
Engine Coolant Temp. SensorECM
5V
THW
E2
E1 2
1G±B
BR
E10
14
18
E10
± DIAGNOSTICSENGINE (1MZ±FE)
DI±233
468 Author: Date:
DTC P0115 Engine Coolant Temp. Circuit Malfunction

CIRCUIT DESCRIPTION
A thermistor built into the engine coolant temp. sensor changes the resistance value according to the engine
coolant temp.
The structure of the sensor and connection to the ECM is the same as in the intake air temp. circuit malfunc-
tion shown on page DI±228.
If the ECM detects the DTC P0115, it operates fail±safe function in which the engine coolant temperature
is assumed to be 80°C (176°F).
DTC No.Detection ItemTrouble Area
P0115Open or short in engine coolant temp. sensor circuit

Open or short in engine coolant temp. sensor circuit

Engine coolant temp. sensor

ECM
HINT:
After confirming DTC P0115, use the OBD II scan tool or TOYOTA hand±held tester to confirm the engine
coolant temp. from CURRENT DATA.
Temperature DisplayedMalfunction
±40°C (±40°F)Open circuit
140°C (284°F) or moreShort circuit
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

If DTCs P0110 (Intake Air Temp. Circuit Malfunction), P0115 (Engine Coolant Temp. Circuit Malfunc-
tion), P0120 (Throttle/Pedal/Position Sensor/Switch ºAº Circuit Malfunction) and P1410 (EGR Valve
Position Sensor Circuit Malfunction) are output simultaneously, E2 (Sensor Ground) may be open.

Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected, when troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel
ratio lean or rich, etc. at the time of the malfunction.
DI07I±06

A00214
ON
Engine Coolant
Temp. Sensor
ECM
5 V
E2
2
1
THWE10
E101814
DI±234
± DIAGNOSTICSENGINE (1MZ±FE)
469 Author: Date:
1 Connect OBD II scan tool or TOYOTA hand±held tester, and read value of engine
coolant temperature.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the OBD II scan tool or TOYOTA hand±held tester main switch
ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA hand±held tester.
OK:
Same as actual engine coolant temperature.
HINT:

If there is open circuit, OBD II scan tool or TOYOTA hand±held tester indicates ±40°C (±40°F).

If there is open circuit, OBD II scan tool or TOYOTA hand-held tester indicates 140°C (284°F) or more.
NG ±40°C (±40°F) ... Go to step 2.
140°C (284°F) or more ... Go to step 4.
OK
Check for intermittent problems
(See page DI±197).
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the engine coolant temp. sensor connector.
(b) Connect the sensor wire harness terminals together.
(c) Turn the ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temperature value: 1405C (2845F) or more
OK Confirm good connection at sensor.
If OK, replace engine coolant temp. sensor.
NG

A02020
ON
Engine Coolant Temp. Sensor
ECM
THW E2
E10
E1014
185 V
THW
E2
1 2
A00216
ON
Engine Coolant
Temp. Sensor
ECM
5 V
E2 THWE1018 14
E10
± DIAGNOSTICSENGINE (1MZ±FE)
DI±235
470 Author: Date:
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See page SF±73).
(b) Connect between terminals THW and E2 of the ECM con-
nector.
HINT:
Engine coolant temp. sensor connector is disconnected. Be-
fore checking, do a visual and contact pressure check for the
ECM connector (See page IN±31).
(c) Turn the ignition switch ON.
CHECK:
Read temperature. value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temperature value: 1405C (2845F) or more
OK Open in harness between terminal E2 or THW,
repair or replace harness.
NG
Confirm good connection at ECM.
If OK, check and replace ECM.
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the engine coolant temp. sensor connector.
(b) Turn the ignition switch ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temperature value: ±405C (±405F)
OK Replace engine coolant temp. sensor.
NG

A02043
ON
ECM
Engine Coolant Temp. Sensor
THW
E2
E105 V
DI±236
± DIAGNOSTICSENGINE (1MZ±FE)
471 Author: Date:
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See page SF±73).
(b) Disconnect the E10 connector of the ECM.
HINT:
Engine coolant temp. sensor connector is disconnected.
(c) Turn the ignition switch ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA
hand±held tester.
OK:
Temperature value: ±405C (±405F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN±31).

± DIAGNOSTICSENGINE (1MZ±FE)
DI±237
472 Author: Date:
DTC P0116 Engine Coolant Temp. Circuit Range/
Performance Problem
CIRCUIT DESCRIPTION
Refer to DTC P0115 (Engine Coolant Temp. Circuit Malfunction) on page DI±233.
DTC No.DTC Detecting ConditionTrouble Area
If THW ±7°C (19.4°F), 20 min. or more after starting
engine, engine coolant temp. sensor value is 20°C (68°F) or
less
(2 trip detection logic)
If THW
±7°C (19.4°F) and 10°C (50°F), 5 min. or more
after starting engine,
engine coolant temp. sensor value is 20°C (68°F) or less
(2 trip detection logic)
Engine coolant temp sensorP0116If THW
10°C (50 °F), 2 min. or more after starting engine,
engine coolant temp. sensor value is 30°C (86°F)
(2 trip detection logic)
Engine coolant temp. sensor

Cooling system
When THW
35°C (95°F) or more and less than 60°C
(140°F), THA
± 6.7°C (19.9°F) or more, when starting
engine , condition (a) and (b) continues:
(a) Vehicle speed is changing (Not stable)
(b) When starting engine, THW< 3°C (37.4°F)
(2 trip detection logic)
INSPECTION PROCEDURE
HINT:

If DTCs P0115 (Engine Coolant Temp. Circuit Malfunction) and P0116 (Engine Coolant Temp. Circuit
Range/Performance) are output simultaneously, engine coolant temp. sensor circuit may be open.
Perform troubleshooting of DTC P0115 first.

Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected, when troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel
ratio lean or rich, etc. at the time of the malfunction.
1 Are there any other codes (besides DTC P0116) being output?
YES Go to relevant DTC chart.
NO
DI07J±06

DI±238
± DIAGNOSTICSENGINE (1MZ±FE)
473 Author: Date:
2 Check thermostat (See page CO±9).
NG Replace thermostat.
OK
Replace engine coolant temp. sensor.