1999 TOYOTA CAMRY OBD port

DI00M±07
P01242
Manifold Absolute Pressure450
150 1.2
750 3.6 (3.96)
2.4V
100mmHg
20(840)
60kPa
(112)
Output Voltage
DI±22
± DIAGNOSTICSENGINE
CIRCUIT INSPECTION
DTC P0105 Manifold Absolute Pressure/Barometric
Pressure Circuit Malfunction
CIRCUIT DESCRIPTION
By a built±in sensor unit, the manifold absolute pressure sensor
detects the intake manifold pressure as a voltage. The ECM
then determines the basic injection duration and basic injection
advance angle based on this voltage. Since the manifold abso-
lute pressure sensor does not use the atmospheric pressure as
a criterion, but senses the absolute pressure inside the intake
manifold (the pressure in proportion to the present absolute
vacuum 0), it is not influenced by fluctuations in the atmospheric
pressure due to high altitude and other factors. This permits it
to control the air±fuel ratio at the proper lever under all condi-
tions.
DTC No.DTC Detecting ConditionTrouble Area
P0105Open or short in manifold absolute pressure sensor circuit

Open or short in manifold absolute pressure sensor circuit

Manifold absolute pressure sensor

ECM
HINT:
After confirming DTC P0105, use the OBD II scan tool or TOYOTA hand±held tester to confirm the manifold
absolute pressure from the CURRENT DATA.
Manifold Absolute Pressure (kPa)Malfunction
Approx. 0
PIM circuit short
130 or more

VC circuit open or short

PIM circuit open

E2 circuit open

P24296
Throttle Position
Sensor
VC
VTA
E2ECM
A09396
Throttle Position Sensor
ECM
E5
E5 1
3
2Y
LG
BR1
11
9VC
VTA
E25 V
E5
± DIAGNOSTICSENGINE
DI±35
DTC P0120 Throttle/Pedal Position Sensor/Switch ºAº
Circuit Malfunction
CIRCUIT DESCRIPTION
The throttle position sensor is mounted in the throttle body and
detects the throttle valve opening angle. When the throttle valve
is fully closed, a voltage of approximately 0.3 ± 0.8 V is applied
to terminal VTA of the ECM. The voltage applied to the termi-
nals VTA of the ECM increases in proportion to the opening
angle of the throttle valve and becomes approximately 3.2 ± 4.9
V when the throttle valve is fully opened. The ECM judges the
vehicle driving conditions from this signal input from terminal
VTA, and uses it as one of the conditions to decide the air±fuel
ratio correction, power increase correction and fuel±cut control
etc.
DTC No.DTC Detecting ConditionTrouble Area
P0120
Condition (a) or (b) continues with more than 5 sec.
(a) VTA < 0.1 V
(b) VTA > 4.9 V
Open or short in throttle position sensor circuit

Throttle position sensor

ECM
HINT:
After confirming DTC P0120, use the OBD II scan tool or TOYOTA hand±held tester to confirm the throttle
valve opening percentage.
Throttle valve opening position expressed as percentageTblAThrottle valve fully closedThrottle valve fully openTrouble Area
0 %0 %
VC circuit open

VTA circuit open or ground short
Approx. 100 %Approx. 100 %
E2 circuit open
WIRING DIAGRAM
DI00R±07

A00477
Atmosphere
Cover
Exhaust GasPlatinum
Electrode
Solid Electrolyte
(Zirconia Element)
Platinum
Electrode
Heater
Air±Fuel Ratio
(V)
2.6 4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.4
14 15 16 17 19 21 22
Coating (Ceramic)
ECM Monitored
A/F Sensor Voltage
DI±40
± DIAGNOSTICSENGINE
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three±way cata-
lytic converter is used, but for the most efficient use of the three±way catalytic converter, the air±fuel ratio
must be precisely controlled so that it is always close to the stoichiometric air±fuel ratio.
The A/F sensor has the characteristic that provides output voltage
* approximately proportional to the exist-
ing air±fuel ratio. The A/F sensor output voltage
* is used to provide feedback for the ECM to control the air±
fuel ratio.
By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air±fuel ratio
and control the proper injection time immediately. If the A/F sensor is malfunctioning, ECM is unable to per-
form accurate air±fuel ratio control.
The A/F sensor is equipped with a heater which heats the zirconia element. The heater is controlled by the
ECM. When the intake air volume is low (the temp. of the exhaust gas is low), current flows to the heater
to heat the sensor for accurate oxygen concentration detection.
*: The voltage value changes at the inside of the ECM only.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, A/F sensor output* does not
change when conditions (a), (b) and (c) continue for at least
1.5 min.:
*: Output value changes at inside of ECM only
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 ± 100 km/h (25 ± 62 mph)
(c) Throttle valve is not fully closed
Open or short in A/F sensor (bank 1 sensor 1) circuit

A/F sensor (bank 1 sensor 1)

Air induction system

EGR system

Fuel pressure

Injector

Gas leakage on exhaust system

ECM
HINT:

After confirming DTC P0125, use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage
output of A/F sensor from the CURRENT DATA.

The ECM controls the voltage of the AF+ and AF± terminals of the ECM to the fixed voltage. Therefore,
it is impossible to confirm the A/F sensor output voltage without OBD II scan tool or TOYOTA hand±
held tester.
DI1JU±04

± DIAGNOSTICSENGINE
DI±49
DTC P0171 System too Lean (Fuel Trim)
DTC P0172 System too Rich (Fuel Trim)
CIRCUIT DESCRIPTION
Fuel trim refers to the feedback compensation value compared to the basic injection time. Fuel trim includes
short±term fuel trim and long±term fuel trim.
Short±term fuel trim is the short±term fuel compensation used to maintain the air±fuel ratio at its ideal
theoretical value.
The signal from the A/F sensor is approximately proportional to the existing air±fuel ratio, and ECM compar-
ing it with the ideal theoretical value, the ECM reduces fuel volume immediately if the air±fuel ratio is rich
and increases fuel volume if it is lean.
Long±term fuel trim compensates for the deviation from the central value of the short±term fuel trim stored
up by each engine tolerance, and the deviation from the central value due to the passage of time and
changes of environment.
If both the short±term fuel trim and long±term fuel trim exceed a certain value, it is detected as a malfunction
and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
When air±fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on RICH side
(2 trip detection logic)

Air induction system

Injector blockage

Manifold absolute pressure sensor

Engine coolant temp. sensor

Fuel shutoff valve for delivery pipe

Gas leakage on exhaust system

Air induction system

Open or short in A/F sensor (bank 1 sensor 1) circuit

A/F sensor (bank 1 sensor 1)

ECM
P0172
When air±fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)

Injector leak, blockage

Manifold absolute pressure sensor

Engine coolant temp. sensor

Ignition system

Fuel shutoff valve for delivery pipe

Gas leakage on exhaust system

Open or short in A/F sensor (bank 1 sensor 1) circuit

A/F sensor (bank 1 sensor 1)

ECM
HINT:

When the DTC P0171 is recorded, the actual air±fuel ratio is on the LEAN side. When DTC P0172 is
recorded, the actual air±fuel ratio is on the RICH side.

If the vehicle runs out of fuel, the air±fuel ratio is lean and DTC P0171 is recorded. The MIL then comes
on.

If the total of the short±term fuel trim value and long±term fuel trim value is within +38 %, the system
is functioning normally.

The A/F sensor output voltage and the short±term fuel trim value can be read using the OBD II scan
tool or TOYOTA hand±held tester.
DI1JW±04

A00309
ECM Fuel Pressure Sensor
for Delivery Pipe
1PCNG2VC
E2 Y
G±BE5
E7
E5 3
25 V
E1 1
5
9
BR DI±56
± DIAGNOSTICSENGINE
DTC P0190 Fuel Rail Pressure Circuit Malfunction
CIRCUIT DESCRIPTION
By a built±in sensor unit, the fuel rail pressure sensor detects the intake manifold pressure as a voltage. The
ECM then determines the basic injection duration and basic injection advance angle based on this voltage.
Since the fuel rail pressure sensor does not use the atmospheric pressure as a criterion, but senses the ab-
solute pressure inside the intake manifold (the pressure in proportion to the present absolute vacuum 0),
it is not influenced by fluctuations in the atmospheric pressure due to high altitude and other factors. This
permits it to control the air±fuel ratio at the proper lever under all conditions.
DTC No.DTC Detecting ConditionTrouble Area
P0190Open or short in fuel pressure sensor circuit for delivery pipe

Open or short in fuel pressure sensor circuit for delivery pipe

Fuel pressure sensor for delivery pipe

ECM
HINT:
After confirming DTC P0190, use the OBD II scan tool or TOYOTA hand±held tester to confirm the fuel rail
pressure from the CURRENT DATA.
WIRING DIAGRAM
DI64V±01

A00407
Air
Air FilterAir
E
System: OFFSystem: ON GG E
± DIAGNOSTICSENGINE
DI±65
(b) There is a malfunction in the system.
If there is a malfunction in the system, the MIL will light up after steps (2) to (5) above are done. (2 trip
detection logic)
INSPECTION PROCEDURE
HINT:

If DTCs P0105, P0106 and P0400 are output simultaneously, perform troubleshooting of DTC P0105
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 was warmed up or not, the air±fuel
ratio was lean or rich, etc. at the time of the malfunction.
TOYOTA hand±held tester:
1 Check connection of vacuum hose and EGR hose (See Pub. No. RM654U, page
EC±12).
NG Repair or replace.
OK
2 Check VSV for EGR.
PREPARATION:
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand±
held tester main switch ON.
(c) Select the ACTIVE TEST mode on the TOYOTA hand±
held tester.
CHECK:
Check the operation of the VSV when it is operated by the TOY-
OTA hand±held tester.
OK:
EGR system is OFF:
Air from port E is flowing out through the air filter.
EGR system is ON:
Air from port E is flowing out port G.
OK Go to step 4.
NG
3 Check operation of VSV for EGR (See Pub. No. RM654U, page SF±43).

A09281
A09423
ON
E6 Connector
EGR
OFF
Air
FilterON
Air
E
G E
VSV is ON
VSV is OFF Air
G
± DIAGNOSTICSENGINE
DI±67
Check and replace ECM (See page IN±29).
OBD II scan tool (excluding TOYOTA hand±held tester):
1 Check connection of vacuum hose and EGR hose (See Pub. No. RM654U, page
EC±12).
NG Repair or replace.
OK
2 Check VSV for EGR.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Disconnect the E6 connector from the ECM.
(c) Turn the ignition switch ON.
CHECK:
Check the VSV function.
(1) Connect between terminal EGR of the ECM con-
nector and body ground (ON).
(2) Disconnect between terminal EGR of the ECM con-
nector and body ground (ON).
OK:
(1) VSV is ON:
Air from port E is flowing out through the air filter.
(2) VSV is OFF:
Air from port E is flowing out port G.
OK Go to step 4.
NG
3 Check operation of VSV for EGR (See Pub. No. RM654U, page SF±43).
NG Replace VSV for EGR.
OK

DI02U±04
Vehicle Brought to Workshop
Customer Problem Analysis
Check DTC and Freeze Frame Data (Precheck)
Record or Print DTC and Freeze Frame Data P.
DI±133
Clear DTC and Freeze Frame Data P. DI±133
Visual Inspection
Setting the Check Mode Diagnosis P.
DI±133
1
Items insideare titles of pages in this manual, with the
page number indicated in the bottom portion. See the indicated
pages for detailed explanations.
P.
DI±132
Connect an OBD II scan tool or TOYOTA hand±held tester to DLC3.
If the display shows ºUNABLE TO CONNECT TO VEHICLEº when you have connected the
scan tool / TOYOTA hand±held tester, inspect DLC3 P.
DI±133
2
3
4
5
6
Symptom does not occur
Problem Symptom Confirmation8
7Symptom Simulation
P.
IN±19Symptom occurs
DTC CheckP. DI±133OK Code11Preliminary Check
P.
DI±133
DTC Chart
P. DI±145Mechanical System Test
P.
DI±133
Manual Shifting Test
P.
DI±133 OK
OK
Chapter 1
(Electronic)Chapter 2
(On±Vehicle)
P.
DI±148 OK
Chapter 3
(Off±Vehicle)OK Problem Symptoms Table± P. DI±148
Circuit
Inspection
O/D Cancel Signal Check

O/D Main Switch & O/D OFF Indica-
tor Light Circuit Check
NG
Parts Inspection
NG
NGNG
Identification of ProblemRepairConfirmation TestEnd
NG
NG
12
13
14
15
16 17 9
10
P. DI±148P. DI±148
P. DI±151 to DI±171
OK
± DIAGNOSTICSAUTOMATIC TRANSAXLE
DI±131
201 Author: Date:
AUTOMATIC TRANSAXLE
HOW TO PROCEED WITH TROUBLESHOOTING