Toyota Sequoia (2005). Manual — part 162
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DIAGNOSTICS
ENGINE
DI–443
637
TYPICAL ENABLING CONDITIONS
It
Specification
Item
Minimum
Maximum
The monitor will run whenever these
DTCs are not present
See page
Battery voltage
8 V
–
Ignition switch
ON
Starter
OFF
Engine
Running
TYPICAL MALFUNCTION THRESHOLDS
Detection Criteria
Threshold
Soak time measurement when ECM CPU clock counts 10
min.
Less than 7 min., or more than 13 min.
INSPECTION PROCEDURE
HINT:
DTC P2610 is set if an internal ECM problem is detected. Diagnostic procedures are not required. ECM
replacement is required.
Read freeze frame data using a hand–held tester. Freeze frame data record the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle
was moving or stationary, if the engine was warmed up or not, if the air–fuel ratio was lean or rich, and
other data, from the time the malfunction occurred.
1
Replace ECM (See page
).
NEXT
Check whether DTC output recurs.
(a)
Connect a hand–held tester to the DLC3.
(b)
Turn the ignition switch to ON.
(c)
Clear DTCs (see page
(d)
Start the engine and wait for 10 minutes or more.
(e)
On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PEND-
ING CODES.
(f)
If no pending DTC is displayed, the repair has been successfully completed.
DI–444
–
DIAGNOSTICS
ENGINE
638
DTC
U0001
High Speed Can Communication Circuit
CIRCUIT DESCRIPTION
The engine control unit and the transmission control unit are located inside the ECM. The engine control unit
intercommunicates with the transmission control ECU with the Controller Area Network (CAN).
If there is a problem in this intercommunication, the ECM sets a DTC.
DTC No.
DTC Detection Condition
Trouble Area
U0001
The following conditions are met for 2 seconds (1 trip detection
logic):
(a) Ignition switch ON
(b) Battery voltage is 10 V or more
(c) No intercommunication between engine control ECU and
transmission control ECU
ECM
INSPECTION PROCEDURE
Replace ECM (See page
DID8J–01
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DIAGNOSTICS
ENGINE
DI–445
639
DTC
P043E
Evaporate Emission System Reference Ori-
fice Clog Up
DTC
P043F
Evaporate Emission System Reference Ori-
fice High Flow
DTC SUMMARY
DTCs
Monitoring Items
Malfunction Detection Conditions
Trouble Areas
Detection
Timings
Detection
Logic
P043E
0.02 inch orifice clogged
Vacuum pump creates negative pressure
through 0.02 inch orifice, and EVAP system
pressure is measured to determine leak
pressure standard. 0.02 inch leak pressure
standard is measured at the start and at the
end of the leak check.
If system pressure lower than –4.85 kPa
(–36.38 mmHg)*, ECM determines that
0.02 inch orifice has clogging malfunction.
Pump module
Connector/Wire harness
(Pump module – ECM)
ECM
Leakage from EVAP sys-
tem
While
ignition
switch is
OFF
2 trip
P043F
0.02 inch orifice high–flow
Vacuum pump creates negative pressure
through 0.02 inch orifice, and EVAP system
pressure is measured to determine leak
pressure standard. 0.02 inch leak pressure
standard is measured at the start and at the
end of the leak check.
If system pressure higher than –1.06 kPa
(–7.95 mmHg)*, ECM determines that 0.02
inch orifice has high–flow malfunction.
Pump module
Connector/Wire harness
(Pump module – ECM)
ECM
Leakage from EVAP sys-
tem
While
ignition
switch is
OFF
2 trip
*: The threshold values vary according to the atmospheric pressure measured at EVAP monitor beginning.
The values described in the table above are based on an atmospheric pressure of 100 kPa (750.1 mmHg)
(absolute pressure).
HINT:
The 0.02 inch orifice is located inside the pump module.
CIRCUIT DESCRIPTION
The circuit description can be found in the EVAP (Evaporative Emission) Inspection Procedure (see page
DID8I–01
A23480
Fuel Tank
Canister
Vacuum Pump: OFF
Pressure Sensor
0.02 Inch Orifice
Pump Module
Operation A: Atmospheric Pressure Measurement
Vent Valve: OFF (vent)
Operation D: Purge VSV monitor
Operation B: 0.02 Inch Leak Pressure Measurement
Negative
Pressure
Atmospheric
Pressure
Operation C: EVAP Leak Check
Air Filter
Purge VSV: OFF
OFF (vent)
ON
OFF
OFF
ON
ON (closed)
ON
ON
ON (closed)
DI–446
–
DIAGNOSTICS
ENGINE
640
MONITOR DESCRIPTION
5 hours* after the ignition switch is turned OFF, the electric vacuum pump creates negative pressure (vacu-
um) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions
based on the EVAP pressure.
HINT:
*: If the engine coolant temperature is not below 35
C (95
F) after 5 hours after the ignition switch is turned
off, the monitor check starts 2 hours later. If it is still not below 35
C (95
F) 7 hours after the ignition switch
is turned off, the monitor check starts 2.5 hours later.
Sequence
Operations
Descriptions
Duration
–
ECM activation
Activated by soak timer, 5 hours (7 or 9.5 hours) after ignition switch turned to OFF.
–
A
Atmospheric pressure
measurement
Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to
register atmospheric pressure.
If EVAP pressure is not between 70 kPa and 110 kPa (525 mmHg and 825 mmHg), ECM
cancels EVAP system monitor.
10 seconds
B
First 0.02 inch leak
pressure measure-
ment
In order to determine 0.02 inch leak pressure standard, vacuum pump creates negative pres-
sure (vacuum) through 0.02 inch orifice and then ECM checks if vacuum pump and vent
valve operate normally.
60 seconds
C
EVAP system pres-
sure measurement
Vent valve turned ON (closed) to shut EVAP system.
Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then
measured.
Write down the measured value as it will be used in the leak check.
If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor.
15 minutes*
D
Purge VSV monitor
Purge VSV opened and then EVAP system pressure measured by ECM.
Large increase indicates normal.
10 seconds
E
Second 0.02 inch leak
pressure measure-
ment
Leak check is performed after second 0.02 inch leak pressure standard is measured.
If stabilized system pressure higher than second 0.02 inch leak pressure standard, ECM
determines that EVAP system leaking.
60 seconds
F
Final check
Atmospheric pressure measured and then monitoring result recorded by ECM.
–
* If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.
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