Toyota Sequoia (2005). Manual - part 162

–

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 

DI–18

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 

SF–80

).

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 

DI–43

).

(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 

SF–80

)

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

DI–460

).

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.

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* If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.