2007 TOYOTA SIENNA ecu harness

IN–36INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
IN
HOW TO PROCEED WITH
TROUBLESHOOTING
1. OPERATION FLOW
HINT:
Perform troubleshooting in accordance with the
procedures below. The following is an outline of basic
troubleshooting procedures. Confirm the troubleshooting
procedures for the circuit you are working on before
beginning troubleshooting.
NEXT
(a) Ask the customer about the conditions and environment
when the problem occurred.
NEXT
Standard voltage:
11 to 14 V
If the voltage is below 11 V, recharge or replace the
battery before proceeding.
NEXT
(a) Visually check the wire harnesses, connectors and fuses
for open and short circuits.
(b) Warm up the engine to the normal operating
temperature.
(c) Confirm the problem symptoms and conditions, and
check for DTCs
Result
B
A
1VEHICLE BROUGHT TO WORKSHOP
2CUSTOMER PROBLEM ANALYSIS
3INSPECT BATTERY VOLTAGE
4SYMPTOM CONFIRMATION AND DTC (AND FREEZE FRAME DATA) CHECK
Result Proceed to
DTC is output A
DTC is not output B
Go to step 6

INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMSIN–41
IN
If a DTC was displayed in the initial DTC check, the
problem may have occurred in a wire harness or
connector in that circuit in the past. Check the wire
harness and connectors.
B
A
The problem still occurs in a place other than the diagnostic
circuit (the DTC displayed first is either for a past problem or
a secondary problem).
4. SYMPTOM SIMULATION
HINT:
The most difficult case in troubleshooting is when no
problem symptoms occur. In such a case, a thorough
problem analysis must be carried out. A simulation of the
same or similar conditions and environment in which the
problem occurred in the customer's vehicle should be
carried out. No matter how much skill or experience a
technician has, troubleshooting without confirming the
problem symptoms will lead to important repairs being
overlooked and mistakes or delays.
For example:
With a problem that only occurs when the engine is
cold or as a result of vibration caused by the road
during driving, the problem can never be
determined if the symptoms are being checked on
a stationary vehicle or a vehicle with a warmed-up
engine. Vibration, heat or water penetration
(moisture) is difficult to reproduce. The symptom
simulation tests below are effective substitutes for
the conditions and can be applied on a stationary
vehicle. Important points in the symptom
simulation test:
In the symptom simulation test, the problem
symptoms as well as the problem area or parts
must be confirmed. First, narrow down the
possible problem circuits according to the
symptoms. Then, connect the tester and carry out
the symptom simulation test, judging whether the
circuit being tested is defective or normal. Also,
confirm the problem symptoms at the same time.
Refer to the problem symptoms table for each
system to narrow down the possible causes.SYSTEM NORMAL
TROUBLESHOOTING OF EACH PROBLEM SYMPTOM

IN–42INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
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(a) VIBRATION METHOD: When a malfunction seems
to occur as a result of vibration.
(1) PART AND SENSOR
Apply slight vibration with a finger to the part of
the sensor suspected to be the cause of the
problem, and check whether or not the
malfunction occurs.
NOTICE:
Applying strong vibration to relays may open
relays.
(2) CONNECTORS
Slightly shake the connector vertically and
horizontally.
(3) WIRE HARNESS
Slightly shake the wire harness vertically and
horizontally.
HINT:
The connector joint and fulcrum of the vibration
are the major areas that should be checked
thoroughly.
(b) HEAT METHOD: When a malfunction seems to
occur when the area in question is heated.
(1) Heat the component that is the possible cause of
the malfunction with a hair dryer or similar
device. Check if the malfunction occurs.
NOTICE:
• Do not heat to more than 60
C (140F).
Exceeding this temperature may damage
the components.
• Do not apply heat directly to the parts in
the ECU.
(c) WATER SPRINKLING METHOD: When a
malfunction seems to occur on a rainy day or in
high-humidity.
(1) Sprinkle water onto the vehicle and check if the
malfunction occurs.
NOTICE:
• Never sprinkle water directly into the
engine compartment. Indirectly change
the temperature and humidity by spraying
water onto the front of the radiator.
• Never apply water directly onto the
electronic components.
HINT:
If the vehicle has or had a water leakage
problem, the leakage may have damaged the
ECU or connections. Look for evidence of
corrosion or short circuits. Proceed with caution
during water tests.B071602E03
D025085E02

IN–44INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
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Inspection Procedures Use the inspection procedures to determine if the circuit is normal or
abnormal. If abnormal, use the inspection procedures to determine
whether the problem is located in the sensors, actuators, wire
harnesses or ECU.
Indicates the condition of the connector of the ECU during the check Connector being checked is connected.
Connections of tester are indicated by (+) or (-) after the terminal
name.
Connector being checked is disconnected.
The inspections between a connector and body ground, information
about the body ground is not shown in the illustration. Item Description

INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMSIN–31
IN
ELECTRONIC CIRCUIT INSPECTION
PROCEDURE
1. BASIC INSPECTION
(a) WHEN MEASURING RESISTANCE OF
ELECTRONIC PARTS
(1) Unless otherwise stated, all resistance
measurements should be made at an ambient
temperature of 20
C (68F). Resistance
measurements may be inaccurate if measured
at high temperatures, i.e. immediately after the
vehicle has been running. Measurements should
be made after the engine has cooled down.
(b) HANDLING CONNECTORS
(1) When disconnecting a connector, first squeeze
the mating connector housing halves tightly
together to release the lock, and then press the
lock claw and separate the connector.
(2) When disconnecting a connector, do not pull on
the harnesses. Grasp the connector directly and
separate it.
(3) Before connecting a connector, check that there
are no deformations, damage, looseness or
missing terminals.
(4) When connecting a connector, press firmly until
it locks with a "click" sound.
(5) If checking a connector with a TOYOTA
electrical tester, check the connector from the
backside (harness side) using a mini test lead.
NOTICE:
• As a waterproof connector cannot be
checked from the backside, check it by
connecting a sub-harness.
• Do not damage the terminals by moving
the inserted tester needle.
(c) CHECKING CONNECTORS
(1) Checking when a connectors is disconnected:
Squeeze the connector together to confirm that
they are fully connected and locked.
(2) Checking when a connector is disconnected:
Check by pulling the wire harness lightly from
the backside of the connector. Look for
unlatched terminals, missing terminals, loose
crimps or broken conductor wires. Check
visually for corrosion, metallic or foreign matter
and water, and bent, rusted, overheated,
contaminated, or deformed terminals.
D032092E01
D025087E03

IN–32INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
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(3) Checking the contact pressure of the terminal:
Prepare a spare male terminal. Insert it into a
female terminal, and check for ample tension
when inserting and after full engagement.
NOTICE:
When testing a gold-plated female terminal,
always use a gold-plated male terminal.
(d) REPAIR METHOD OF CONNECTOR TERMINAL
(1) If there is any foreign matter on the terminal,
clean the contact point with compressed air or a
cloth. Never rub the contact point using
sandpaper as the plating may come off.
(2) If there is abnormal contact pressure, replace
the female terminal. If the male terminal is gold-
plated (gold color), use a gold-plated female
terminal; if it is silver-plated (silver color), use a
silver-plated female terminal.
(3) Damaged, deformed, or corroded terminals
should be replaced. If the terminal does not lock
into the housing, the housing may have to be
replaced.
(e) HANDLING OF WIRE HARNESS
(1) If removing a wire harness, check the wiring and
clamping before proceeding so that it can be
restored in the same way.
(2) Never twist, pull or slacken the wire harness
more than necessary.
(3) The wire harness should never come into
contact with a high temperature part, or rotating,
moving, vibrating or sharp-edged parts. Avoid
contact with panel edges, screw tips and other
sharp items.
(4) When installing parts, never pinch the wire
harness.
(5) Never cut or break the cover of the wire harness.
If it is cut or broken, replace it or repair it with
vinyl tape.
2. CHECK FOR OPEN CIRCUIT
(a) For an open circuit in the wire harness in Fig. 1, the
resistance or voltage, as described below.
D025088E02
D032093E01
D032094E01
Z017004E02

INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMSIN–33
IN
(b) Check the resistance.
(1) Disconnect connectors A and C and measure
the resistance between the terminals of the
connectors.
Standard resistance (Fig. 2)
HINT:
Measure the resistance while lightly shaking the
wire harness vertically and horizontally. If the
results match the examples above, an open
circuit exists between terminal 1 of connector A
and terminal 1 of connector C.
(2) Disconnect connector B and measure the
resistance between the terminals of the
connectors.
Standard resistance (Fig. 3)
If the results match the examples above, an
open circuit exists between terminal 1 of
connector B2 and terminal 1 of connector C.
(c) Check the voltage.
(1) In a circuit in which voltage is applied to the ECU
connector terminal, an open circuit can be
checked by conducting a voltage check.
With each connector still connected, measure
the voltage between the body ground and these
terminals (in this order): 1) terminal 1 of
connector A, 2) terminal 1 of connector B, and 3)
terminal 1 of connector C.
Standard voltage (Fig. 4)
If the results match the examples above, an
open circuit exists in the wire harness between
terminal 1 of connector B and terminal 1 of
connector C.
Z017005E02
Tester Connection Specified Condition
Connector A terminal 1 - Connector
C terminal 110 k
or higher
Connector A terminal 2 - Connector
C terminal 2Below 1
B004722E03
Tester connection Specified Condition
Connector A terminal 1 - Connector
B1 terminal 1Below 1
Connector B2 terminal 2 - Connector
C terminal 210 k or higher
Z017007E02
Tester Connection Specified Condition
Connector A terminal 1 - Body
ground5 V
Connector B terminal 1 - Body
ground5 V
Connector C terminal 1 - Body
groundBelow 1 V

IN–34INTRODUCTION – HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
IN
3. CHECK FOR SHORT CIRCUIT
(a) If the wire harness is ground shorted (Fig. 5), locate
the section by conducting a resistance check with
the body ground (below).
(b) Check the resistance with the body ground.
(1) Disconnect connectors A and C and measure
the resistance.
Standard resistance (Fig. 6)
HINT:
Measure the resistance while lightly shaking the
wire harness vertically and horizontally. If your
results match the examples above, an open
circuit exists between terminal 1 of connector A
and terminal 1 of connector C.
(2) Disconnect connector B and measure the
resistance.
Standard resistance (Fig. 7)
If the results match the examples above, a short
circuit exists between terminal 1 of connector B2
and terminal 1 of connector C.
4. CHECK AND REPLACE ECU
NOTICE:
• The connector should not be disconnected from
the ECU. Perform the inspection from the
backside of the connector on the wire harness
side.
• When no measuring condition is specified,
perform the inspection with the engine stopped
and the ignition switch on.
• Check that the connectors are fully seated. Check
for loose, corroded or broken wires.
Z017008E02
Z017009E02
Tester Connection Specified Condition
Connector A terminal 1 - Body
groundBelow 1
Connector A terminal 2 - Body
ground10 k or higher
Z017808E02
Tester Connection Specified Condition
Connector A terminal 1 - Body
ground10 k
or higher
Connector B2 terminal 2 - Body
ground Below 1