2003 HONDA CIVIC ECT sensor

sRs
Precautions and Procedures (cont'dl
Disconnecting System Connectors
Before removing a front airbag. side airbag, or other SRS related devices {the SRS unit, the cable reel, the front impact
sensors, the side impact sensors, the seat belt buckle tensioners, and the seat belt tensioner connector), disconnectingconnectors from related devices, or removing the dashboard or the steering column, disconnect the airbag connectorsor the side airbag connectors to prevent accidental deploVment.
Turn the ignition switch OFF, disconnect the negative cable from the battery, and wait at least 3 minutes before
beginning the following procedures.'BeforedisconnectingSRSunitconnectorA(1)fromtheSRSunit,disconnectthedriver'sairbag4Pconnector(3).
the front passenger's airbag 4P connector (4), the driver's seat belt tensioner 2P connector (6), and the frontpassenger's seat belt tensioner 2P connector (7).
. Before disconnecting SRS unit connector B (8) from the SRS unit, disconnect both side airbag 2P connectors (11. '12),
and both seat belt buckle tensioner 4P connectors (9, 10).. Before disconnecting the cable reel 4P connector (2), disconnect the driver's airbag 4P connector (3).'Beforedisconnectingthefloorwireharness4Pconnector(5),disconnectbothseatbelttensioner2Pconnectors
(6.7).
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DTCDetection ltemNotes9-1Internal failure of the SRS unit. lf intermittent, it could mean internalfailure of the unit or a faulty indicator circuit. Refer toTroubleshooting Intermittent Failures (see page 23-26).
NOTE: Before troubleshooting DTC 9-1 or 9-2, check battery/systemvoltage. lf the voltage is low, repair the charging system beforetroubleshooting the SRS.
(see page 23-69)
9-2Internal failure of the SRS unit. lf intermittent, it could mean internalfailu re of the power supply (VB line). Refer to TroubleshootingIntermittent Failures (see page 23-26).
NOTE: Before troubleshooting DTC 9-1 or 9-2, check battery/systemvoltage. lf the voltage is low, repair the charging system or replacethe b€ttery before troubleshooting the SRS.
9-3Faulty driver's seat belt buckle switch(see Daqe 23-71)9-4
9-6
FaultLtglt passenger's seat belt buckle switch
Faulty Ieft front imDact sensorlgqgfage 23-74)
{see Daqe 23-77)9-7Faulty right front impact sensor(see paqe 23-79)10-1Seat belt and seat belt buckle tensioners (and airbag(s)) deployedDriver's side airbag deployed
Seat belt and seat belt buckle tensioners (and airbag(s)) and driver'sside airbag deployed
Front passenqer's side airbao deDloved
(see page 23-69)10-2
r0-3
'10-4
'10-5Seat belt and seat belt buckle tensioners (and airbag(s)) and frontpassenqer's side airbaq deDloved
10-6Driver's and front passenqer's side al10-7Seat belt and seat belt buckle tensioners (and airbag(s)) and driver'sand front passenger's side airbags deployed
1 1-1Open or increased resistance in driver's side airbao inflator(see paqe 23-81)Short to another wire or decreased resistance in driver's side airbaoinflator
(see page 23-82)
11-4Short to power in driver's side airbaq inflator(see oaqe 23-83)I t-5Short to ground in driver's side airbaq inflator{see paqe 23-85)Open or increased resistance in front passenger's side airbaginflator
(see page 23-86)
Short to another wire or decreased resistance in front passenger's
side airbag inflator
(see page 23-87)
12-4Short to power in front passenqer's side airbaq inflator{see Daqe zJ-uu}I z-5Short to ground in front passenger's side airbaq inflator(see oaqe 23-90)13-1Internal failure of the driver's side impact sensor(see page 23-70)
No signal from the driver's side impact sensor(see paqe 23-91)13-4
14-1-7ii,
Faulty power supply to the df,rglllug t Opact s9I99LInternal failure ofthe front passenger's side impact sensor
(see page 23-92)(see page 23-70)
14-3No signal from the front passenger's side impact sensor(see paqe 23-94)14-4Faulty power supply to the front passenqer's side impact sensor(see page 23-95)15-1Faultv OPDS unit or OPDS not initialized(see paqe 23-96115-2Faulty side airbag cutoff indicator circuit(see Daqe 23-99)15-3Faulty OPDS sensor(see oaoe 23-104)
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ISystem Description
SRS Components
Airbags
The SRS is a safety device which, when used with the seat belt, is designed to help protect the driver and frontpassenger in a frontal impact exceeding a certain set limit. The system consists ofthe SRS unit, including safingsensor and impact sensor (A), the cable reel (B), the driver's airbag (C), the front passenger,s airbag (D). seat belttensioners (l), seat belt buckle tensioners (J), and front impact sensors (K).
Since the driver's and front passenger's airbags use the same sensors, both normally inflate at the same ttme.However, it is possible for only one airbag to inflate. This can occur when the severity of a collision is at the margin, orthreshold, that determines whether or not the airbags will deploy. In such cases, the seat belt will provide sufficientprotection, and the supplemental protection offered by the airbag would be mininal.
Side Airbags
The side airbags (E) are in each front seat-back. They help protect the upper torso of the driver or front seat passenger
during a moderate to severe side impact. Side impact sensors (F) in each door sill and in the SRS unit detect such animpact and instantly inflate the driver's or the passenger's side airbag. Only one side airbag will deploy during a sideimpacl. lf the impact is on the passenger's side, the passenger's side airbag will deploy even if there is no passenger.
Seat Belt and Seat Belt Buckle Tensioners
The seat belt and seat belt buckle tensioners are linked with the SRS airbags to further increase the effectiveness ofthe seat belt. ln a front-end collision, the tensioners instantly retract the belt and buckle firmly to secure the occupantsin their seats.
OPDS
The side airbag system also includes an occupant position detection system (OpDS). This system consists of sensors(G)and an OPDS unit (H) in the front passenger's seat-back. The OPDS unit sends occupant heighl and position data tothe SRS unit. lf the OPDS unit determines that the front passenger is of small stature (for example, a child) and thefront passenger is leaning into the side airbag deployment path, the SRS unit will automatically disable the passenger'sside airbag. The SRS unit will also disable the airbag when the OPDS detects certain obiects on the seat. When theside airbag is disabled, the side airbag cutoff indicator on the instrument panel alerts the driver that the passenger'sside airbag will not deploy in a side impact. When the object is removed, or the passenger sits upright, the side airbagcutoff indicator will go off after a few seconds, alerting the driver that the passenger's side airbag will deploy in a sideimDact.
(cont'd)
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sRs
System Description (cont'dl
SRS Operation
The main circuit in the SRS unit senses and judges the force of impact and, if necessary. ignites the inflator charges. lf
battery voltage is too low or power is disconnected due to the impact, the voltage regulator and the back-up power
circuit, respectively, will keep voltage at a constant level.
For the SRS to operate:
Seat Belt Tensioners and Seat Belt Buckle Tensioners
(1) A front impact sensor must activate and send electric signals to the microprocessor.
(2) The microprocessor must compute the signals and send them to the tensioners.
(3) The charges must ignite and deploy the tensioners.
Driver's and Front Passenger's Airbagls)
(1) A front impact sensor musl activate. and send electric signals to the microprocessor.
(2) The microprocessor must compute the signals. and depending on the severity of the collision and whether the seat
belt buckle swilch is ON or OFF, it sends the appropriate signals to the airbag inflator(s).
(3) The inflators that received signals must ignite and deploy the airbags.
Side Airbaglsl( 1) A side impact sensor must activate, and send electric signals to the microprocessor.
(2) The microprocessor must compute the signals and send them to the side airbag inflator(s). However, the
microprocessor cuts off the signals to the front passenger's side airbag if the OPDS unit determines that the tront
passenger's head is in the deployment path of the side airbag.
(3) The inflator that received the signal must ignite and deploy the side airbag.
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DTC 9-6: Faulty Left Front lmpact Sensor
Special Tools Required. SRS inflator simulator 07SAZ-TB4011A. SRS simulator lead H 07YM-S3AA100
1. Erase the DTC memory (see page 23-26).
2. Turn the ignition switch ON (ll), and check that the
SRS indicator comes on for about 6 seconds and
then goes off.
Does the SRS indicator stay on?
YES-Go to step 3.
NO Intermiftent failure, system is OK at this time.
Go to Troubleshooting Intermittent Failures (see
page 23-26).
3. Turn the ignition switch OFF. Check the
connections between SRS unit connector A (18P)
and the SRS unit. between the engine
compartment wire harness 2P connector and the
left front impact sensor {see page 23-13), and at
connector C401.
Are the connections OK?
YES Go to step 4.
NO-Repair the poor connections and retest. lf DTC
9-6 is still present, go to step 4.
Turn the ignition switch OFF. Disconnect the
battery negative cable. and wait for 3 minutes.
Disconnect the driver's airbag 4P connector from
the cable reel (see step 2 on page 23-21).
Disconnect the front passenger's airbag 4P
connector from dashboard wire harness B {see step
3 on page 23-21).
Disconnect both seat belt tensioner 2P connectors
from the floor wire harness (see step 5 on page 23-
22).
7.
9.
10.
8. Disconnect the engine compartment wire harness
2P connector {A) from the left front impact sensor.
Disconnect SRS unit connector A {18P) from the
SRS unit (see step 7 on page 23-22J.
Check resistance between the No. 10 and No. 11
terminals of SRS unit connector A (18P). There
should be an oDen circuit. or at least 1 M 0 .
SRS UNIT CONNECTOR A (18PI
Wire side of female terminals
ls the resistance as specitied?
YES Go to step 1 1.
NO-Short in the engine companment wire
harness or dashboard wire harness B; replace the
faulty harness.I
Reconnect the battery negative cable.
Turn the ignition switch ON { ll).
{cont'd}
RED
11.
12.
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sRs
DTC Troubleshooting (cont'dl
13. Check voltage between the No. 10 terminal of SRS
unit connector A (18P) and body ground. There
shouid be 'l V or less.
SRS UNIT CONNECTOR A {,I8P)
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Wire side oI female terminals
ls the voltage as specitied?
YES-Go to step 14.
NO-Short to power in the engine compartment
wire harness or dashboard wire harness B; replace
the faulty harness.l
Turn the ignition switch OFF.
Connect the SRS inflator simulator (jumper
connector) and simulator lead H to the engine
compartment wire harness 2P connector (A).
07YAZ-S3AA100
07SAZ-TB,O11A
14.
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16. Check resistance between the No. 10 and No. 11
terminals of SRS unit connector A (18P). There
should be 1 0 or less.
SRS UNIT CONNECTOR A Il8PI
Wire side of female terminals
ls the rcsistance as specified?
YES Faulty left front impact sensor or SRS unit;
replace the left front impact sensor (see page 23-125).
lf the problem is still present, replace the SRS unit(see page 23-122).1
NO-Poor connection at C401, faulty engine
compartment wire harness, or faulty dashboard
wire harness B. Inspect C401. lf it is OK, replace the
faulty harness.l
= \y,

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DTC 9-7: Faulty Right Front lmpact Sensor
Special Tools Bequired. SRS inflator simulator 07SAZ-TB4011A. SRS simulator lead H 07YM-S3AA100
1. Erase the DTC memory {see page 23-26).
2. Turn lhe ignition switch ON {ll), and checkthatthe
SRS indicator comes on for about 6 seconds and
then goes off.
Does the SRS indicator stay on?
YES-Go to step 3.
NO Intermittent failure, system is OK at this time.
Go to Troubleshooting Intermittent Failures (see
page 23-26).
3. Turn the ignition switch OFF. Check the
connections between SRS unit connectorA (18P)
and the SRS unit, between the engine
compartment wire harness 2P connector and the
right front impact sensor (see page 23-13), and at
connector C401.
Are the connections OK?
YES-Go to step 4.
NO Repair the poor connections and retest. lf DTC
9-7 is still present, go to step 4.
Turn the ignition switch OFF. Disconnect the
battery negative cable, and wait for 3 minutes.
Disconnect the driver's airbag 4P connector from
the cable reel {see step 2 on page 23-21).
Disconnect the front passenger's airbag 4P
connector from the dashboard wire harness (see
step 3 on page 23-21).
Disconnect both seat belt tensioner 2P connectors
from the floor wire harness (see step 5 on page 23-
22).
4.
5.
7.
I
'10.
Disconnect the engine compartment wire harness
2P connector (A) from the right front impact sensor.
Disconnect SRS unit connector A (18P) from the
SRS unit (see step 7 on page 23-221.
Check resistance between the No. 1 and No. 12
terminals of SRS unit connector A (18P). There
should be an open circuit, or at least 1 M 0.
SRS UNIT CONNECTOR A (18PI
GRN
11.
Wire side ol female terminals
ls the resistance as specified?
YES Go to step 11.
NO-Short in the engine companment wire
harness or dashboard wire harness B; replace the
faulty harness,I
Reconnect the battery negative cable.
Turn the ignition switch ON (ll).
(cont'd)
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23-79

sRs
DTC Troubleshooting (cont'd)
13. Check voltage between the No. 1terminal ofSRS
unit connector A (18P) and body ground. There
should be 1 V or less.
SRS UNIT CONNECTOR A I18P}
Wire side of female terminals
ls the voltage as specified?
YES Go to step 14.
NO-Short to power in the engine compartment
wire harness or dashboard wire harness B; replace
the faulty harness.l
Turn the ignition switch OFF.
Connect the SRS inflator simulator (jumper
connector) and simulator lead H to the engine
compartment wire harness 2P connector (A).
14.
07YAZ-S3AA100
23-80
16. Check resistance between the No. 1 and No. '12
terminals of SRS unit connector A (18P). There
should be 1 O or less.
SRS UNIT CONNECTOR A {18P)
GRN
Wire side of female terminals
ls the resistance as specitied?
YES Faulty right front impact sensor or SRS unit;
replace the rightfront sensor {see page 23-125). lfthe
problem is still present, replace the SRS unit (see
page 23-1221.a
NO- Poor connection at C401, faulty engine
compartment wire harness, or faulty dashboard
wire harness B. lnspect C401. lf it is OK, replace the
faulty harness, I
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