1999 HONDA CIVIC pan

Emission Control System
Evaporative Emission (EVAP) Gontrols (cont'd)
'99 - 0O models only:
The scan tool indicates Diagnostic Trouble Code (DTC) P0451: The Fuel Tank Pressure sensor circuit range/oerformance Droblem.
ECM/PCM CONNECTORS
wire side ot femare terminars sG2 IGRN/BLK)
FUEL TANKPRESSURESENSOR
VACUUMPUMP/GAUGE,0 - 30 in.Hg
FUEL TANKPRESSURE SENSORASSEMBLY
EVAP TWOWAY VALVE
IJ
tl'
Ths MIL has been reDortgd on.DTC m/$1 i3 stored.
Check the tuel tank pros3ure ser|-sor:1. Do the ECM/PCM Reset Proce-dure.2. Remove the tuellill cap.3. Turn the ignition switch ON (ll).4. N4onitor the FTP Sensor volt-age with the Honda PGMTester, or measure voltagebetween body ground andECN4/PCM connector terminalsA29 and C18.
ls there approx. 2.5 V7
Check tho tuel tank pressure !on-soa:1. Remove the fuel tank (seepage 11 2421.2. Remove the fuel tank pres-sure sensor assembly fromthe fueltank.3. Connect the fuel tank PressureSensor sub-harness 6P con-nector to the access panelside connector,4. Disconnect the hose betweenthe EVAP two way valvg andthe fuel tank pressure sensor atthe EVAP two way valve end.5. Connect a vacuum pump tothe open end ofthat hose.6. Turn the ignition switch ON (ll).7. Monitor the FTP Sensor volt,age with the Honda PGMTester, or measure voltagebetween ECM/PCM connectorterminals A29 and C18, andcarefully pump vacuum on thehose one stroke at a time.8. The voltage sho!ld smoothlydrop from the stading approx.2.5 V down to approx. '1.5 V.STOP applying vacuum whenthe voltage drops to approx. 1.5V or damage to the fuel tankpressure sensor may occur.
Does the voltage drop toapprox. 1.5 V and hold?
Sub3titute a known-good ECM/PCM and r6check. It symptom/indicltion 90e3 aw.y, replac\. th€original ECM/PCM.
A (32P)
A973X - 041 -
xxxxx
11-274

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Fuel Tank Pro3sure sensor 196 D16Y8 engine (coupe).'97 D15Y7 engine {coupe: KL model, sedan: KL (LX) modeu,'97
D16Y8 engine (coupe: all models, sedan: KL model, '98-all models) '99 - 00 D16Y5 engine with M/Tl:
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PTANK
{LT GRNI
vcc2(YEL/BLU}
Wire side oI female terminals
FUEL TANKPRESSURE SENSOR3P CONNECTOR (C7921
sG2IGRN/8LK)
Foc2l::il":"toolindicatesDiagnosticTroublecode(DTc)P0452:A|owvo|tageprob|emintheFue|TankPressure
The fuel tank pressure sensor converts fuel tank absolute pressure into electrical signals and inputs the EcM/PCM.
OUTPUTVOLTAGEtvt4.5
-? kPa(-50 mmHg,-2 in.Hg)
ECM/PCM CONNECTOR O I16P)
Wire side of female terminals
+7 kPs150 mmHg,2 in.Hg)
PRESSURE
(cont'd)
11-275
- The MIL has been reported on- DTC P0452 is stored.
Check the vacuum lines:
Check the vacuum lines of the
fuel tank pressure sensor for mis-
routing, leakage, breakage and
cloggrng.
Are the vacuum lines OK?
Problem v€ritication:1. Do the ECM/PCM Reset Proce
dure.2. Remove the luel fill caP.
3. Turn the ignition switch ON lll)4. Monitor the FTP Sensor volt_
age with the Honda PGM
Tester, or measure voltage
between bodY ground and
ECM/PCM terminal Dl5.lntermittent tailuro, sYstem i5 OK
dt this timo. Chock for Poot con-
neciion3 or loose wir* at C131
llocatod under right side ot dashl,
C4O1 (located .bove under'da3htuso/ielay box), C574 1C568)*
{located under acc€ss Panell.C792 lfuel tank pressule sen3or)
and EcM/PCM.
ls there approx. 2.5 V?
Check tol an op€n in wite (VCC2
line):1. Turn the ignition switch OFF
2. Reinstallthe fuel fill caP.3. Disconnect the fuel tank Pres'sure sensor 3P connector-4. Turn the ignition switch ON (ll)
5, Measure voltage between the
fuel tank pressure sensor 3P
connector No. l terminal and
No. 2 terminal.
Repair open in the wite betweenthe fuel tank Pr€s3ure a€n3or andth6 EcM/PcM (D1ol.ls there approx. 5 V?
(To page 11'276)

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'99 - 00 models excepi Dl6Y5 engine with M/T:
The scan tool indicates Diagnostic Trouble Code (DTC) P0452: A low voltage problem in the Fuel Tank Pressure
sensor.
The fuel tank pressure sensor converts fuel tank absolute pressure into electrical signals and inputs the ECM/PCM
OUTPUTVOLTAGE(vlt.5
0.5-7 kP.(-g) mmHg,-2 in.Hgl
+7 kP.
150 mmHg,2 in.Hgl
PRESSURE
I
Wire side of lemale terminals
FUEL TANKPRESSURE SENSORSUB.HARNESS6P CONNECTOR (C574 (C568)rl
vcc2(YEL/BLUIsG2{GRN/BLK}
Wire side o{ temale terminals
The MIL has been .eported on.
DTC P0452 is stored
Check the vacuum lines:
Check the vacuum lines of the
fuel tank pressure sensor lor mis-
routing, leakage, breakage and
cloggrng.
Are the vacuum hnes OK?
Problem veritication:1. Do the ECM/PCM Reset Proce-
du re,2. Bemove the fuel fill caP.
3. Turn the ignition switch ON {ll)
4. Monitorthe FTP Sensor voltage
with the Honda PGM Tester' or
measure voltage between body
groLrnd and ECM/PCM connec_
tor terminalA29.
lntermitlent tailure, 3Ystem b OK
at this time. Check for Poor con'
nections or loose wire3 at C131
{located under right side of dash},
C401 {located above under'dash
tuse/relay box), C574 (C568)*
llocdted under access Panel),C792 (tuel rank Prcssure sensorl
and ECM/PCM.
ls there approx.2 5 V?
Check for an open in wire {VCC2
line):1. Turn the ignition switch OFF.
2. Reinstall the ltrel fill caP
3, Remove the access Panel from
the floor.4. Disconnect the fuel tank Pres'sure sensor sub-harness 6P
5. Turn the ignition switch ON (ll).
6. At the access Panel side, mea_
sure voltage between the fuel
tank Pressure sensor sub-nar-
ness 6P connector No 5termi
nal and No. 6 termlnal.
Repair open in tho wire between
th6 fu€l tank Prossuro sen3oa and
the ECM/PCM lc28).ls there approx 5 V?
ECM/PCM CONNECTOR A (32P)
PTANK {LT BLUI
I
ll
(To page '11-278)
(cont'd)

Emission Control System
Evaporative Emission (EVAPI Controls {cont,dlJ
FUEL TANKPRESSURE SENSORSU8-HABNESS6P CONNECTOR 1C574 tC568)rt
PTANK
{LT GRN}
PTANK
ILT GRN}
Wire side of female terminals
(From page 11-277)
Check for a short in the wire{PTANK line):At the access panel side, measure voltage between the fueltank pressure sensor sub-harness6P connector No. 2 terminal andNo. 6 terminal.
ls there approx. 5 V?
Chock lor a Short in the wi.e(PTANK line):1. Turn the ignition switch OFF.2. Disconnect the ECM/PCM con-nector A (32P).
3. Check for continuity betweenthe fuel tank pressure sensorsub-harness 6P connector No.2 terminals and body ground.
Repair short in the wi.e betwsenthe luel tank pressure sensor andECM/PCM {A291.
Subsiitute a known-good ECM/PCM and rechock. lf symptom/indication goes away, replac€ theoriginal ECM/PCM.
11-278

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Fue| Tank Pr€ssure sensor 196 Dr6Y8 engine (coupe},,97 D16Y7 angino (coupo: KL mode|' 3edan: KL (Lxl modg||',97
Dl6Y8 engine (coupe: all modeb, sedan: Ki model.'98'all modols) 39 - 0O Dl6Y5 ongins with M/Tl:
rFoG'l::;Jl"too|indicatesDiagnosticTroub|ecode(oTc)P0453;Ahighvo|tageprob|emintheFue|TankPressure
ECM/PCM CONNECTOR D Il6PI
PTANKILT GRNI
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Wire side of tgmale torminals
FUEL TANKPRESSURE SENSOR3P CONNECTOR (C792)
vcc2(YEL/BLU}
sG2(GRN/BLKI
Wire sid€ of female terminals
I
sG2IGRN/BLKI
PTANKIGBN/RED}
(cont'd)
11-279
The MIL has beon reponed on
DTC P0453 b stored.
Check the vacuum lines:
Check the vacuum lines oI the
fueltank pressure sensor for mis-
routing, leakage, breakage and
clogging.
Are the vacuum lines OK?
Problem verification:1. Do the ECM/PCM Reset Proce-
dure.2. Femove the fuel fill cap
3. Turn the ignition switch oN (ll).
4. Monitor the FTP Sensor volt-
age with the Honda PGM
Tester, or measure voltage
between bodY ground and
ECM/PCM connector termrnal
D15.
lntormittont t iluro, 3Ystem is OK
at this time. Check lot Poor con_
noctiona or loo3e wirat at C131
{loc.ted undor right 3id6 of d8hl,
CaOl llocatod rbov. under-dalh
fus6/relay boxl, C574 (C568lr
llocatod und6l accoss Pan6ll,C792 lfuel tank Preasulo aonlorl
end ECM/PCM.
ls there approx. 2 5 V?
Check for an oPen in the wire(SG2line):1. Turn the ignition switch OFF.
2. Reinstall the fuellill cap
3. Disconnect the fuel tank Pres-sure sensor 3P connector.
4. Turn the ignition switch ON (ll)
5. Measure voltage between the
fuel tank Pressure sensor 3P
connector terminals No. 1 and
No.2.
Ropair opon in the wira b€tw€sn
the fuel tank prasure sonlor and
ECM/PCM (Dl1).ls there aPProx. 5 V?
Check for an open in the wire(PTANK line):Measure voltage between the
fueltank Pressure sensor 3P con-
nector No. 3 terminal and No. 2
termrnal,
ls there approx. 5 V?
*: coupe
{To page 11-280)

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'99 - 0O modols except Dl5Y5 engine with M/T:
rFo45'::n":"tooIindicatesDiagnosticTroub|ecode(DTc)P0453:Ahighvo|tageprob|emintheFUelTankPressure
Wire side of temale terminals
FUEL TANKPRESSUNE SENSOR
SUB.HARNESS6P CONNECTOR {C574 (C568)}}
vcc2{YEL/BLUI
sG2IGRN/BLK)
Wire side of female terminals
PTANK{LT GRNI
(cont'd)
11-281
ECM/PCM CONNECTOR A {32P)
PTANK {LT GRN)
The MIL has been reported on.
DTC P0453 is stored.
Check the vacuum lines:
Check the vacuum lines ot the
fuel tank pressure sensor for mis-
routing, leakage, breakage and
clogging.
Are the vacuum lines OK?
Problem verilication:1. Do the ECM/PCM Reset Proce-
du re,2. Remove the fuel fill caP
3. Turn the ignition switch ON (ll).
4. Monitor the FTP Sensor volt'
age with the Honda PGM
Tester, or measure voltage
between body ground and
ECM/PCM connector terminalA.29.
lntermittent failuro. svstem b OK
at this time. Check for Poor con_
noctions or loo3€ wire3 at C131
{located under tight side of dash),
C4Ol {located above underdash
fuse/relay boxl, C57{ (C5681'
llocaled unde. access Panell,C792 {fuel tank Pressure sensorl
aod ECM/PCM.
ls there approx.2.5 V?
Ch€ck for an open in the wira
{SG2line):1. Turn the ignition switch OFF.
2. Reinstall the fuel fill caP
3. Remove the access Panellrom the floor.
4. Disconnect the fuel tank Pres-sure sensor sub-harness 6P
5. Turn the ignition switch ON (ll)
6, At the access Panelside, mea-
sure voltage between the fuel
tank pressure sensor sub_har-
ness 6P connector termlnals
No.5 and No.6.
Repair open in the wire between
the fueliank Pres3ure 3ensor and
ECM/PCM {Cl8).ls there approx.5 V?
Check lor an oPen in the wire
{PTANK linel:At the access Panel side, mea
sure voltage between the fuel
tank pressure sensor suo_harness
6P connector No. 2 terminal and
No. 6 terminal.
ls there approx. 5 V?
(To page 11.282)

IECM/PCM CONNECTOR
I
EVAP TWO WAYVALVE
Wire side oftemaleterminals
FUELTANK
(cont'd)
11-291
tn
VACUUMPUMP/GAUGE,0 - 30 in Hs
A973X - 041 -
xxxxx
(From page l1 290)
Check the EVAP two way valve:
See EVAP two way valve test (see
page 11-295).
Roplace the EVAP two way valve
Check the EVAP bypa$ solenoid
1. Remove the fuel tank (see
page 11-242J.2. LiIt up the fuel tank with a
transmission iack, and connect
the fuel tank pressure sensor
sub harness 6P connector to
the access panel side connec_
tor,3. Disconnect the vacuum hosefrom the EVAP two way valveand connect a vacuum PumPto the hose,4. Turn the ignition switch ON (ll)
5. Apply vacuum to the hose.
(To page 11 292)
(From page 11-290)
Check for an open in the wire
{PCS lin6):1. Turn the ignition switch OFF
2. Reconnect the 2P connector to
the EVAP purge control sole-
3. Turn the ignition switch ON {ll).4. Measu re voltage betweenEClr/PCM connector terminals
A6 and 82.
Ropair open in the wire betweenthe EVAP purge Gontrol solenoidvrlve and th6 ECM/PCM lA6lls there battery voltage?
Substitute a known-good ECM/
PCM rnd re{61. lf symptom/indi'
cation goes away, rePlace the
oiiginal ECM/PCM.

I
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(From page 11-292i
Chock the tollowing parts tolleakage to aimosphero, and
ropaii or replaco if necess6.y:. fuel fill cap. fuel tank. fuel v.por pipe. EVAP two way valve. EVAP bypas solonoid valve. tuel tank pre3suae sen3or. EVAP control cankter. EVAP control canisier veni3hut valve. EVAP purge conttol solenoid
. ORVR vent 3hut valve. ORVB vaoor recirculation valve. vacuum hoses tnd connactions
(From page 11 292)
Check toi an opon in the wiro(2wBS linol:1. Turn the ignition switch OFF.2. Reconnect the 2P connectorto the EVAP bypass solenoid
3. Turn the ignition switch ON (ll).
4. Measure voltage betweenECM/PCM connector terminals43 and 82.
Reprir opan in tho wire be(wean
th. EVAP byp.is solonoid valve
rnd rhe EcM/PcM (A31.ls there baftery voltage?
(cont'd)
11-293