1998 HONDA CIVIC Throttle

3.
5.
6.
1.
Fuel Cut-off Control
. During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at
speeds over the following rpm:. D16Y5 engine (M/T):850 rpm. D]6Y5 engine (CVT), D'16Y8 engine (USA M/T): 920 rpm
. Dl6Y8 engine (USA A,/I), D16Y7 engine (USA A,/T);910 rpm
. D16Y8 engine (Canada M/T), D16Y7 engine (canada): 990 rpm
' D16Y8 engine (Canada M/T): 1,000 rpm
. 816A2 engine: 970 rpm
. Fuel cut-off action also takes place when engine speed exceeds 6,900 rpm (D16Y5, D16Y7 engine; D'16Y8 engine:
7,000 rpm. 816A2 engine: 8.100 rpm), regardless of the position of the throttle valve, to protect the engine from
over-rewing. With '99 Dl6Y7 engine (A,/T) and '99 D16Y8 engine (A./T), the PCM cuts the fuel at engine speeds over
5,000 rpm when the vehicle is not moving.
IVC Compressor Clutch Relay
When the ECM/PCM receives a demand for cooling from the air conditioning system, it delays the compressor from
being energized, and enriches the mixture to assure smooth transition to the A,/C mode
Evaporative Emission (EVAP) Purge Control Solenoid Valve*'
When the engine coolant temperature is above 154'F (68'C). the ECM/PCM controls the EVAP purge control solenoid
valve which controls vacuum to the EVAP purge control canister.
Evaporative Emission (EVAP) Purge Control Solenoid Valve*a
When the engine coolant temperature above 154"F (68"C), intake air temperature above 32"F (0'C) and vehicle speed
above 0 mile (0 km/h) or [Ay'C compressor clutch on and intake air temperature above 160"F (41'C)], the ECM/PCM
controls the EVAP purge control solenoid valve which controls vacuum to the EVAP purge control canister.
Exhaust Gas Recirculation (EGR) Control Solenoid Valve*?
When EGR is required for control of oxides of nitrogen (NOx) emissions. the ECM controls the EGR control solenoid
valve which supplies regulated vacuum to the EGR valve
Alternator Control
The system controls the voltage generated at the alternator in accordance with the electrical load and driving mode,
which reduces the engine load to improve the fuel economy.
ECM/PCM Fail-safe/Back-up Functions
1. Fail safe Function
When an abnormality occurs in a signal from a sensor, the ECM/PCM ignores that signal and assumes a pre-pro-
grammed value for that sensor that allows the engine to continue to run.
2. Back-uD Function
When an abnormality occurs in the ECM/PCM itself, the fuel injectors are controlled by a back-up circuit independent
of the system in order to permit minimal driving.
3. Self diagnosis Function lMalfunction Indicator Lamp (MlL)l
When an abnormality occurs in a signal from a sensor, the ECM/PCM supplies ground for the lvllL and stores the DTC
in erasable memory. When the ignition is initially turned on, the ECM/PCM supplies ground for the MIL for two sec-
onds to check the MIL bulb condition.
4. Two Trip Detection Method
To prevent false indications, the Two Trip Detection Method is used for the HO2S, fuel metering-related. idle control
system, ECT sensor, EGR system and EVAP control system self-diagnostic functions. When an abnormality occurs,
the ECM/PCM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and
ON 0l) again, the ECM/PCM informs the driver by lighting the MlL. However, to ease troubleshooting, this function is
cancelled when you jump the service check connector. The MIL will then blink immediately when an abnormality
occurs,
5. Two (or Three) Driving Cycle Detection Method
A "Driving Cycle" consists ot starting the engine. beginning closed loop operation, and stopping the engine. lf misfir-
ing that increases emissions is detected during two consecutive driving cycles, or TWC deterioration is detected dur-
ing three consecutive driving cycles, the ECM/PCM turns the MIL on. However, to ease troubleshooting, this function
is cancelled when you jump the service check connector. The MIL will then blink immediately when an abnormality
occurs.
(cont'd)
1 1-1 05
.1.

PGM-FI System
Throttle Position ITP) Sensor ('96 - 98 Models,'99 - 00 D16Y5 engine with M/Tl
The scan tool indicates Diagnostic Trouble Code (DTC) P0122: A low voltage problem in the Throttle Position(TP) sensor circuit.
The TP Sensor is a potentiometer. lt is connected to the throttle valve shaft. As the throttle position changes, the throttleposition sensor varies the voltage signal to the ECM/PCM.
OUTPUT VOLTAGE IVI
1
2
1
0
s{i2(GRN/BLKI
THROTTLEOPENING
FULLTHROTTLE
TP SENSOR 3P CONNECTOR ICllOI
vocz(YEL/BLUI
Wire side ot femal6 terminals
ECM/PCM CONNECTOR D IT6PI
SG2 IGRN/ALKI
{To page l1-133)
Terminal side of male terminals
11-132
- Tho MIL h63 boon roportod on.- DTC m122 i. storcd.
Probl6m voritic€tion:1. Turn the ignition switch ON (ll).
2. Check the throttle positionwith the scan tool.
ls there approx. .49 V whenthe throttle is fully closed andapprox. 4.5 V when the throttleis lully op6ned?
Int..mittent tailura, rFiem ir OKat thit tima. Chock tor Door con-nections or loorc wires !t C110ITP lonrorl .nd ECM/FCM.
Ch6ck lor rn opon in the wire(VCC2linel:
1. Turn the ignition switch OFF.2. Disconnect ths TP sensor 3Pconnector.3. Turn the ignition switch ON lll).4, Measure voltage betweenthe TP sensor 3P conn€ctor ter-minals No. l and No.3.
ls there approx. 5 V?
Check for rn opcn in wire IVCC2line):Measure voltage between ECM/PCM conneclor terminals D10 and011.Chock for rn open or 3hort in TPlon30t:1. Turn the ignition switch OFF.2. At the s€nsor side, measureresistance between the TP sen-sor terminals No. 1 and No. 2with the throttle fully closed.
Roplir op€n in thg wiro batwcsnECM/PCM {DlO) rnd TP ren3or.ls there approx.5 V?
Substitut6 r known-good ECM/PCM and rach6ck. lf pro$ribodvohrge i! now avrilablc, replac€tho o.iginel €CM/FCM.
Wire side of female terminals

t
'P SENSOR 3P CONNECTOR
Terminal side of male terminals
ECi'/PCM CONNECTOR D {16PI
TPS IRED/Btx)
IGRN/BLK)
t-
hm
sG2
6Ittotl12
tlt5ta
Wire side ol lemale terminals
lDl6Y5 engine
f
TPS IR€O/BLKISG2 IGRN/BLKI
{From page l1'132}
ls there approx. 0.5 - 0.9 k0?
Check for an opsn or 3hort in thoTP sensor:Measure resislance between theTP sensor terminal No. 2 and
No. 3 with the throttle fully closod.
ls there approx.3.6 - 5.4 k0?
Chock lor an open in the ECM/
PCM ITPS lin6l:1. Reconnect the TP sensor 3P
connector.2. Turn the ignition switch ON {ll}.
3. Measure voltage between
ECM/PCM connector terminals
Dl and D11.
Substitut. r known-good ECM/
PCM and r.ch.ck. lf pt6crib.d
vohrga i. now !Y!il.blo, lcpl.co
tho odginal ECM/PCM.
ls there approx. 0.5 Vwhen the
throttle is fully closed and
approx. 4.5 Vwhen the throttleis fully opened?
Check tor . short in tha TCM:
1. Turn the ignition switch OFF.2. Disconnect the 22P connectorfrom the TCM.3. Turn the ignition switch ON (ll).
/t. Measure voltage between ECMconnector terminals D1 andD11.
ls there approx.0.5 V when the
throftle is tully closed andapprox. 4.5 V whon the throttleis fully opened?
Ropair rhort in the wir€ bdtwconECM/PCM (D11, TCM and TP i.n.
30r,
1 1-133

PGM-FI System
Throttle Position (TPl Sensor ('99 - 00 Models except D16Y5 engine with M/T)
lTO12Z _TI scan tool indicates Diaqnosttc Trouble Code (DTC) P0122: A low voltage problem in the Throttle position- { | r, sensoa crrcurl.
The TP Sensor is a potantiometer. lt is connected to the throttle valve shaft. As the throttle position changes, the throttleposition sensor varies the voltage signal to the ECM/PCM.
ERUSHHOI.DENOUTPUT VOLTAGE (VIBRUSH
BESIS?OF
TERi'I AL
5
4
3
2
1
o
INNERBUS}IINGTHROTTLEOPE II{G
FULLTHROTTLE
TP SENSOR 3P CONNECTOR {Cl1OI
sG2IGRN/8LKIvcc2(YEUBLUI
Wire side of temale terminals
ECM/PCM OONNECTOR C 131P)
Ch.Gk for rn opan or 3hort in TP36nlot:1. Turn the ignition switch OFF.2, At the sensor side, moasureresistance between the TPsensor 3P connector terminalsNo. 1 and No. 2 with th€ throt,tle fully closed.
(To page 11-135)
- Th. MIL har boon.6portcd on.- DTC P0122 b siored.
Problem verification:1. Start the engine, Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on.then turn the ignition switchOFF,2. Turn the ignition switch ON (ll).3. Check the throttle positionwith the scan tool.
ls there approx. .49 V whenthe throttle is fully clos€d andapprox, 4.5 V when the throttleis fully opened?
l||t rmittont failura, lyrtom b OKat thi! tima. Chock tor poor con-nactionr o. looao wires rt C110{TP 3.n!or} rnd ECM/PCM.
Check for an opan or 3hort in thowi.c (VCC2 linc):1. Turn the ignition switch OFF.2. Disconnect the TP sensor 3Pconnector,3. Turn the ignition switch ON (ll).4. Measure voltago betweenthe TP sensor 3P connector terminals No. 1 and No.3.
ls thero approx. 5 V?
Chccl tor .n opln in wiro IVCC2lin€l:Mgasure voltago between ECM/PCM connector terminals C18 and
R.prir opcn in the wiro bctw.enECM/PCM (C281 and TP 3€nror.ls there approx. 5 V?
Subrtituto r known-good ECM/PCM .nd rochcck. lf pro.c.ibedvoltaga i! now available, roplacotho origin.l ECM/PCM.
Wire side ol female terminrls
Terminal side of male terminals
11-134
L

L
I
(From page 11-134)
lsrhere approx.0.5 - 0.9 ko?
Chock for an open or 3hort in the
TP 3en30r:Measure resistance between the
TP sensor 3P connector terminalsNo. 2 and No. 3 with the throttle
tully closed.
ls there approx.4.5 k0?
Check for .n opon in th€ ECM/
PCM (TPS lino):1. Reconnect the TP sensor con-nector.2. Turn the ignition switch ON {ll).
3. Measure voltago between Cl8
terminal and C27 terminal on
the ECM/PCM conneclor.
Sub.lltut. . known-good ECM/
PcM lnd r.chock. ll pr6cribod
vohago b now lvallabla, aeplrca
tho originrl ECM/PCM,
ls there approx. 0.5 V when the
throttle is fully closed and
approx. 4.5 V when the throttle
is fully open€d?
Ropair ahort in th. wiro b€{weenECM/FCM lC18l .nd TP ..n.o].
TP SENSOR 3P CONNECTOR
Terminal side ol male terminals
ECM/PCM OONNCCTOR C (31PI
Wire side oI female terminals
.1,
11-135

PGM-FI System
Throttle Position (TP) Sensor (€6 - 98 Models, 39 - 00 D16Y5 engine with M/T)
The scan tool indicates Diagnostic Trouble Code (DTC) P0123: A high voltage problem in the Throttle Position(TP) sensor circuit.
TP SENSOR 3P CONNECTOR IC1lOI
sG2IGRN/BLKIvcc2{YEL/BLUI
Wire side of female terminals
ECM/PCM CONNECTOR D (16P)
SG2 (GRN/BLKI
Wire side of female terminals
1 1-136
The MIL has been reportod on.DTC P0123 is sto.ed.
Problom veritication:1. Turn the ignition switch ON {ll).2. Check the throttle positionwith the scan tool.
ls there approx. 10% when thethrottle is fully closed andapprox. 90o/o when the throttleis lully opened?
Intermittont tailuro, system is OKat thb timo, Check for ooor con-nociion3 or loos6 wiros at C110ffP s€nsor) and ECM/PCM.
Chgck to. an opan in the TP son-sot:1. Turn the ignition switch OFF.2. Disconnect the TP sensor 3Pconnector.3. Turn the ignition switch ON (ll).
4. At the harness side, measurevoltage between tho TP sensor3P connecter terminals No, 1and No.3.
ls there approx.5 V?
Ch.ck tor .n open in the wira(SG2 linel:Measure voltage between ECM/PCM connector terminals D10 andD11.
Repair op6n in the wire betwoenECM/PCM (D11) rnd TP s6nsor.ls there approx. 5 V?
Substitute a known-good ECM/PCM snd rech.ck. lf pra3cribed
voltago is now available, replscetho original ECM/PCM,

I
Throttle Position (TP) Sensor ('99 - 00 Models except D16Y5 engine with M/Tl
The scan tool indicates Diagnostic Trouble Code {DTC) P0123: A high voltage problem in the Throftle Position
{TP) sensor circuit.
TP SENSOR 3P CONNECTOR {C11OI
sG2{GRN/BLKIvoc2
{YEUBLU}
'l'Wire side of female term;nals
ECM/PCM CONNECTOR C (31PI
Wire side of femal€ terminals
(cont'd)
11-137
The MIL has been reported on
DTC P0123 is slored.
Problem verification:1. Start the engine. Hold the
engine at 3,000 rpm with no
load (in Park or neutral) until
the radiator fan comes on
then turn the ignition swatch
OFF,2. Turn the;gnition switch ON (ll).
3. Check the throttle Positionwith the scan tool.
lntormittenl tailure, 3ystom is OK
at this time. Check tor Poor con'
neqtions or loo3€ wires at C'110(TP sensorl tnd ECM/PCM.
ls there approx. 10% when the
throttle is fully closed and
approx. 90% when the throttleis fully opened?
Ch€ck for an open in the TP s6n-
soJ:1. Turn the ignition switch OFF.
2. Disconnect the TP sensor 3P
3. Turn the ignition switch ON (ll).
4. At the wire harness side, mea-
sure voltage between the TP
sensor 3P connector terminalsNo. 1 and No.3.
ls there approx. 5 V?
Check tor an open in the wire(SG2lino):
Measure voltage between ECM/
PCM connector C (31Pi terminals
C18 and C28.
Repair open in the wite betwe€nECM/PCM (Cl81and TP son.or.ls there approx. 5 V?
Substitute a known-good ECM/PCM and recheck. lf Pr$cribedvoltage is now aveilabl6. replacethe original ECM/PCM.

PGM-FI System
Throttle Position (TP) Sensor (cont'd)
- The MIL hss been.eported on.- DIC P1121 i. stored.
Problem vedficatiod:1. Turn the ignition switch ON (ll).
2. Check the throttle position
with the scan tool.
ls TP *% or higher indicatedwhen the throftle is tullyopenod?
Intermittent tailure, ryttem i! OKrtthistimo.
I Pl 121 | The sca n tool indicates Diag nostic Trouble Code (DTC) Pl 121: Throttle Position (TP) lower than expected.
*: 11.8 {D16Y5 enginei12.9 {016Y7 engine)12.2 (D16Y8 engine)13.7 (816A2 engine)
I P1122 I The scan tool indicates Diagnostic Trouble Code (DTC) P1122: Throttle Position (TP) higherthan expected.
*: 16.5 {Dl6Y5, Dl6Y8 engine}16.9 (D16Y7 engine)16.5 (81642 engine)
- The MIL ha3 be6n repoJted on.- DTC Pl122 i. llorod.
P.oblom v6dfication:1. Turn the ignition switch ON (ll).
2. Check the throttle position
with the scan tool.
ls TP'70 or l€ss indicated whenthe throttle is fully closed?Intormitt6ot frilu.o, aFtom b OKat thb timo.
1 1-138