1999 HONDA CIVIC engine coolant temperature sensor

ECM/PCM CONNECTOR D I16P)
Wire side ot female terminals
ECM/PCM CONNECTOR D l16P)NOTE: Standard battery voltage is 12 V
Te.minalnumb€r
Wirecolor
Terminaln!meDor.riptionSignal
RED/BLKTPS (THROTTLE POSITION
SENSOR}
Detects TP sensor signal.With throttle fully open: about 4.8 V
With throttle fully closedl about 0.5 V
REDA/VHTECT {ENGINE COOLANTTEMPERATURE SENSORDetects ECT sensor signalWith ignition switch ON{ll): about 0.1 - 4 8 v
(depending on engine coolant lempe ratu re)
3RED/G RNMAP {MANIFOLD ABSO'LUTE PRESSURE SENSOR}Detects MAP sensor signal.With ignition switch ON(ll): about 3 V
At idle: about 1.0 V
{depending on engine speed)
YEUREDVCCl (SENSOR VOLTAGE)Power source lor MAP sensor.With ignition switch ON (ll): about 5 v
With ignition switch OFF: 0 V
5GRNMHTBKSW {BRAKE SWITCHIDetects brake switch signalWith brake pedal released: 0 v
With brake pedal depressed: baftery voltage
6*?RED/BLUKS {KNOCK SENSOR}Detects KS signal.With engine knocking: Pulses
1
PHO2S (PRIMARY HEAT-ED OXYGEN SENSOR,SENSOR 1)
Detects Primary heated oxygen
sensor (sensor 1l signal
With throttle fullv opened from idle with
Iully warmod up engine: above 0.6 V
With throttle quickly closed: below 0.4 v
LABELDetects LABEL resistanceWith engine r!nning:about 0.3 - 4.9 V
8RED//ELIAT (INTAKE AIR TEM-PERATURE SENSOR)
Detects IAT sensor signal.With ignition switch ON (ll): about 0 1 -
4.8 V {depending on intake air temperature)
9*lWHT/BLKEGRL iEGR VALVE LIFT
SENSOR)
Detects EGR valve lift sensor signalAt idle without vacuum: about'1 2 V
With 27 kPa (2OO mmHg,8 in. Hg): about 4 3 V
10YEUBLUVCC2 (SENSOR VOLTAGE)Provides sensor voltage,With ignition switch ON(ll): about 5 V
With ignition switch OFF:0 V
11GRN/BLKSG2 (SENSOR GROUND}Sensor ground.Less than 1.0 V at alltimes
12G RN,4/1r'HTSG1 (SENSOR GROUND)Ground for MAP sensor.Less than 1.0 V at alltimes
GRN/BLK*1?SHO25G (SECONDARY
HEATED OXYGEN SEN'
SOR, SENSOR 2 GROUND)
Ground for secondary heated oxy-
gen sensor (sensor 2).
14WHT/REDSH02S (SECONDARY
HEATED OXYGEN SEN'soR, sENsoR 2)
Detects secondary heated oxygen
sensor (sensor 2) signal.With throftle fully opened lrom idle with
fully warmed up engine: above 0.6 V
With throttle quickly closed: below 0.4 V
15|3. *15LT GRNPTANK {FUEL TANK PRES.
SURE SENSOR)
Detects fueltank prgssure sensor'With fuelfill caD opened: about 2.5 V
16*1GRN/RED
EL (ELD)Detects ELD signal.With parking lights turned on at idle: about
2.5 - 3.5 VWith low beam headlights turned on at
idle: about 1.5 - 2.5 V
*1: USA model*2r A/T (D16Y7, D16Y8 engine)*3: CVT (D16Y5 engane)*4: A,/T and Dl6Y7 engine*5: Except A/T and D16Y7 engine*6: A"/T (D16Y8 engine)i7: CVT (Dl6Y5 engine) and Dl6Y8 engine*8: .96 D16Y8 engine (coupei,'97 D16Y8 engine
models, sedanr KL model),'98 016Y5 engine,
engine, '99 - 00 D16Y5 (M/T) engine
*9: D16Y5 engine*10: M/T (D16Y5 engine)*11: Except M/T (Dl6Y5 engine)* 12r D16Y5. D16YB engine*13: D16Y8 engine*14: Dl6W engine*15: '97 D16Y7 engine (coupe: KL model, sedan: KL lLX) model),'98D16Y7 engine:(coupe: all'98 D16Y8
(cont'd)
1 1-91

Diagnostic Trouble Code (DTCI Chart
connector is connecteda1: Dl6Y5 engine (CVT)*2: Except D16Y5 engine (M/T)*14:'97 model*15:'96 model*16: '98 model
(cont'd)
11-97
DTC
{MlL indication*lDelection liemProbable CausePage
Manifold Absolute
Pressure Circuit
Range/Performance Problem
. Vacuu m connection. MAP sensor11115
P0107 (3)
Manifold Absolute
Pressure Circuit
Low Input
Open or short in MAP sensor circuit
MAP sensor
ECMiPCM
TCM*1
11't1'l
P0108 (3)Manifold Absolute
Pressure Circuit
High Input
Open in MAP sensor circuit
MAP sensor
ECtvt/PCM
't 1 121
P0.111*14. *15 (10)
lntake Air Temperature
Circuit
Range/Performance Problem
. IAT sensor11-124
PO112 {10}
Intake Air
Temperature Circuit
Low Input
Short in IAT sensor circuit
IAT sensor
ECMiPCM
11-125
P0113 (10)lntake Air
Temperature Circuit
High Input
Open in IAT sensor circuit
IAT sensor
ECM/PCM
't1-126
P0116 (86)Engine Coolant
Temperature Circuit
Range/Performance Problem
. ECT sensor. Cooling system11-124
PO't't7 {6)
Engine Coolant
Temperature Circuit
Low Input
Short in ECT sensor circuit
ECT sensor
ECM/PCM
11-129
P0118 (6)Engine Coolant
Temperature Circuit
High lnput
Open in ECT sensor circuit
ECT sensor
ECM/PCM
11-130
?0122 t1l
Throttle Position
CircuitLow Input
Open or short in TP sensor circuit
TP sensorECM/PCM
TCM*1
11-132
P0123 (7)Throttle Position
Circuit
High Input
Open in TP sensor circuit
TP sensor
ECM/PClvl
11-136
P0131*' (1)
Primary Heated Oxygen Sensor
Circuit Low Voltage(Sensor 1)
Short in Primary HO2S (Sensorl ) circuit
Primary HO2S {Sensor 1)
Fuel supply system
ECM/PCM
1 1-139
P0132*' ('r)
Primary Heated Oxygen Sensor
Circuit High Voltage(Sensor 1)
Open in Primary HO2S {Sensor 1} circuit
Primary HO2S (Sensor 1)
ECM/PCM
1 1- 143
P0133*' (61)
Primary Heated Oxygen Sensor
Slow Response(Sensor 1)
. Primary HO2S (Sensorl). Exhaust system11-145
P0135*? (41)
Primary Heated Oxygen
Sensor Heater
Circuit Malfunction(Sensor 1)
. Open or short in Primary HO2S(Sensor 1) heater circuit. ECM11-151
*: The DTCS in parenthesis will be indicated by the blinking of the Malfunction Indicator Lamp (MlL) when the SCS service
! ta

PGM-FI System
System Description
CKP/TDC/CYP Sensor
MAP Sensor
IAT SensorTP SensorEGR Valve Lift Sensor*'Primary H02SSecondary HO2SVSSBARO SensorELD*'KS€Starter SignalALT FR SignalAir Conditioning SignalA/T Gear Position SignalBattery Voltage {lGN.1}Erake Switch SignalPSP Switch SignalFuel Tank Pressure Sensor*iVTEC Pressure Switch*5Clutch Switch Signal*6Countershaft Speed SensornBMainshaft Speed Sensorrs
-\
----t /
F;ilrr j"-----fi-tri-'r.;l
Fb"t."'i" d" c;;il
F,h"'c;;tr*".io";-l
@."r.l"sc;;ll
EaM/PcM B""k-p F"""till
r\
-:/
Fuel IniectorsPGM-Fl Main Belay {Fuel Pump)MILIAC Valve!y'C Compressor Clutch RelayRadiator Fan Relay*,Condenser Fan RelayALT*'lcMEVAP Purge Control Solenoid
Primary HO2S HeaterSecondary H02S HeaterEGR Control Solenoid Valve*rEGR valve*6EVAP Bypass Solenoid Valve*'EVAP Control Canister Vent Shut
VTEC Solenoid Valve*5DLCLock-up Control Solenoid Valve*aShift Control Solenoid Valve*3Linear Solenoid Valve*3
*1: Dl6Y5 engine*2: USA model*3: CW (D16Y5 ensine), D16Y8 engine and 81642 ensine*4: '96 D16Y8 engine lcoupe),'97 Dl6Y7 engine (coupe: KL model, sedan: KL (LX) model),'97 D16Y8 engine {coupe: all models, sedan: KLmodel),'98-all models,'99'all models,'00-all models+5: D16Y5, D16Y8,816A2 engine*6: M/T (D16Y5 enginei*7: CVT 1D'l6Y5 engine)+8: A/T (D16Y7, D16Y8 engine)*9: '96 D16Y5 engine,'96 D16Y7 engine,'96 Dl6Y8 engine (sedan),'97 D16Y5 engine,'97 Dl6Y7 engine (coupe: KA, KC models, sedan:KA, KC, KL (LX) models, hatchback: all models),'97 D16Y8 engine (sedan: KA, KC modelsi
PGM-FI Sy3lem
The PGM-Fl system on this model is a sequential multipon fuel injection system.
Fuel iniector Timing and Duration
The ECM/PCM contains memories for the basic discharge durations at various engine speeds and manifold air flow rates.
The basic discharge duration, after being read out from the memory. is further modified by signals sent from various sen-
sors to obtain the final discharge duration.
ldle Air Control
ldle Air Control Valve llAC Valve)
When the engine is cold. the A,/C compressor is on, the transmission is in gear, the brake pedal is depressed, the P/S load
is high, or the alternator is charging, the ECM/PCM controls current to the IAC Valve to maintain the correct idle speed.
lgnition Timing Control
. The ECM/PCM contains memories for basic ignition timing at various engine speeds and manifold air flow rates.
lgnition timing is also adjusted for engine coolant temperature.
. Aknockcontrol system was adopted which sets the ideal ignition timing for the octane rating ofthegasoline used.*3
Othgr Control Funqtions
1. Starting Control
When the engine is started, the ECM/PCM provides a rich mixture by increasing fuel injector duration.
2. Fuel Pump Control
. When the ignition switch is initially turned on, the ECM/PCM supplies ground to the PGM-Fl main relay that sup-plies current to the fuel pump for two seconds to pressurize the fuel system.. When the engine is running, the ECI\4PCM supplies ground to the PGM-FI majn relay that supplies current to the fuel
oumo.
. When the engine is not running and the ignition is on, the ECM/PCM cuts ground to the PGM-FI main relay which
cuts current to the fuel pump.
11-104
INPUTS
ENGINE CONTROL MODULE (ECMY
POWERTRAIN CONTROL MODULE (PCM) OUTPUTS

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
Engine Coolant Temperature (ECTI Sensor
The scan tool indicates Diagnostic Trouble code (DTC) P0116; A range/performance problem in the EngrneCoolant Temperature (ECT) Sensor circuit.
The ECT Sensor is a temperature dependant resistor (thermistor). The resistance of the thermistor decreases as the enginecoolant temperature increases as shown oetow.
RESISTANCE(ko)
NOTE: lf DTC P0117 and/or P01'18 are stored at the same time as DTCfor DTC P0116.
Possible Cause
. ECT sensor deterioration. Malfunction in the thermostat and cooling system
Troubleshooting Flowchart
-a 32 68 r0a la0l?6 2t2 2481'rr-20 o 20 ao o D r@ Il, r'c)
ENGINE COOLANT IEMPERATURE
P0116, troubleshoot those DTCS first. then recheck
11-128
THERMISTOR
- The MIL has bogn reported on.- DTC P0116 is stored.
Problem verification:1. Start the engine. Hotd theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on,then let it idle.2. With the scan tool, check the
Intermiftent lailure. system is OKai thi. time. Ch.ck the thc.mo-stat 6nd thc cooling system.
is 176 200'F {80 - 93'C)or0.0-0.TVindicated?
Check the thermostat and thecooling system. ll they als OK,raplace the ECT sensor.

|.
'f
fD;r.tt The scan tool indicates Diagnostic Trouble Code (DTC) P0117: A low voltage (high temperature) problem in the|jg Engine Coolant Temperature (ECTI sensor circuit.
ECT SENSOR 2P CONNECTOR (C122I
Wire side of female terminals
Substitute . lnown-good ECM/PCM .nd rocheck. It normrl ECT
is indic.ted, replaco the original
ECM/PCM,
*:'99 -Oo models except D16Y5 enginewith M/T
(cont'd)
11-129
The MIL has been ,eported on.DTC ml 1 7 is storod.
Problom vorification:1. Turn the ignition switch ON (ll).
2. Check the ECT with the scantool.
Intermittont failulo, sy3tom it OK
at thk tim., Chock for Poor oon-n.ctions or loo!. wiraa at C122IECT 3en orl and ECM/FCM.
ls 302"F (150"C) or higher {orH-Limit in Honda mode ofPGM Tester) or 0 V indicated?
Check toJ a short in the ECT s.n-5('t:1. Disconnect the ECT sensor 2P
connector.2. Check the ECT with the scanrool.
ls 302"F (150"C) or higher {orH-Limit in Hond6 mode ofPGM Testerl or 0 V indicated?
Check for a 3hort in tho wiro
IECT linel:1. Turn the ignition switch OFF.2. Disconnect the ECM/PCM con-nector D (16P) (C {31P))*.3. Check for continuity betweenthe ECT sensor 2P conneclor ter-minalNo, 1 and bodyground.
B.gair short in the wiro bltweenECM/PCM (D2 (C261'l .nd ECT
.1,

PGM-FI System
Engine Coolant Temperature (ECT) Sensor
('96 - 98 Models,'99 - 00 D16YS engane with M/T) (cont'd)
The sc€n tool indicates Diagnostic Trouble Code (DTC) P0118; A high voltage (low temperature) problem in theEngine Coolant Temperature (ECT) sensor circuit.
ECt SENSOR 2P CONNECTOR {C1221
ECTIRED/WHTI
JUMPER WIRE
sG2(GRN/BLK)
Wire side of female terminals
ECM/PCM CONNECTOR D Il6PI
sG2 tGRN/81r0
Wire side of Iemale terminals
- Tho MIL ha3 bcen r€oorted on.- OTC m118 b stored.
Problom vorificttion:1. Turn the ignition switch ON (ll).
2. Check the ECT with the scantool.
Intcrmitt.nt failui.. rydom is OKat thir timc. Chack for Door con-naction! or loor! wiaar at C122IECT ..n.orl .nd ECM/rcM,
ls -4"F (-20'C) or less (or L-Limitin Honda mode ol PGM Tester) or5 V indicated?
Chsck lor sn open in thc ECT 3an-soa:1. Disconnect the ECT sensor2P connector.z. Lonnecr rne ELt sensor zFconnector terminals No. 1 andNo.2 with a jumper wire.3. Check the ECT with the scantool.
ls -4'F (-20'C) or loss (or L-Limitin Honda mode ol PGM Testerlor5 V indicated?
Chack for an opon in the wire.{ECT, SG2lin..l:1. Turn the ignition switch OFF.2. Connect ECM/PCM connectorterminals D2 and D11 with ajump€rwire.
3. Turn the ignition switch ON (ll).4. Check the ECT with the scantool.
ls -4'F 1-20'Clor less (o. L-Limitin Honda mode ol PGM Tester)or5 V indicated?
Reprir oprn in tha wirar bstwoonCCM/PCM IDZ Dl1) .nd EGT rcn-aor.
Sub3titut. s known-good ECM/FCM and r.chcck, It normel ECTi! indicatod, roplaco tho origin.lECM/PCM.
JUMPER WIRE
1 1-130

PGM-FI System
t
I
Engine Coolant Temperature (ECT) Sensor
('99 - 00 Models except Dl6Y5 engine with M/Tl
The scan tool indicates Diagnostic Trouble Code (DTC) P0118: A high voltage (low temperature) problem in the
Engine Coolant Temperature (ECT) sensor circuit.
ECT SENSOR 2P CONNECTOR {C122)
ECT(RED/Wr{T)
JUMPER IVIRE
sG2{GRN/BLK)
wire side of female terminals
ECM/PCM CONNECTOB C 131PI
The MIL has been reported on,
oTC P0118 is stored.
Problem verilication:1. Turn the ignition switch ON (ll).
2. Check the ECT with the scan
tool.
lntormittent failuro, systom is OK
at thb timo. Check lor poor con'nections or 10036 wiraa at C122
{ECT ssnsorl and ECM/rcM.
ls -4'F (-20"C) or less lor L-Limit
in Honda mode o{ PGM Tester) or
5 V indicated?
Check for an open in the Efi sen'
sori1. Disconnect the ECT sensor 2P
connector,2. Connect the ECT sensor 2P
connector terminals No, 1 andNo. 2 with a jumper wire.3. Check the ECT with the scantool.
ls -4"F 1-20"C) or less (or L-Limit
in Honda mode of PGM Tester) or
5 V indicated?
Check for sn open in the wires
IECT. SG2 linesl:1. Turn the ignition switch OFF.2. Connect ECM/PCM connectorterminals C18 and C26 with ajumper wire.3. Turn the ignition switch ON (ll).
4. Check the ECT with lhe scantooi.
Rspair opon in th6 wiros bstwoon
ECM/PCM (Cl8, C26l and ECT
3ensot.
ls -4'F {-20"C) or less (or L-Limit
in Honda mode of PGN4 Tester) or
5 V indicated?
Substitute 6 known-good ECM/PCM and recheck. l{ no.mal EcT
is indicatod, .eplace the originalECM/PCM.
JUMPER WIRE
Wire side of female terminals
11-131