1999 HONDA CIVIC system description

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lTo420l Th" """n toot indicates Diagnostic Troubte code (DTc) p0420: catatyst sysrem efficiency below threshold.
Description
This system evaluates the catalyst's capacity by means of the Ho2s {Primary and secondary) output during stable driving
conditions. ll deterioration has been detected during two consecutive driving cycles. the MIL comes on and DTC P0420 will
be stored.
NOTE: lf some of the DTCS tisted below are stored at the same time as DTC P0420, troubleshoot those DTCS first. then
recheck for DTC P0420
P0137, P0138: Secondary HO2S (Sensor 2)
Po14'1:Secondary H02S {Sensor 2) Heater
Possibl€ Cause
. TWC Deterioration
. Exhaust system leakage
Troubleshooting Flowchart
I
The MIL has been reported on.
DTC P0420 is stored
Problem verilication:1. Do the ECM/PCM Reset Proce
dure.2. Start the engine Hold the
engine at 3,000 rpm wath no
load {in Park or neutral) until
the radiator fan comes on.
3. Connect the SCS service con
4. Test drive 40 - 55 mph for
approx, two minutes Then
decelerate for at least 3 sec_
onds with the throttle com'pletely closed- Then reduce
the vehicle speed to 35 mph,
and try to hold it until the
readiness code comes on
Intermittent Iailure, system is OK
at this time.ls DTC P0420 indicated?
Check the TWC {see section 9l
lf necessary, replace the TwC

1\
Evaporative Emission (EVAPI Controls
Description
The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The
system consists of the foliowing components:
A. Evaporative Emission (EVAP) Control Canisto]
An EVAP control canister is used for the temporary storage of fuel vapor until the fuel vapor can be purged from the
EVAP control canister into the engine and burned.
B. Vapor Purge Control System
EVAP control canister purging is accomplished by drawing fresh air through the EVAP control canister and into a port
on the intake manifold. The purging vacuum is controlled by the EVAP purge control solenoid valve.
I'96 D16Y5 engine,'96 Dl6Y7 engine,'96 D16Y8
engine (sedan),'97 D16Y5 engine,'97 D16Y7
engine (couper KA, KC models, sedan: KA, Kc'
KL iDX) models, hatchback: all models), '97
D 16Y8 engine (sedan: KA, KC models)l
I'96 D16Y8 engine (coupe),'97 D16Y7 engine
(coupe: KL model, sedan: KL (LX) model)"97
D16Y8 engine (coupe: all models, sedan: KL model)'98-all models,'99-all models,'00-all modelsl
I
c.
D.
or
l'lc COMPRESSOR CLUTCH ON
and
INTAKE AIR TEMPERATURE ABOVE 160"F (41'C)
Fuel Tank Vapor Control System
When fuel vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and
regulates the flow of fuel vapor to the EVAP control canister.
Onboard Refueling Vapor Recovery (ORVRI System {'99 - 00 models}
During refueling. the oRVR {onboard Refueling Vapor Recovery) vent shut valve opens with the pressure in the fuel
tank. and feeds the fuel vapor to the EVAP control canister.
t(cont'd)
11-267
EVAP PURGE CONTROL SOLENOID VALVE DUTY CON-
TROLLED AFTER STARTING ENGINE
ENGINE COOLANT TEMPERATURE ABOVE 154'F {68"C)
INTAKE AIR TEMPERATURE ABOVE 32'F (O'C)
and
VEHICLE SPEED ABOVE O MILE (O KM/h}
ENGINE COOLANT TEMPERATURE ABOVE 154'F (68'C)

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,96 D16Y5 engine,,96 D16r,gngino,,96 Dt6Y8 engine {3edan)' 37 D16Y5 engino..97 D16r, engine {coupe: KA, Kc mod-
els. sedan: KA, KC, KL {DX} models. hatchback: all modols}''97 Dl6Y8 ongine (s€dan: KA' KC mod€lsl:
The scan tool indicates Diagnostic Trouble code (DTC) P0441: Evaporative Emission (EVAP) control system
insufficient purge flow.
Description
By monitoring the purge line vacuum with the MAP sensor, the ECM/PCM can detect insufficient EVAP control system
purge flow.
Possible Cau3e
. EVAP Purge Control Solenoid Valve
. EVAP Purge Control Solenoid Valve Circuit
. EVAP Control Canister
. Vacuum Lines
. ECM/PCM
Troubl93hooting Flowchart
Wire side of femaleterminals
EVAP PURGE CONTROI-sottNotD vALvE 2P
CoNNECTOR (Cl1al
r-+-r
I'l'l
lG-ro.*l'rr"r
O)
Y
(cont'd)
11-271
- The MIL has bsGn.eportad on.- DTC milal k rtored.
Pioblem vsrificJtion:1. Start the engine. Hold the
engine at 3,000 rPm with no
load {in Park or noutral) until
the radiator fan comes on.
2. Do the ECM/PCM Reset Proce'
dure,3. Connect the SCS service con-
nector.4. Test-drive under following con-
ditions on the road- Without any electrical load- A/T in E or E Position(M/T in 3rd-sth gear)- Engine sPeed betweon
1,200 - 2.400 rpm.- Decelerate {rom 50 mph (80
knl/h)to 15 mph (24 km/h)lntormittont lailuro, sFtorn b OK
at thi. timo. Ch€ck tor Poor con'
ncction3 or looac wir.3 at C144
{EVAP purgo control tolonoid
vrtv.l .nd ECir/FCttl.
ls DTC P0441 indicatod?
Ch.ck fo. !n op€n in the wiro l|(illinel:1. Turn the ignition switch OFF.
2. Disconnect the EVAP Purgecontrol solenoid valve 2P con_
neclor,3. Turn the ignition switch ON (ll)
4. Measur€ voltage between bodyground and the EVAP Purgecontrol solenoid valve 2P con-
nector terminal No 1.
Rop.ir opor in tho wir6 b€two€n
the EVAP purgo codtiol tolonoid
v.lvo rnd tho No 15 ALIERNA'
TOR SP SENSOR 17.5 A)lu.o.
{To page 11-272)

Automatic Transmission
Special Tools ......... .....'."".'-.-.' 14'2
Description .,....................-...... 14-3
power Flow ......,................. 14"6
Elestronic Control System .... . ................'..'.'.. 14-13
Hvdraulic Control .....'......" 1'l-19
Hydraulic F|ow...... .'.'.".'....11-21
Lock-up System '............ ... t/t'33
Electrical System
Component Locations....,.............'......'.............'.,. 14'39
PCM Circuit Diagram
lA/T Control Syst€m: '96 - 98 Models) .........'.. 1/t-40
PCM Tarminal Volt8ge/Measuring Condhions
{'96 - 98 ModeblA/T Control System ............
PCM Circuit Disgram(A/T Conlrol System: '99 - 00 Modsls) '..........' 14-44
PCM Terminal Voltage/Measuring Conditions('99 - 00 Models)A/T Control System ...
Troubleshooting Proceduros ....
Symptom-to-ComPonent Chari
Efectricaf SFiem - '96 - 98 Models '..-.-..."'.'..11-52
Eloqtrical System -'99 - 00 Modols ... .........". 1+54
EleclricatTroubl$hooting ('96 - 98 Models)
Valve Body
Repair .................... ........'.... 14-139
Valve
Assembly
ATF Pump
1,1-1i10
Inspection ...........'.......... 14-141
Main Valvs Body
Disass€mbf y/lnspoction/R.sssembly .'.'.'.'.. -. -. 1 1-1 12
Secondsry Valve BodY
Disa$embfy/lnspoction/Rsassembly ......'.'.'.'. 11-111
Regulator Valve Body
Disa$embly/lnspoction/Rea3sembly ..........'... 14-1{5
Servo Body
Disassombly/lnsp€ction/Reassembly .".'........ 14-146
Lock-up Valv6 Body
Dis$s.mbf y/ln3poction/Rea$embly .'.. -. -..'.'.' 1 1-1 17
Mainsh!ft
Dkassembly/lnep€ction Reassembly ..'...'........ 14'148
Inspoction .............'..........'. l it-149
Countsrshaft
Disa$embly/lnspeqtion/Rea3sembly .......'...'.. 1a-l51
Dba$ombly/Re$s.mblY11-152
til-46
I rl-48
Troubleshooting Flowcharts
Electrical Troubleshooting ('9!t - 00 Models)
Troublsshooting Flowchart3
Lock-up Control Solenoid vslvo A/B AssemblY
RePlacoment
Shift Cont.ol Solenoid Valve A/B A3sembly
Inspestion
Ona-way Clutch
Disassembh/lrupoction/Rca$embly .. "'........ l4-155
Clutch
lllustlttcd Ind.x {A48A, B4RA Transmlssion) ..' 14-156
tustr.tod Index (MrnA Transmi$ionl ............ til-158
...................... 14-153
L
14-56
1+81'
14-105
1+105
Replacoment ......
Mainshaft/Countorshaft Spo€d Sonsors
Replacemsnt ......'."'........... lit'108
Hydraulic System
Symptom-to-Componeni Chart
Hydraulic Sydemr+109
t4-113
1+116
11-117
Rea$emblY
14-106 Difforrr ial
llhdraied Index........ t4-156
B.ckhrh ln3poction. 14-167
Boaring Roplacemont..-..........11-167
..... 14-108 Diftrrsniial Carrior Repl8cemeni .'.-.............'...' lil-168
Oil Sall Romovalt4-t 59
Oil Soal ln3tallstion/Sidc Clearance'......'.....'... 1'l'169
Torqua Convertcr Housing Boarings
Mlin3haft Besring/Oil Scal Roplac.ment ."..'.. lil-172
Counio6hatt Betring R.plscem.nt ..'...... ....... 14-173
Test.....,......14-106
14-107
14-160
11-162
11-171
11-175
Replacement
Test .....,.,..........
Road Te3t
Linear Solenoid AsssmblY
Stall Speed
lllustrated Indax
Transmission/End Cover'. ....
Transmission Hou3ing,.............'.'......'....""..-.-.. 11-128
Torque Conve.ter Housing/Valvo Body ........... 14-130
End Cover
14-itB Park Stop
1+119 In3pection/Adiustmsnt...'......'.'............'...."""'14-175
Transmbgion
Reassombly
11-122 Torquo Convertet/Drivr Plsie ............'.'............'.. . l4-182
Transmission
11.726 Inrtallation
Tranlmission Housing Boarings
Msinsh.ft /CounteEhaft Bearings
B!pltcomgnt
Rcvo.3s ldlor Gear
lnrtallation
Cooler Flushing ..
Shift Cabls
Test
Fluid Level
Checkin9 .........."..'.'.....
Changing
Pressure Testing
Transmission
Transmission
Rgmoval ..
lil-176
.'..........'.'.'..... 1'l-183
.... lil-187
11-132Adiustmont
RemovaUlnttallation1,1-190
lit-191Transmisgion Housing
Removal ... '.'...... ......'..... 14-l3il
Tolque Convgrter Housing/valvs Body
Rsmoval .........,...... ............. 14-136
Valve CaDs
Description .......'................. t 4'138
Shift lndicator Panel
Adiu3tmant ..'.................. 14-192
ATF Coolor Hoses
Connection ..,............,.,....... l'l-192
Shift Lever .,........

Description
Electronic Control System (cont'd)
Shift Control
The PCM instantaneously determines which gear should be selected by various signals sent from sensors, and actuatesthe shift control solenoid valves A and B to control shifting. Also. a Grade Logic Control System has been adopted to con-trol shifting in E position while the vehicle is ascending or descending a slope, or reducing speed.
PoshionGearShift Control Solenoid
Vslve A
Shift Control Solenoid
Valve B
8,tr
1stOFFON
2ndONON
3rdONOFF
E4thOFFOFF
tr2ndONON
E-ReverseONOFF
*See page 14-31 for reverse inhibitor control description.
Lock-up Control
From sensor input signals, the PCM determines whether to turn the lock-up ON or OFF, and activates lock-up controlsolenoid valve A and/or B accordingly. The combination of driving signals to lock-up control solenoid valves A and B andthe linear solenoid pressure is shown in the table below.
Lock-up ConditionsLock-up Control
Solenoid Valvo A
Lock-up Control
Solenoid Valve B
Linoar Solonoid
Prggguro
Lock-up OFFOFFOFFHigh
Lock-up, HalfONDuty operation
OFF * ONLow
Lock-up, FullONONHigh
LOCK-Up
during decelerationONDuty operation
OFF - ON
a
14-14

Description
Electronic Control System {cont'dl
Ascending Control
When the PCM determines that the vehicle is climbing a hill in E position, the system oxtends the sngagement area of2nd gear and 3rd gear to prevent ths transmission from fr€quently shifting between 2nd and 3rd gears, and between 3rdand 4th gears, so the vehicle can run smooth and have more power when needed. There are two ascending modes withdifferent 3rd gear driving areas according to the magnitude of a gradient stored in the pCM.
NOTE:
. The PCM memory contains shift schedules between 2nd and 3rd gears, and between 3rd and 4th gears that enable thePCM's fuzzy logic to automatically select the most suitable gear according to the magnitude of a gradient. Fuzzy logic is a form of artificial intelligence that lets computers respond to changing conditions much like a humanmind would,
Dssconding Control
When the PCM determines that the vehicle is going down a hilt in E position, the shift-up speed from 3rd to 4th gearwhen th€ throftle is closed becomes faster than the set speed for flat road driving to widen the 3rd gear driving area.This, in combination with engine braking from the deceleration lock-up, achieves smooth driving when the vehicle isdescending. There are two descending modes with different downshift (4 - 3) schedules according to the magnitude of agradient stored in the PCM. When the vehicle is in 4th gear, and you are decelerating on a gradual hill, or when you areapplying the brakes on a steep hill, the transmission will downshift to 3rd gear. When you accel6rate, the transmission willthen return to 4th gear.
ASCENDING MODEDESCENDING MODE
4TH SHIFTING
L.
F
CHARACTERISIICSCONTROL AREA
ff.1"11", vehicr. 3pe€dff;Tlr., vohicre speed
GRADUAL ASCENOINGCONTROL AREA
Docel6ration Control
When the vehicle goes around a corner. and needs to first decelerate and then accelerate. the rcM sets the data for decelerationcontrol to reduce the number of times the transmission shifts. When the vehicle is decelerating from speeds above 26 mph(41 km/h), the rcM shifts the transmission from 4th to 2nd earlier than normal to cope with upcoming acceleration.
14-16

Description
Electronic Control System (cont'dl
Circuit Diagram and Terminal Locations -'99 - O0 Models
GNTONSWICH,,--b. rcj
LI
LOCK.UPCONIFOLSOLEI\Q D VALVE A
LOCK UP CON'IROLSOLENODVALVEB
SH FI CONTROL
SHIFTCONTFOLSOLENOIDVALVEE
L NEAF SOLEIOIO
PG2
IGP2
v3u
vcc2
sc2
6NII ON SWICH
14-18

Description
Hydraulic Control (cont'dl
Regulator Valve
The regulator valve maintains a constant hydraulic pressure from the ATF pump to the hydraulic control system, whitealso furnishing fluid to the lubricating system and torque converter. The fluid from the ATF pump flows through B and 8,.The regulator valve has a valve orifice. The fluid entering from B flows through the orifice to the A cavity. This pressure ofthe A cavity pushes the regulator valve to the right side, and this movement of the regulator valve uncovers the fluid portto the torque converter and the relief valve. The fluid flows out to the torque converter, and the relief valve and regulatorvalve moves to the left side. According to the level of the hydraulic pressure through B, the position of the regutator vatvechanges and the amount of the fluid from B' through D and c also changes. This operation is continued. maantaining theline pressure,
NOTE: When used. "|eft" or "right" indicates direction on the illustration betow.
ENGINE NOT RUNNING
TOROUE CONVERTER
ENGINE RUNNING
To TOROUE CONVERTER Lubrication
Stator Roaction Hydraulic Prossur6 Control
Hydraulic pressure increases according to torque, are performed by the regulator valve using the stator torque reaction.The stator shaft is splined with the stator in the torque converter, and its arm end contacts the regulator sprang cap. whenthe vehicle is accelerating or climbing (Torque Convert€r Range), the stator torque reaction acts on the stator shaft, andthe stator arm pushes the regulator spring cap in the direction of the arrow in proponion to the reaction. Jne stator reac-tion spring compresses, and th€ reoulator valve moves to increase the line pressure which is regulated by the regulatorvalve. The line pressure reaches its maximum when the stator torque reaction reaches its maximum.
STATOR SHAFT ARM
REGULATOR VALVE
14-22
STATORATOR SHAFT ARM
SPRING CAP