1996 HONDA CIVIC Engine control

Electronic Control System ('96 - 98 Modelsl
The electronic control system consists of the Transmission control Module (TcM), sensors, three linear solenoids, and an
inhibitor solenoid. Shifting is electronically controlled under all conditions
The TCIM is located below the dashboard, behind the kick panel on the driver's side'
The TcN4 controls the transmission to reduce engine speed and retain the engine's cooling efficiency when the vehicle is
driven with Iull throttle acceleration
lf the vehicle is continuously driven at full throttle acceleration, the TCM regulates the pulley hydraulic pressure to
increase the pulley ratio, which, as the result. reduces the engine speed and retains the designed cooling efficiency After
the vehicle has been driven at a lower engine speed for a while, the TCM increases the pulley ratio to the original ratio.
For smooth starting in the E position, the TcM sends a signal to the EcM to cut off the rvc clutch {if the A!/c is on) and
increases the engine speed to 900 rpm when the transmission is shifted to the E position'
The start clutch functions to make smooth starting possible. To let the start clutch function properly. the TCM regulates
the start clutch hydraulic pressure based on the entine's negative pressure memorized in the E position'
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S*ond.ry G..r Sh:ft
(cont'd)
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Electronic Gontrol System ('99 - 00 Modelsl
The electronic controt system conststs of a Powertrain control Module (PCM). sensors, three linear solenoids and an
inhibitor solenoid. shifting is electronically controlled under all conditions A Grade Logic control system to control shift-
ing in E position while the vehicle is ascending or descending a slope'
fn"pCVirlocatedbelowthedashboard,underthekickpanelonthepassenger'sside'
The pCM controls the transmassion to reduce engine speed and retain the engine's cooling efficiency when the vehicle is
driven with full throftle acceleration
lf the vehicle is continuously driven at lull throttle acceleration, the PCM regulates the pulley hydraulic pressure to
increase the pulley ratio which. as the result, reduces the engine speed and retains the designed cooling efficiency After
the vehicle has been driven at a lower engine speed for a while, the PCM increases the pulley ratio to the original ratio'
i"i ".nl",rr starting in the E position, the PcM cuts off the ,Vc clutch (if the A/c is on) and increases the engine speed to
900 rpm when the transmission is shifted to the E position'
The start clutch functions to make smooth starting possible. To let the start clutch function properly, the PcM regulates
the start clutch hydraulic pressure based on the engine's negative pressure memorized in the E position'
FCM
s*o.d.ry G..t Sh.h
(cont'd)
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Description
Electronic Control System ('99 - 00 Modelsl (cont'dl
Grade Logic Control System
How it works:
The PcM compares actual driving conditions with memorized driving conditions. based on the input from the vehiclespeed sensor, the throttle position sensor, the manifold absolute pressure sensor, the engine coolant temperature sensor,the brake switch signal, and the shift lever position signal, to control shifting while the vehicle is ascending or descendinga slope.
Ascending Control
When the PCM determines that the vehicle is climbing a hill in E position, the system selects the most suitable shiftschedule (pulley ratio) according to the magnitude of a gradient. so the vehicle can run smooth and have more powerwhen needed. There are three ascending modes with different shift schedules according to the magnitude ot a gradient inthe PCM.
Descending Control
when the PCM determines that the vehicle is going down a hill in E position. the system selects the most suitable shiftschedule (pulley ratio) according to the magnitude of a gradient. This, in combinstion with engine braking, achievessmooth driving when the vehicle is descending, There are three descending modes with different shift schedules accord-ing to the magnitude of a gradient in the PCM.
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Description
Hydraulic Control
The hydraulic control system is controlled by the ATF pump. the valves, and the solenoids. The ATF pump is driven by theinput shaft. The ATF pump and the input shaft are linked by the ATF pump drive chain and the sprockets, The inhibitorsolenoid valve and the linear solenoids. which are located on their valve body, are controlled by the TCM or pcM. Fluidfrom the ATF pump flows through the PH regulator valve to maintain specified pressure to the drive pulley, the driven pul-ley, and the manual valve,
The lower valve body assembly includes the main valve body, the PL regulator valve body, the shift valve body, the startclutch control valve body, and the secondary valve bodv.
Main Valve Eody
The main valve body contains the pH control valve, the rubrication valve, and the pitot regulator valve.
PH Control Valve
The PH control valve supplies PH control pressure (PHCI in accordance with the pH-pL control pressure (HLc), and sup-plies PH control pressure to the PH regulator valve, which also regulatss PH pressure. At kick-down, it increases pHcontrol pressure which increases the high (PH) pressure. This shortens the shift speed by releasing the reverse inhibitorpressure (Rl)from the inhibitor solenoid valve.
Lubrication Valve
The lubrication valve controls the lubrication pressure to each shaft and maintains lubrication pressure. When rne pres-sure is too high, the spring is compressed. This moves the lubrication valve and opens the fluid leak passage.
Pitot Regulalor Valv6
The pitot regulator valve controls the start clutch pressure (SC) in accordance with the engine speed, when the electron-ic control system is faulw.
MAIN VAIVEBODY
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Description
Hydraulic Control {cont'dl
PL Regulator Valve Body
The PL regulator valve body contains the PL regulator valve and the PH-PL control valve. which is joined wirh the pH-pL
control linear solenoid. The inhibitor solenoid is bolted on the pL regulator valve body.
. PL Regulator Valve
The PL regulator valve supplies low p.essure (pL) to the pulley to eliminate steel belt slippage.The PL pressure is controlled by the pH-pL control pressure (HLC).
. PH-PL Control Valve
The PH-PL control valve controls the PL regulator valve according to engine torque. The PH-PL control valve suooliesPH-PL control pressure (HLC) to the PH control valve to regulate PH pressure higher than pL pressure. The pH-pL con-trol valve is controlled by the PH-PL control linear solenoid. which is controlled by the TcM or pcM,
. Inhibitor Solenoid
The inhibitor solenoid controls the reverse inhibitor valve by turning on and off. Also, the inhibitor solenoad controls pH
control pressure (PHC) by applying reverse inhibitor pressure (Rl) to the PH control valve. The inhibitor solenoid is con-trolled by the TCM or Pclvl.
Start Clutch Control Valv€ Body
The start clutch control valve body contains the start clutch control valve. Both are joined to the stan clutch control linearsolenoid.
. Start Clutch Control Valve
The start clutch control valve controls start clutch engagement according to the throttle opening. The start clutch con,trol valve is controlled by the stan clutch control linear solenoid, which is controlled bv the TCM o. pCM.
START CLUTCH CONTROLvAt-vE
LOWER VALVE BODYASSEMBI-Y
PH.PL CONTROLLINEAR SOLENOID
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E Position
Astheengineturns.theATFpumpa|sostartstooperate.F|uidfromtheATFpumpf|owstothePHregu|atorva|veandthe
c|Utchreducingva|ve.ThePHregu|atorva|veregu|ateshighpressure(PH).andsendittotheshiftVa|veandthePLregU'
latorvalve.Thehighpressure(PH)flowstothemovablefaceofthedrivenpulleyviatheshiftvalve'andturnsintolow
pressure(PL)atthePLregu|atorva|ve.Thelowpressure(PL}f|owstothemovab|e'aceofthedrivepu||eYviatheshift
valve. At this time, the pulley ratio remarns low'
Thehighpressure(px)uecomesttrectutchreducingpressure(CR)atthec|utchreducingva|Ve.Thec|utchreducingpres.
sure (CR) flows to the start clutch cont'oi uatt". tn"lt"n'al valve' the PH-PL control valve' and the shift control valve' and
is intercepted bY those valves
Under this condition, hydraulac pressure is not applied to the clutches and reverse brake'
(cont'd)
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Component Locations
36 - 98 Models
BRAKE SWITCH
DRIVEN PULLEYSPEED SENSOR
INHIBITOR SOLENOID
ENGINE CONTROLMODULE IECMI
SECONDARY GEAR SHAFTSPEEO SENSOR
AUTOMATIC TRANSAXLE (A/T}GEAR POSITION SWITCI{
MANIFOLD ABSOLUTE
VEHICLE SPEEO SENSOR{vss}
IMAPI SENSOR
THROTTI.I POSITION {TPISENSOR
PH.PL CONTROLLINEAR SOLENOID
/i/ i,' / ,','4
,i/:1
t"--.---.- i,,
-_,-:-_a.--:
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START CLUTCH CONTROLLINEAR SOLENOIDPULLEY
SHIFT CONTROLLINEAR SOLENOTD
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h
SPEED SENSOR

TCM Terminal Voltage/Measuring Gonditions
('96 - 98 Modelsl
TCM Terminal Loc.tions
TCM-A l25P) Connecto.
TCM CONNECTOR A (26P}
TCM-B (22P) Connectot
2418910111213
1115161720232526
Terminal NumbetSignalDsscriptionMoasuring Conditions/Torminsl Vohrgo
A1SC LS_Stan clutch control linear solenoidpower supply negative electrodeEngine idling, E position:Approx. 0.4 VHLC LS-PH-PL control linear solenoid Dowersupply negative electrodeEngine idling, E position:Approx. 0.7 V
Shift control linear solenoid oowersupply negative electrodeEngine idling, E position:Approx. 0.8 V
A4LG1Ground
NEEngine speed signal inputWith engine running: Pulsing signalA6Not used
A7ATP LA/f gear position switch El positionsignal inputInEposition:OVIn other than El position: Approx. 1O VA8ATP Sly'T gear position switch E positionsignal inputIn lg position: 0 VIn other than E position: Approx. 10 VA9ATP DA{/T gear position switch E positionsignal inputIn lll position: 0 VIn other than E position: Approx. 10 VAr0ATP NPA,/T gear position switch E or Eposition signals inputInEorEposition:oVIn otherthan E orE position: Approx. 1O VA11ATP RA,/T gear position switch E positionsignal inputIn lE position: 0 VIn other than E position: Approx. 1O VA.12tGlPower supply systemWith ignition switch ON (ll): Banery voltsgeWith ignition switch OFF: 0 VA13PG1Ground
414Start clutch control linea. solenoidpower supply positive electrodeEngine idling, E position:Approx. 2.5 VA15HLC LS+PH-PL control line8|. solenoid powersupply positive electrodeEngine idling, El position:Approx. 5.0 VA16SH LS+Shift control linear solonoid oowersupply positive electrodeEngine idling, E position:Approx. 6.0 V417Ground
A18Not used
A19Not used
420D INDE indicator light controlWhen l9l indicator light comes on: Approx. jO VWhen lll indicator lighr OFF: 0 VA2'lNot used
422Not used
VBUBack-up power systemAlways battery voltage424Not used
A.25tG1Power supply systemWith ignition switch ON (lt): Baftery voltageWith ignition switch OFF:0 VPG1Ground
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