1998 HONDA CIVIC speed

Description
Power Flow (cont'dl
lst Gesr (E or @ position)
In lE or E position, the optimum gear is automatically selected from 1st,2nd,3rd and 4th gears, according to conditionssuch as the balance between throttle opening (engine load) and vehicle speed.
1. Hydraulic pressure is applied to the 1st clutch, which rotates together with the mainshaft, causing the mainshaft 1stgear to rotate.
Power is transmitted to the countershaft 1st gear, which drives the countershaft via the one-way clutch.
Power is transmitted to the final drive gear, which drives the final driven gear.
TOROUE CONVERTER
MAINSHAFT 1ST GEAR
lST CLUTCH
MAINSHAFT
AY CLUTCH
FINAL DRIVE GEAR
PARK GEAR
L
COUNTERSHAFT1ST GEAR
14-8

2nd Gear {8, E or E position)
E Position is provided to drive only 2nd gear.
1. Hydraulic pressure is applied to the 2nd clutch on the mainshaft, and power is transmifted via the 2nd clutch to the
mainshaft 2nd gear.
2, Powet transmitted to the mainshaft 2nd gear is conveyed via tho countorshaft 2nd gear, which drivos the counter-
shaft.
3. Power is transmined to the final drivB gear, which drives the final driven ge8r.
NOTE: Hydraulic pressure is also applied to the 1st clutch, but since the rotation speed of ths 2nd gear excaads that
of lst gear, power from 'lst gear is cut off at the one-way clutch.
TOROUE CONVERTER
2ND CLUTCH
MAII'ISHAFT
COUNTEBSHAFT 2I{D GEAR
(cont'd)
14-9

Description
Power Flow (cont'dl
3rd Gear (bl or bd positionl
1. Hydraulic pressure is applied to the 3rd clutch. Power from the mainshaft 3rd gear is transmitted to the countershaft3rd gear.
2. Power is transmitted to the final drive gear, which drives the tinal driven gear.
NOTE: Hydraulic pressure is also applied to the 1st clutch, but since the rotation speed of 3rd gear exceeds that of 1stgear, power from lst gear is cut off at the one-way clutch.
TOROUE CONVERTER
MAINSHAFT 3RD GEAR
MAINSHAFT
COUNTERSHAFT
3RD GEAB
3RD CLUTCH
14-10
DRIVEN GEAR

4th cear lE position)
1. Hydraulic pressure is applied to the 4th clutch, which rotates together with the mainshaft, causing the mainshaft 4th
gear to rotate.
2. Power is transmitted to the countershaft 4th gear' which drives the countershaft'
3. Power is transmitted to the final drive gear, which drives the final driven gear'
NOTE: Hvdraulic pressure is also applied to the lst clutch, but since the rotation speed of 4th gear exceeds that of 1st
gear, power from 1st gear is cut off at the one-way clutch
TOROUE
MAINSHAFT 4TH GEAR
COUNTERSHAFT
FINAL ORIVEN GEAR
14-11

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

GRADE LOGIC CONTROL SYSTEM
How it works:
The pCM compares actual driving conditions with driving conditions memorized in the PCM, based on the input from the
vehicle speed sensor, the throttle position sensor, the barometoric pressure sensor, the engine coolant temperature sensor,
the brake switch signal, and the shift lever position signal, to control shifting while a vehicle is ascending or descending a
slope, or reducing speed.
SIGNALS OETECTED
O.iving Resi3lence
Judgemenl ot Conirolling Arca
. Ascending mod€
lFuzzy loqicl. Gradual Ascending mode' Ste€p Ascending mode. Oescending mode. Gr.du.l Descending mode. Steep D6cending mode
14-15

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
Hydraulic Flow (cont'd)
2nd G.!r
As tha speed of the vehicle reaches the prescribed value, shift control solenoid valve A is turned oN by means of thePCM The modulator pressure {64} in the left end of the 1-2 shift valve is r€leased by turning shift controt sotenoidvalve A oN The 1-2 shift valve is moved to the left side and uncovers the port to allow line pressure {5) to the z-3shift valve. The line pressure (5) changes to the 2nd ctutch pfessure l2O) at the 2-3 shift valve. The 2nd clutch pressure(20) is applied to the 2nd clutch, and the 2nd clutch is engaged.
Fluid flows by way of:- Line Pressure (4) + cPB varve - Line pressure (s) * 'r-2 shift varve - Line pressure (5) * 2-3 shift varve- 2nd Clutch Pressure (20) + 2nd Clutch
The hydraulic pressure also flows to the 1st clutch. However, no power is transmittod because of the one-way ctutch.
NOTE: When used, "|eft" or ,,right,, indicates direction on the hydraulic circuit.
\-
14-28