Description
Power Flow lcont'd)
lst Gear (8. E or E positionl
In E, E, or D position, the optimum gear is selected from 1st, 2nd, 3rd, and 4th gears, according to conditions such 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, and the mainshaft 1st gear
rotates.
2. Power is transmitted to the countershaft 1st gear. which drives the countershaft via the one-way clutch.
3. Power is transm itted to the final drive gear.which drives the final driven gear and the transfer shaft drive gea r (4WD).
4. The transfer shaft drive gear drives the transfer shaft and the transfer driven gear shaft (4WD).
NOTE:
o In @, @, @, or E position. hydraulic pressure is not applied to the 1st-hold clutch.. The illustration shows the 4WD automatic transmission; power flow of the 2WD automatic transmission is identicalto the 4WD except for parts related to the transfer assembly.
CONVERTERMAIiISHAFT1ST
CLUTCH
MAINSHAFT
COUNTERSHAFT
FINAL OBIVE GEAR
ONE.WAY CLUTCH
PARK GEAR
FINAL DRIVEN GEAR
14-10
TRANSFER SHAFT DRIVE GEAR {4WD}
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Description
Electronic Control System (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 vehicle speed
sensor, the throttle position sensor, the barometric pressure sensor ('98 model). the engine coolant temperature sensor, the
brake switch signal, and the shift lever position signal, to control shifting while the vehicle is ascending or descending a
slope, or reducing speed.
SIGNALS DETECTED
Driving Rcsisl.nce
Judgemont ot Controlling Aroa
. Normal Modo {Flrt ro.d mode}. Ascending Mode. Deacending Mode. Deceleration Mode
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Description
Electronic Control System (cont'd)
Descending Control
When the PCM determines that the vehicle is going down a hill in E and @ positions ('97 - 98 models). and in @ posi-
tion {'99 - 00 models), the shitt-up speed from 3rd to 4th gear and from 2nd to 3rd (when the throttle is closed) becomes
faster than the set speed for flat road driving to widen the 3rd gear and 2nd gear driving areas. This, in combination with
engine braking from the deceleration lock-up, achieves smooth driving when the vehicle is descending. There are three
descending modes with different 3rd gear driving areas and 2nd gear driving areas according to the magnitude of a gradi-
ent stored in the PCM. When the vehicle is in 4th gear, and you are decelerating when you are applying the brakes on a
steep hill, the transmission will downshift to 3rd gear, When you accelerate, the transmission will then return to higher
gear.
2ND - 3RD 3RD - 4TH
o50
F
DESCENDING MODE: Downshift Schodule
- : FLAT ROAD MODE
----'-----' I GRADUAL DESCENDING MODE
- - - - - : MEDIUM OESC€NOING MODE
. . ... : STEEP DESCENDING MODE
62 mph Vehicle sp€ed1100 km/hl
Deceleration Control
When the vehicle goes around a corner, and needs to decelerate first and then accelerate, the PCM sets the data for deceleration
control to reduce the number of times the transmission shifts. When the vehicle is decelerating from speeds above 27 mph(4i| km,ih), the PCM shifts the transmission from 4th to 2nd earlier than normal to cope with upcoming acceleration,
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Lock-up System
TOROUE CONVERTER
In E position ('97 - 98 models) and in E position ('99 -
OO models) (3rd and 4th), and E position ('97 - 98 mod-
els) and in E position with Over-Drive (O/D) is OFF (by
pressing the O/D switch) ('99 - 00 models) (3rd), pressur-
ized fluid is drained from the back of the torque convert-
er through a fluid passage, causing the lock-up piston to
be held against the torque converter cover, As this takes
Dlace, the mainshaft rotates at the same speed as th8
engine crankshaft. Together with the hydraulic control,
the PCM optimizes the timing of the lock-up system.
Under certain condltions. the lock-up clutch is appli€d
during deceleration, in 3rd and 4th gear.
The lock-up system controls the range of lock-up sccord-
ing to lock-up control solenoid valves A and B, and ths
linear solenoid. When lock-up control solenoid valves A
and B activate. modulator pressure changes. Lock-up
control solenoid valves A and B are mounted on the out-
side of the torque converter housing, and the linear
solenoid is mounted on the transmission housing. They
are controlled bv the PCM.
The table below shows the lock-up conditions for lock-up
control solenoid valves and linear solenoid pressure.
LINEAR SOLENOID PRESSURE
(cont'd)
LOCK.UP CONTROL' VALVE
LOCK.UP CONTROLSOLENOID VALVE
AB
MODULATORPf,ESSURE
MAINSHAFT
COUNTERSHAFT
SUB.SHAFT
Lock-up
Conditions
Lock-up Conirol
Solenoid valveLinaal
Solenoid
PrgssulsAB
Lock-up OFFOFFOFFHigh
Lock-up, HalfONDuty operation
OFF - ONLow
Lock-up, FullONONHigh
Lock-up
during
deceleration
ONDuty operation
OFF - ON
RELIEF VALVE
LOCK'UP TIMINGVALVE
COOLER RELIEF VALVE
ATF COOLERATF STRAINER
ATF PUMP
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PCM CONNECTOR B (25P) lcont'd)
PCM CONNECTOR C {31PI
PCM CONNECTOR D II6PI
Terminal NumbelSignalDescriptionMeasuring Conditions/Terminal voltage
811SHBShift control solenoid valve B
control
In E, E position, in 1st and 2nd gear in -q,
Er position: Battery voltage
In B position, in 3rd gear in qd, q:l,in atn
gear in D. position: 0 V
812ILUlnterlock controlWhen ignition switch is ON (ll), brake pedal
deDressed and accelerator oedal released:0 V
B13D4 INDD4 Indicator light controlWhen ignition switch is first turned ON (ll): 6 V
or more for tlvo seconds
In lDll position: 6V or more
814NMSGMainshaft speed sensor ground
815NMMainshaft speed sensor signal
InpuI
Depending on engine speed: Pulsing signal
When engine is stopped: 0 V
816ATP RAy'T gear position switch Eposition signal input
In E position; OV
In other than E position: Battery voltage
817ATP 2Ay'T gear position switch E posi-
tion signal input
InEposition:0V
In other than E position: Battery voltage
B18ATP 1A/T gear position switch El posi-
tion signal input
InEposition:0V
In other than E position: Battery voltage
819 to 821Not used
B 22NCSGCountershaft speed sensor ground
NCCountershaft speed sensor signal
Inpur
Depending on vehicle speed: Pulsing signal
when vehicle is stooped: 0 V
824ATP D4A/T gear position switch iql posi-
tion signal input
In E position: 0V
In other than lgal position: Baftery voltage
825ATP NPAy'T gear position switch E and
N position signals input
In E and E positions: 0V
In otherthan @ and ffi positions:5 V
Terminal NumberSignalDescriptionMeasuring Conditions/Terminal Voltage
SCSService check signalWith ignition switch ON (ll) and service check
connector open: 5 V
With ignition switch ON (ll) and service check
connector connected with special tool: 0 V
c10VBUBack-up power system(under-hood Fuse 47)
Always battery voltage
Terminal NumberSignalDescriptionMeasuring Conditions/Terminal Voltage
STOP SWBrake switch signal inputBrake pedal pressedr Battery voltage
Brake pedal released: 0 V
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Terminal NumborSignalDescriptionMeasuring Conditions/Terminal Voltage
D1LCALock-up control solenoid valve A
control
During lock-up conditions: Baftery voltage
During no lock-up condition: 0 V
D2SHBShift control solenoid valve B
control
Battery voltage in following positions:
. E, E and positions
. E, -ql, and E positions in lst and 2nd gear
0 V in following positions:
. E, E;, and E positions in 3rd gear
. E and E positions in 4th gear
. E, El, and El positions
D3LCBLock-up control solenoid valve B
control
During full lock-up conditions: Battery voltage
During half lock-up conditions; Pulsing signal
D4Not used
D5VB SOLPower supply for solenoid valves
(Under-hood Fuse 15)
With ignition switch ON (ll); Battery voltage
With ignition switch OFF: 0 V
D6ATP RAy'T gear position switch
B position input
In E position: OV
In other than E position: Baftery voltage
D7SHAShift control solenoid valve A
control
Battery voltage in following positions:
. E position
. E, E, and E positions in 2nd and 3rd gear
. E position
0 V in following positions:
. E position. E. E, and E positions in lst gear
. Erl and E positions in 4th gear
.EandEpositions
D8
{'98 model}
ATP D3Ay'T gear position switch
E position input
In E position: 0V
In other than E position: Baftery voltage
D8
('99 - 00 models)
O/D SWOver-Drive (O/D) switch signal
input
When Over-Drive {O/D) is OFF (O/D OFF
indicator light is ON): 0 V
When Over-Drive {O/D) is ON {O/D OFF
indicator light is oFF): Battery voltage
D9ATP D4A/f gear position switch
E position input
In E position: 0V
In other than E position: 5 V
D10NCCountershaft sDeed sensor inoutDepending on vehicle speed: Pulsing signal
when vehicle is stopped: Approx.0 V
Dl1NMMainshaft speed sensor inputDepending on vehicle speed: Pulsing signal
When engine is stopped: Approx. 0 V
D12NMSGMainshaft speed sensor ground
D13ATP NPA,/T gear position switch E and
El positions input
InEandEpositions: 0V
In other than E and m position: 5 V
D14AlP 2A/T gear position switch
El position input
InE position; 0V
In other than E position: Battery voltage
D15ATP 1A,/T gear position switch
E position input
InEposition:0V
ln other than El position: Battery voltage
D16NCSGCountershaft speed sensor
grouno
PCM CONNECTOR D (16P)
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Symptom-to-Component Chart
Hydraulic System (cont'd)
SYMPTOMCheck these items on thePROBABLE CAUSE ListCheck these items onthe NOTES Lisr
Shift lever does not operate smoothly.o, JdPFails to shift; stuck in 4th gear.14, 41 , 48
Transmission will not shift into park in E position.6, 38, 61PStall rpm high; all clutch pressures are in specification.40D,K,OLock-up clutch does not disengage.18, 43, 44, 45, 46, 49,50,57
Lock-up clutch does not operate smoothly.14, 40, 43, 44, 45, 46, 49, 50. 57Lock-up clutch does not engage.'t8, 40, 43, 44, 45, 46, 49, 50, 56, 57Vibration in all positions.
No engine braking in I position.59
Shift position indicator does not indicate anv position,6. 38, 60
PROBABLE CAUSE
I 33 Thrust washer worn/damaged
ATF pump worn or binding34Clutch clearance incorrect
Regulator valve stuck or regulator valvespflng wornDrive plate delective or transmission mtsas-sembled
Servo valve stuck5ttTorque converter housing or transmissionhousing bearing worn/damagedMainshaft worn/damaged
Shift cable broken/out of adjustmentATF strainer clogged
7Final gears worn/damaged38Shift cable is worn where it attaches to thetransmission or at the body mountsIOne-way (sprag) clutch worn/damaged
1st gears worn/damaged {2 gears)39Modulator valve stuck10lst clutch defective40Torque converter check valve stuck112nd gears worn/damaged (2 gears)41Foreign material in separator plate't22nd clutch defectiveCPB valve stuck
t53rd clutch defective43Lock-up timing valve stuck144th clutch defective44Lock-up shift valve stucktcReverse gears worn/damaged (3 gears)Lock-up control valve stuck16Excessive ATF46Lock-up clutch Diston defective17Torque converter one-way clutch defective47Shift control solenoid valve A defecttve
18Linear solenoid assemblv defective (,98 - OOmodels)48Shift control solenoid valve B dsfectrve
49Lock-up control solenoid valve A defective'19CPC valve stuckLock-up control solenoid valve B deleqtve20l-2 shift valve stuck51Servo control valve stuck212-3 shift valve stuck52lst accumulator defective3-4 shift valve stuck53Foreign material in 2nd exhaust orifice2nd accumulator defective54Foreign material in 3rd exhaust orifice3rd accumulator defectiveForeign material in 4th exhaust orifice4th accumulator defective56Mainshaft speed sensor defective262nd orifice control valve stuckCountershaft speed sensor defective273-4 orifice control valve stuck583rd sub accumulator defective2aForeign material in main orifice59lst-hold clutch defective29Foreign material in lst orifice60A/T gear position switch defective or out ofadjustment30Foreign material in reverse orifice
31Engine output low61Park gear mechanism defective32Needle bearing worn/damaged
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Symptom-to-Com ponent Chart
Hydraulic System (cont'd)
NOTES
See flushing procedure, page l4-264 and 265,
BSet idle rpm in gear to specified idle speed. lf still no good, adjust motor mounts as outlined in enginesection of this manual.
clf the large clutch piston O-ring is broken, inspect the piston groove for rough machining.
Dlf the clutch pack is seized or is excessively worn. inspect the other clutches fot wear, and check the orificecontrol valves, CPC valve, and linear solenoid for free movement.
lf the linear solenoid is stuck, inspect the clutches for wear.
lf the 1-2 shift valve is stuck closed. the transmission will not upshift. lf stuck open, the transmission hasno lst gear.
Hlf the 2nd orifice control valve is stuck, inspect the 2nd and 3rd clutch Dacks for wear.
lf the 3-4 orifice control valve is stuck, inspect the 3rd and 4th clutch packs for wear.
Jlf the clutch pressure control valve is stuck closed. the transmission will not shift out of lst gear.
Klmproper alignment of main valve body and torque converter housing may cause ATF pump seizure. Thesymptoms are mostly an rpm-related ticking noise or a high-pitched squeak.
Llf the ATF strainer is clogged with particles of steel or aluminum, inspect the ATF pump and differentialpinion shaft. lf both are OK and no cause for the contamination is found, replace the torque converter.
Mlf the lst clutch feed pipe guide in the end cover is scored by the mainshaft. inspect the ball bearing forexcessive movement in the transmission housing. lf oK, replace the end cover as it is dented. The o-rinounder the guide is probably worn.
N' Replace the mainshaft if the bushing for the 4th feed pipe is loose or damaged, lf the 4th feed pipe is darrFaged or out of round. replace the end cover.' Replace the mainshaft if the bushing for the l st feed pipe is loose or damaged. lf the 1st feed pipe is dam-aged or out of round, replace it.
oA worn or damaged sprag clutch is mostly a result of shifting the transmission in E!. E, or E positionwhile the wheels rotate in reverse. such as rocking the vehicle in snow.
PInspect the frame for collision damage.
lnspect for damage and wear:
l. Reverse selector gear teeth chamfers.
2. Engagement teeth chamfers of countershaft 4th and reverse gear.
3. Shift fork for scuff marks in center.
4. Differential pinion shaft for wear under pinion gears.
5. Bottom of 3rd clutch for swirl marks.
Replace items 1, 2, 3. and 4 if worn or damaged. lf transmission makes a clicking, grinding, or whirring noise,also replace mainshaft 4th gear, reverse idler gear, and countershaft 4th gear in addition to 1,2, 3, or 4.lf differential pinion shaft is worn, overhaul differential assembly, replace ATF strainer, and thoroughly cjeantransmission, flush torque converter. cooler, and lines,lf bottom of 3rd clutch is swirled and transmission makes gear noise. replace the countershaft and final drivenoear,
Be very careful not to damage the torque converter housing when replacing the main ball bearing. you
may also damage the ATF pump when you torque down the main valve body. This will result in ATF pumpseizure if not detected. Use the Drooer tools.
SInstall the main seal flush with the torque converter housing. lf you push it into the torque converterhousing until it bottoms out, it will block the fluid return passage and result in damage.
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