1997 HONDA CR-V dual pump

Precautions for Real-time 4WD (Four-wheel Drivel
Under normal conditions, the vehicle is in 2WD (front-wheel drive). However, the system will instantly transmit
appropriate driving force to the rear wheels {depending on the driving force of the front wheels and the road conditons)
The Real-time 4WD-Dual Pump System does not have a manual switch to disable the 4WD system. Whenever service
work requires spinning the front or rear wheels with the engine, always lift up and support the vehicle so all lour wheels
are off the ground (see page 1- 19).
1-23
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PGM-FI Main Relay
Description
The PGM-Fl main relav actuallv contains two individual
relays. This relay is located at the passenger side of the
cowl. One relay is energized whenever the ignition is on
which supplies the battery voltage to the ECM/PCM,
power to the fuel injectors, and power for the second
relay. The second relay is energized for two seconds
when the ignition is switched on, and when the engine
is running, to supply power to the fuel pump
PGM.FIMAIN RELAY
Belay Testing
NOTE: lf the engine starts and continues to run, the
PGM-FI main relay is OK.
1. Remove the glovebox and the passenger's dash-
board lower cover (see section 20).
2. Remove the PGM-FI main relay
3. Aftach the battery positive terminal to the No. 2 ter-
minal and the battery negative terminal to the No. 1
terminal of the PGM-Fl main relay. Then check for
continuity between the No. 5 terminal and No. 4 ter-
minal of the PGM-FI main relay
. lfthere is continuity, go on to step 3.
. lf there is nocontinuity, replacethe PGM-Fl main
relav and retest.
No.2
To lGN. 1
To GROUND
To ST. SWITCH
To ECM/PCMCONNECTORTERMINAL A16(FLR)
To BAT O
To FUEL PUMPTo ECM/PCMCONNECTORTERMINAL(411 and A24,Bl .nd Bgal(IGP)
To FUEL PUMP
98 - 00 models
Attach the batterv Dositive terminal to the No. 5 ter-
minal and the battery negative terminal to the No. 3
termjnal of the PGM-Fl main relay. Then check that
there is continuity between the No. 7 terminal and
No. 6 terminal of the PGM-FI main relay.
. lf there is continuity, go on to step 4.
. lf there is nocontinuity, replacethe PGM-Fl main
relay and retest.
Attach the batterv oositive terminal to the No.6 ter-
minal and the battery negative terminal to the No. 1
terminal of the PGM-Fl main relay. Then check that
there is continuitv between the No. 5 terminal and
No. 4 terminal of the PGM-Fl main relay.
. lf there is continuity, the PGM-Fl main relay is OK.
. lf there is nocontinuity, replacethe PGM-FI main
5.
(cont'd)
11-147
No.5 No.5
relay and retest.
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Differential
Rear Differential
Special Tools .......... ...........15-2
Description
Rear Differential ................................. 15-4
Hydraulic Flow ............ ,.. 15-6
Real-time 4WD-Dual Pump System
Troub|eshootin9 ................................. 15-10
Rear Differential Assembly
Troubleshooting ................................. 15-13
Maintenance
Differential Fluid ........... . 15-14
Rear Differential Assembly
lllustrated Index .......... .. 15-15
Removal/lnstallation .... 15-16
Differential Carrier Assembly
Leak Repair .................... 15-18
OilSeals
Replacement ...,................................... 15-19
Rear Differential Assembly
Disassembly ..........,......., 15-20
Reassembly .................... 15-23
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Description
Rear Differential
Outline
The Real-time 4WD-Dual Pump System model has a hydraulic clutch and a differential mechanism in the rear differential
assembly. Under normal conditions, the vehicle is driven by the front wheels. However, depending on to the driving force
of the front wheels and the road conditions. the system instantly transmits appropriate driving force to the rear wheels
without requiring the driver to switch between 2WD (tront wheel drive) and 4WD (four wheel drive). The switching mecha-
nism between 2WD and 4WD is integrated into the rear differential assembly to make the system light and compact.
ln addition, the dual-pump system switches off the rear-wheel-drive force when braking in a forward gear. This allows the
braking system to work properly on models equipped with an Anti-lock Braking System (ABS).
Construction
The rear differential assembly consists of the torque control differential case assembly and the rear differential carrier
assembly. The torque control differential case assembly consists of the differential clutch assembly, the companion
flange, and the oil pump body assembly. The rear differential carrier assembly consists of the differential mechanism. The
differential drive and driven gears are hypoid gears.
The oil pump body assembly consists of the front oil pump, the rear oil pump, the hydraulic control mechanism, and the
clutch piston. The clutch piston has a disc spring that constantly provides the differential clutch assembly with a preset
torque to Drevent abnormal sound.
The clutch guide in the differential clutch assembly is connected to the propeller shaft via the companion flange, and it
receives the driving force lrom the transfer assembly. The clutch guide rotates the clutch plate and the front oil pump in
the oil pump body.
The clutch hub in the differential clutch assembly has a clutch disc that is splined with the hypoid drive pinion gear. The
hypoid drive gear drives the rear oil pump.
The front and rear oil pumps are trochoidal pumps. The rear oil pump capacity is 2.5 percent larger that the front oil pump
to handle the rotation difference between the front and rear wheels caused by worn front tires and tight corner braking.
The oil pumps are designed so the fluid intake works as a fluid discharge when the oil pumps rotate in reverse. Genuine
Honda CVT fluid is used instead of differential fluid.
Operation
When there is a difference in rotation speed between the front wheels (clutch guide) and rear wheels (hypoid driven gear),
hydraulic pressure from the front and rear oil pumps engages the differential clutch, and drive force from the transler
assembly is applied to the rear wheels.
The hydraulic pressure control mechanism in the oil pump body selects 4WD mode when the vehicle is started abruptly,
or when accelerating in a forward or reverse gear (causing rotation difference between the front and rear wheels). or
when braking in reverse gear {when decelerating). lt switches to 2WD mode when the vehicle is driven at a constant speed
in forwar! or reverse gear (when there is no rotation difference between the front and rear wheels), or when braking in a
fo rwa rd gear (when decelerating).
To protect the system, the differential clutch assembly is lubricated by hydraulic pressure generated by the oil pumps in
both 4WD and 2WD modes. Also, the thermal switch relieves the hydraulic pressure on the clutch piston and cancels 4WD
mode if the temDerature of the differential fluid rises above normal.
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Description
Hydraulic Flow
Forward Start and Acceleration l4WD)During a forward start and forward acceleration, the dual pump system can engage four wheel drive.lf the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front pump
draws fluid through check valve B and discharges it. Some of the discharged fluid is drawn in the by the rear oil pump.The remaining fluid will pass through check valve E into the clutch piston. There, hydraulic pressure is regulated by twoorifices.
The regulated hydraulic pressure at the clutch piston pushes the plates and discs of the clutch together to form a connec-tion. The engaged clutch then passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRrFtcEsFRONT OIL PUMPREAR OIL PUMP
Forward Driving at Constant Speed lzWD)When driving forward at a constant speed (cruising), the dual pump system functions in two wheel drive mode.The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same.Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. Becausethere is no pressure built up at the clutch piston, the clutch does not engage, and the vehicle remains in 2WD (front wheeldrive).
FRONT OIL PUMP
15-6
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Forward Deceleration l2WDl
During forward deceleration, the dual pump system functions in two wheel drive mode.
Because of braking characteristics, the speed of the rear wheels may exceed the speed ol the front wheels during deceler-
ation. lf so, the rear oil pump spins faster than the front oil pump.
Fluid discharged by the rear oil pump is simply drawn in again by the rear pump and recirculated. Because there is no
pressure built up at the clutch piston. the clutch piston does not engage, and the vehicle remains in 2WD (front wheel
drive).
Reverse Start and Acceleration (4WD)
During reverse start and reverse acceleration, the dual pump system can engage four wheel drive.
lf the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front oil
pump draws in fluid through check valve A and discharges it. {Note that in reverse, the direction of the pumps is the oppo-
site of that during forward driving.)
Some of the fluid that is discharged by the front oil pump is drawn in by the rear oil pump. The remaining fluid passes
through check valve F into the cylinder of the clutch piston, where it is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a con-
nectlon. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRtFtcEsFRONT OIL PUMP
{cont'd)
15-7
REAR OIL PUMP
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Description
Hydraulic Flow (cont'dl
Reverse Driving at Constant Speed l2WD)when driving in reverse at a constant speed, the dual pump system functions in two wheel drive mode.The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same,Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. But, becausethe there is a difference in the capacity between the two pumps, fluid flows through check valve E, and then through ori-Iices. This fluid lubricates and cools the clutch assembly and bearings.ls this condition, only a low pressure is built up at the clutch piston. Therefore the clutch does not engage, and the vehicleremains in 2WD (front wheel drive).
Reverse Deceleration l/tWDl
During reverse deceleration, the dual pump system can engage four wheel drive.When decelerating in reverse direction, the speed of the rear wheels may exceed the speed of the front wheels (due toengine braking). In this condition, the rear oil pump draws fluid through check valves B and C. Fluid discharged from therear oil pump then flows through check valve E to the clutch piston. There, pressure is regulated by two orifices.The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a con,nection. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRtFtcEsREAR OIL PUMP
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Real-time 4WD-Dual Pump System
Troubleshooting (Automatic Transmissionl
When starting and accelerating in forward gesrs {4WDmodel
1. Lift up the vehicle so all four wheels are off theground (see section 1).
2. Make a mark on either No.
shaft.
'I or No.2 propeller
PROPELLER SHAFT
Start the engine, and let it run until it warms up (the
radiator fan comes on at least twice).
With the engine at idle. shift to the E position.
Apply the parking brake firmly. and measure thetime it takes the propeller shaft to rotate 10 times.. lf the measured time is more than 10 seconds,
the 4WD system is normal.
. lf the time is less than 10 seconds, there is aproblem in 4WD system. Check the differential
fluid. lf the differential fluid is normal, replace
the torque control differential case kit.
15-10
When starting and accelerating in revGrsg gear {4WDmodel
1. Lift up the vehicle so all four wheels are off theground (see section 1).
Make a mark on either No.
shaft.
1 or No. 2 propeller
PROPELLER SHAFT
Start the engine. and let it run until it warms up (the
radiator fan comes on at least twicei.
With the engine at idle, shift to the E position.
Apply the parking brake firmly, and measure the
time it takes the proDeller shaft to rotate 10 times,. lf the measured time is more than 10 seconds,
the 4WD system js normal.. lf the time is less than 10 seconds, there is aproblem in 4WD system. Check the differential
fluid. lf the differential fluid is normal, reolace
the torque control differential case kit.
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