Why is there no drive to the rear wheels of my Subaru?
I have a Subaru Legacy Lancaster, which is a Japanese version of the Outback.
I've checked there's no fuse in the FWD slot, and the driveshaft back to the wheels is all good.
There are no sounds that indicate something mechanical being broken.
Occasionally when I accelerate hard there's a thump that shakes the car, changing its attitude on the road, as if it briefly jumps into 4WD. I'm starting to suspect the sensor that feels if the tranny is binding on corners and tells the solenoid to release the drive to the rear wheels. Perhaps the sensor (if there is one) is faulty, and is causing the solenoid to be permanently on, stopping drive to the rear wheels. Any comments/suggestions?
Did you know that there is a fuse under hood on Passenger side that I have seen people put the fuse in the missing spot. Problem is it is only for towing the car. Remove if fuse is present and see if it fixes your problem.
The fuse is only for when you are running a smaller sized spare tire. You have to put one in when you put the spare on to make the car FWD only. Go only far enough to get the tire replaced. Do not drive the car extended distances in FWD.
The starter is separate from the soleniod; It could be a part called the bendix on the starter itself. If you can remove it, take it to a auto parts store- they will check it for free.
there is a plug on the shaft-side of the differential. Using a ratchet remove the plug and with the engine OFF, stick your finger inside the hole and you should get fluid just below the threads of where the plug goes in.
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the only way you can do this is if you can identify the gear ratios from both cars with the transmission codes found on the strut tower plate.
see this list to check for matches, read it carefully its a ton of info subarugears narod ru
the biggest draw back that you will have to check first is the ratio of the diffs you want to change. If they are not the same but will fit then you will destroy the 3rd diff in the transmission from excessive use.
you will likely need to replace the following:
Duty C Solenoid
Transfer Clutch Pack
Reduction gear
All of these parts are located in the tail end of the 4EAT automatic transmissions. The reduction gear can separate from its hub and damage the above mentioned parts too.
Hi there now you say that occasionally the behaviour changes and it feels like you have all 4 wheels driving. Now is there any chance that the previous owner has modified the sensor or bridged it out to stopthe 4 wheels from driving.
Now firstly you need to establish if it will engage all four wheels to drive by simply jacking up one side of the car and putting it into drive and watch to see if the elevated wheels drive while in gear.
The whole idea of the anti bind solenoid is to allow the rear driving wheels to revert back to a conventional differential to allow you to corner efficiently.
Now in my opinion I would find the terminals for the duty c solenoid and disconnect them and simply get a battery or run a power source from the main battery and simply give the solonoid a feed
direct from your power supply and listen for it engaging and disengaging to see if yhe solenoid bis actually operational. It could simply be stuck in the on position like a starter motor sticks and the bang you're hearing when u accelerate hard may simply be the solenoid being forced back to its natural position of being off
The high acceleration from the vehicles engine would also cause a surge of electrical power and may be causing the solenoid to revert back as it may just be stuck on.
1. Check the solenoid for operation using an external or direct power source listen for it clicking on n off
2. The solenoid bind sensor may be faulty or bridged out to only allow fwd. So find it and check out the wiring for breaks and bridge wiring which would keep the solenoid engaged
3. Check all the fuses and relays especially as solenoids tend to use relays rather than a fuse
In my opinion this may just be a simple case of a stuck solenoid keeping your 4 wd on a 2wd basis.
Find the sensor and check the wiring and if possible remove the rear differential solenoid and check for operation.
Try this above and get back to me as it could be linked to your liaf sensing valve and the throttle potentiometer. But lets start of with simple elimination of the solenoid and its sensor
hope this helps
thanks davy
IT is a constant all wheel drive car which means that all 4 wheels are driven all of the time . There is a differential in the centre that allows for different speeds between front and back while driving such as going over bumps . When you engage the 4wd button you are in effect locking that centre diff so that both front and rear axles drive together. If you have it so that 4wd is not engaged (selected ) and there is no drive action to the rear wheels that then indicates that the shaft in that centre diff is not connected in the side gears ( stripped /broken) and it has been in 4wd all the time so that it could be sold
easiest way to tell if it is 2 wheel or 4 wheel is look under the car.
From the front of the vehicle just off center (could be left or right) there will be a differential. (much like what you see under the rear of a pickup truck. If you see this it's a 4wd or awd.
The difference between awd and 4wd is-
4wd is either front or rear wheel drive with the ability to (now days) push a button and "lock in" the other axel.
Awd is at all times, all 4 wheels are working together to move the vehicle.
{ ... ENGINE TORQUE DISTRIBUTION – DIRECTING THE FLOW
OF POWER
In an all-wheel-drive vehicle, engine power can be
directed to all four wheels. Subaru Symmetrical AWD differs slightly
from model to model in how it directs power to the wheels, depending on
its transmission.
MODELS
WITH FIVE-SPEED MANUAL TRANSMISSION – CONTINUOUS ALL-WHEEL DRIVE:
A viscous-type locking center differential and limited-slip rear
differential help distribute torque – normally configured at a 50/50
split front to rear. If wheel speed differs between front and rear
axles, the center and/or rear differentials lock up to help distribute
power to the wheels with the most traction.
MODELS
WITH FOUR-SPEED AUTOMATIC TRANSMISSIONS – ACTIVE ALL-WHEEL DRIVE:
An electronically controlled variable transfer clutch and limited-slip
rear differential distribute power to where traction is needed. Sensors
monitor parameters such as wheel slippage, throttle position, and
braking to help determine torque distribution and direct it to the
wheels with optimum traction.
MODELS
WITH FIVE-SPEED AUTOMATIC TRANSMISSION – VARIABLE TORQUE DISTRIBUTION
ALL-WHEEL DRIVE: As with Active All-Wheel Drive, an
electronically controlled variable transfer clutch distributes power,
but through a planetary-type center differential and a viscous-type
limited-slip rear differential. Torque distribution is normally
configured at a performance-oriented rear-wheel-biased 45/55 split front
to rear. Sensors monitor the same parameters as for Active All-Wheel
Drive.
WRX STI,
WITH SIX-SPEED MANUAL TRANSMISSION – DRIVER CONTROLLED CENTER
DIFFERENTIAL (DCCD) ALL-WHEEL DRIVE: The STI uses an
electronically managed multi-plate transfer clutch and a mechanical
limited-slip differential in conjunction with a planetary-gear-type
center differential to control power distribution between the front and
rear wheels. Featuring manual and three automatic modes, DCCD is
normally configured at a 41/59 split front to rear. Sensors monitor
parameters such as wheel slippage, steering angle, throttle position,
and braking to help determine torque distribution and direct it to the
wheels with optimum traction. DCCD also features a limited-slip helical
front and Torsen® rear differential. ... }
And what are the symptoms? How do you know the coupling to the rear is not working?
Did you know that there is a fuse under hood on Passenger side that I have seen people put the fuse in the missing spot. Problem is it is only for towing the car. Remove if fuse is present and see if it fixes your problem.
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