1995 Subaru Impreza 1.8L AT - Question on AWD

[07Evolved]

My buddy is looking to buy a 1995 Subaru Impreza 1.8L AT he found on craigslist. He called the guy and the guy said that he took the rear driveshaft out because he didn't want the AWD to engage all the time and so now it is FWD...makes sense.

But the question I have to everyone is (just want to make sure), this car should be AWD all the time, correct? The guy said that there is a sensor in the transmission that is going bad and he claims this sensor tells the trans when to go into AWD when needed. Is there a sensor that does this? Does the computer sense the road conditions and then tell the trans to go into AWD or is the car AWD all the time? I just want to make sure I am correct on this. My buddy and I are going to look at the car today.

I thought our cars were AWD all the time no matter what, unless of course you took out a driveshaft like this guy did.

Any info would be helpful....I just don't the guy knows what he is talking about, but I want to make sure.

Thanks!

[kimokalihi]

As far as I know, AWD means it's AWD all the time. It just gives different amount of power to the front or rear at different times. That's what I always thought but I could be wrong.

[07Evolved]

As far as I know, AWD means it's AWD all the time. It just gives different amount of power to the front or rear at different times. That's what I always thought but I could be wrong.

Thanks Kimo, that is what I thought too. I appreciate the quick response. I just think this guy doesn't really understand the Subaru concept of AWD.

[log1call]

I would suspect the trans is having a problem and he has pulled the driveshaft to hide the problem.
The rear wheels are only meant to get as much drive as they need to prevent wheel spin, sometimes they get too much drive and you get "torque bind".
Do a serch on here for "torque bind" and you will see the symptoms and can ask him about it.

[07Evolved]

I would suspect the trans is having a problem and he has pulled the driveshaft to hide the problem.
The rear wheels are only meant to get as much drive as they need to prevent wheel spin, sometimes they get too much drive and you get "torque bind".
Do a serch on here for "torque bind" and you will see the symptoms and can ask him about it.

thank you!

[Buffman]

maybe he's blabbling on about the duty C solenoid which can cause torque bind.

[wtdash]

Check under the hood for the FWD fuse on the passenger side (on Legacy's @ least). If there's a fuse in, there should also be a 'FWD' lit on the dash. The fuse puts the car in FWD-only mode....should be no need to remove the driveshaft.

I'd bet the tranny's AWD isn't 100% functional.

[Buffman]

Check under the hood for the FWD fuse on the passenger side (on Legacy's @ least). If there's a fuse in, there should also be a 'FWD' lit on the dash. The fuse puts the car in FWD-only mode....should be no need to remove the driveshaft.

I'd bet the tranny's AWD isn't 100% functional.

I thought I've read, that doing that FWD FUSE is for testing purposes/emergency purposes only, and driving with it in for extended periods, is very hard on tranmission center diff.

[07Evolved]

thank you very much for the tips guys....i will check on the fuse. i think the guy is blabbing about the duty c solenoid too.

i have read other threads too about it might also be as easy as changing the trans and rear diff oil if there is problem such as the torque bind and/or the duty c solenoid.

[93forestpearl]

The FWD fuse tells the TCU to send full duty cycle to the Duty C solenoid. The TCU already does this when the front wheels are not slipping.


The TCU uses two speed sensors to adjust the pulse width to the Duty C solenoid, which controls the pressure to the transfer clutch. If the front wheels slip, the TCU compares this speed signal the speed signal from the rear, and adjusts the pressure to the transfer clutch appropriately. Subaru automatics operate with the Duty C solenoid bypassing the transfer clutch pressure until conditions determine otherwise.



The previous owner may have had some torque bind from a failed Duty C solenoid, hence why he would remove the driveshaft. The fuel economy is not going to improve from removing the drive shaft since you are still turning a rear diff, axles, and what not.

[07Evolved]

thank you for the tips forestpearl! so, what should I do to determine if it is in fact the duty c solenoid? should i try the fuse trick?

i have read to see if the "power light" blinks 16 to 17 times to determine it is a bad duty c solenoid, do the FWD fuse trick, etc.

if it is the duty c solenoid that needs to be replaced, how much is it and how tough is it to install? i tried to find a write up on it but couldn't find anything.

[entirelyturbo]

Yeah, chances are very good that the AWD system is screwed up and he's coming up with as much BS as he can.

I'd suspect the clutch pack itself just as much as the Duty C solenoid. If they did stuff like ignore tire rotations or replace only 2 tires at a time, the pack itself might be ruined, which would also cause torque bind.

You have to pull the transfer case off the rear of the transmission to do either. If you do everything, parts are about $250, but it's decently labor-intensive, so having someone do it would run about a grand.

[07Evolved]

Thank you all very much for the info...I will pass this along to my buddy.