PDA

View Full Version : AWD to FWD fuse for BK



devmaster
05-29-2007, 04:34 PM
now that it is summer and i really have no use for AWD except for the occasional fun on a dirt road, and wasting my gas. I was reading the owners manual, and i came across a page that said that if you put a 15v fuse in the slot in the diff fuse on the left part of the firewall. it would be put in FWD mode. I guess for emissions testing testing and dyno runs.

Has anyone done this?


and are there any good results, like loss of some of the parasitic loss from the AWD system or better fuel mileage? :roll:

Bdubs
05-29-2007, 04:46 PM
You really shouldn't disable the AWD for regular driving.
The car was designed as full time AWD, there are no benefits to making it run 2wd.

theboyo19
05-29-2007, 06:53 PM
the kid that owned my car before me did that too.. he didnt see any improvement..
i run awd all the time
correct me if im wrong but i think if you get a flat on a suby u have to put the spare on the back and put in the fwd fuse? thats what ive herd ..

deadlydave
05-29-2007, 06:55 PM
You're supposed to put in the fuse if the car is getting towed by a non-flatbed, so the rear wheels roll freely instead of still being linked to the fronts.

ivwarrior
05-29-2007, 07:16 PM
You most likely won't see any improvement in mileage, and if you do, it'll be tiny. Think about it, all the AWD parts are still there, so you're not saving weight, and the stuff is still turning, so you're not saving anything there, either. Now, pull the transmission and the rest of the AWD hardware and replace with the necessary stuff from a early 90's FWD Suby, and MAYBE you'll get a 1-2 MPG increase.

Bdubs
05-29-2007, 07:51 PM
FYI, Even though it says in the manual that its for towing, don't ever have the car towed any other way than on a flatbed.
Its not worth taking a chance of destroying any drivetrain parts.

tekkitan
05-29-2007, 08:42 PM
FYI, Even though it says in the manual that its for towing, don't ever have the car towed any other way than on a flatbed.
Its not worth taking a chance of destroying any drivetrain parts.

I agree but sometimes there may be no other choice.

Yeah I wouldn't recommend driving with the FWD fuse in. You'll still have all the weight of the AWD parts and on top of that will lose power on the road dragging all that dead weight :)

ivwarrior
05-29-2007, 09:06 PM
FYI, Even though it says in the manual that its for towing, don't ever have the car towed any other way than on a flatbed.
Its not worth taking a chance of destroying any drivetrain parts.

Doesn't have to be on a flat-bed. With a regular tow truck, they can put dollies under the rear wheels to have them off the ground, too.

Christopher Marks
05-29-2007, 10:14 PM
correct me if im wrong but i think if you get a flat on a suby u have to put the spare on the back and put in the fwd fuse? thats what ive herd ..

As long as you're running OEM sized tires, the car has a full size spare.

Wiscon_Mark
05-30-2007, 12:45 AM
Chris Marks beat me to it - that's why I'm not even lugging the spare right now - I can't use it safely as I don't have OEM tires in...

badbasser98
05-30-2007, 08:30 AM
In regards to the OP, I would not drive the car with the FWD fuse in place. As many have stated it is only meant for towing the vehicle with the rear wheels on the ground. I, however, would not even let this happen just for the sake of confusion that might happen. If there is a problem where you need to have the car 'towed' I would make sure the people who do it use a flatbed no matter what. All they need to do is forget that $0.10 fuse and they are going to bake your DutyC.

Sure, there are people that think they are saving gas by using the FWD fuse and driving the car, others will swear they have more power... The fact is the car was not meant to be driven this way and will eventually be detrimental to the performance of the car. Any gains, if any are seen, will be minimal at best and not worth the possible damage to your car. Bottom line, leave it as is (in AWD) and be happy. If you aren't, get a different car...


As long as you're running OEM sized tires, the car has a full size spare.
Most of the lower trim models only had the dummy (donut) spare, not a full size. Though it was an option from the factory.

backpack09
05-30-2007, 08:45 AM
but the donut is the same diameter as stock wheels/tires, making it a "full size" spaire

devmaster
05-30-2007, 09:09 AM
my guess was that in the dif there was some electro-magentic clutch that disengauged when you put in the fuse.. but i am not sure.

..well i guess all i need is to squeeze some more power out of my ej22, now to feel some more power.

Wiscon_Mark
05-30-2007, 10:24 AM
Btw- you have a BK, not a BG.

devmaster
05-30-2007, 01:52 PM
Btw- you have a BK, not a BG.
what is the difference? Whats the BG then?

Wiscon_Mark
05-30-2007, 03:03 PM
BG has a taller roofline. The only BG in the USDM was the 96-99 Outback, the rest were BKs.

People so typically call it a BG because most of the wagon models (if not all) in Japan are BGs.

badbasser98
05-30-2007, 04:31 PM
but the donut is the same diameter as stock wheels/tires, making it a "full size" spaire
true I guess... I always refered to a full size spare as same tire size as the car runs normally. Meaning diameter, width, and sidewall height.

devmaster
05-30-2007, 06:27 PM
BG has a taller roofline. The only BG in the USDM was the 96-99 Outback, the rest were BKs.

People so typically call it a BG because most of the wagon models (if not all) in Japan are BGs.
thanks that clarifies it

Reason
05-31-2007, 08:23 AM
I have 2 "donuts", one from my 97 GT and another from my 92 SS. Neither are the same diameter of the stock wheels. As for towing every time I called for a tow I requested a flatbed. I had the FWD fuse in for a week just to see if I noticed anything. I don't keep track of gas mileage so I don't know if there's a difference (but someone should bite the bullet :smile: ). The car did seem a bit more peppy, but the feel of it was different and I didn't like it.

backpack09
05-31-2007, 08:49 AM
I have 2 "donuts", one from my 97 GT and another from my 92 SS. Neither are the same diameter of the stock wheels. As for towing every time I called for a tow I requested a flatbed. I had the FWD fuse in for a week just to see if I noticed anything. I don't keep track of gas mileage so I don't know if there's a difference (but someone should bite the bullet :smile: ). The car did seem a bit more peppy, but the feel of it was different and I didn't like it.

I stand corrected. :oops:

Reason
05-31-2007, 09:03 AM
Excuse me, I still haven't slept yet. I meant they ARE the same diameter, but aren't a FULL size spare. It's a donut but stock diameter. Am I making any sense right now??

devmaster
05-31-2007, 09:57 AM
I have 2 "donuts", one from my 97 GT and another from my 92 SS. Neither are the same diameter of the stock wheels. As for towing every time I called for a tow I requested a flatbed. I had the FWD fuse in for a week just to see if I noticed anything. I don't keep track of gas mileage so I don't know if there's a difference (but someone should bite the bullet :smile: ). The car did seem a bit more peppy, but the feel of it was different and I didn't like it.

ya, i will try it out next week.. i have to travel like 400 miles this weekend so im not going to chance it. but ill keep you posted

backpack09
05-31-2007, 11:47 AM
Excuse me, I still haven't slept yet. I meant they ARE the same diameter, but aren't a FULL size spare. It's a donut but stock diameter. Am I making any sense right now??

Nah go back to bed. :lol:

Wiscon_Mark
05-31-2007, 11:58 AM
Yeah, I was gonna say, Shane, what are you smoking?

Sarra
06-01-2007, 02:48 AM
4EAT's typically run a 90/10 f/r torque split in D anyway. If there was any benefit to using the FWD fuse, then the drivedrain already uses it during normal driving anyway.

I popped the FWD fuse into my mom's outback, and I still couldn't get it to do burnouts. D: Then again, it had studded snow tires on it when I tried that...

Perdue
06-01-2007, 09:13 AM
Sarra is right. The automatic transmissions have a 90-10 front-rear torque split. I've heard many different theories on how the FWD fuse works, one being that it allows the center diff to slip somehow...slippage=heat though. It's not something you're going to see a large gain off of, as your car is still moving the rest of the AWD parts, reguardless of if you're in FWD or AWD. Same theory as my truck going from 2wd to 4wd...the stuff is still spinning and moving whether it's in 4wd or not.

Huffer
06-01-2007, 09:34 AM
There's no theory to the FWD fuse.
The fuse tells the TCU that it should disengage the DutyC solenoid so that the rear wheels have no drive being sent to them.

devmaster
06-03-2007, 12:24 PM
i did it Thursday.. it was as disappointing as i expected. it made the car feel like a low power FWD car. along with all the downfalls of FWD. when i first stepped on it i got huge bump steer. the engine feels like it has a little bit more pull. although i got allot more torque steer than normal.
the trans felt more "slushy", that could be attributed to the 95 degree temps outside.

However i did get it to do a burnout. a very lame one at that.

i drove about 30 mi. then i went home and took the fuse out.

so overall dont wast your time. if u want FWD get a jetta or somthing.

Sarra
06-03-2007, 03:38 PM
The 4EAT uses a mechanical LSD. Therefore, it's possible to completely disconnect it.

Wiscon_Mark
06-03-2007, 11:51 PM
I don't think it has a LSD at all...

hink01wag
07-15-2009, 07:33 PM
so i have a question regarding this post. my town doesn't have a 4 wheel dyno so i have to put it on a 2wheel one. can i put the fuse in or take it out witch ever to get my car to only run fwd? i have a 01 leg

decke48
07-15-2009, 08:17 PM
one the local dyno probally wont let you do it because its an awd car, even though it can be run fwd. safety issues
two it wont give you an acurate reading

AWDisGREAT
07-27-2009, 06:52 AM
Speaking of the FWD fuse, I set mine up so that I can flip it from FWD to AWD & back again & I do notice that the gas needle moves a LOT less than it did before. Also, I could NOT stop peeling the tires every time I pressed the pedal (this annoyed the HELL outta' me) & the car shifts normally (actually, the shifts seem to happen sooner than when it's in AWD). I haven't gotten any problems yet & I don't expect there will be any (I'm guessing I'm pretty lucky I put Synthetic Differential Fluid on both ends (but there's always that chance that something will go wrong).

gina daniels
09-19-2010, 07:10 PM
What size fuse do I use for FWD?

cmilligan724
09-19-2010, 08:28 PM
ok i did this and i just pulled the a/c fuse and drove like that. My wagon would rev up and then shut off due to the trans sensing to much tension in the gearing. i think it was to much on my motor. no burn outs for me :-(

Subaruandy
11-25-2010, 12:25 AM
Can someone quote from a Subaru manual exactly what it says about use of this fuse? I've played with it and I've seen the changes but I can't find anything about it in my owner's manual.

I've got a 96 Legacy which had the shudder problem; see
viewtopic.php?f=3&t=19897&hilit=duty+solenoid (http://www.sl-i.net/FORUM/viewtopic.php?f=3&t=19897&hilit=duty+solenoid)

I think it's fixed now that I had the AT flushed and filled with synthetic fluid and added Lubegard ATF Protectant. I say I "think" it's fixed because I only have 100 miles on it since the new fluid was added. But I'm pretty sure.

Anyway, I'd like to get some clarification on the use of the FWD fuse since that's part of the diagnosis of the problem. (See the above referenced discussion.)

Andy

jey
11-25-2010, 05:51 AM
Owner's manual doesn't have the detail on the operation of the FWD fuse, especially in reference to diagnosis. It only references it with regards to using the temporary spare tire (page 8-12):

"(If your vehicle is AWD with automatic transmission) Before driving your vehicle with temporary spare tire, put a spare fuse inside the FWD connector located in the engine compartment and confirm that the front-wheel drive warning light comes on. The all wheel drive capability of the vehicle has now been deactivated. After re-installing the conventional tire, remove the spare fuse from the FWD connector in order to reactivate all wheel drive."

Subaruandy
11-25-2010, 04:16 PM
You said:

"Owner's manual doesn't have the detail on the operation of the FWD fuse, especially in reference to diagnosis. It only references it with regards to using the temporary spare tire"

Ah hah! So they just don't want the AWD system (clutches or whatever) trying to make all the wheels go the same speed when you're using a donut which probably turns faster than the other 3.

That makes sense.

It would also seem to indicate that running with that fuse all the time might be OK. Or am I reading too much into this?

Andy

Kiwi GT
11-25-2010, 05:51 PM
It doesn't completely disconnect drive to the rear wheels. It drops it down to 5% rear, 95% front. If it is towed with the rear wheels still on the ground, you will wear out the centre coupling clutch pack. The 4EAT has a full mechanical connection to the front wheels, but the rears are varied by the duty solenoid C (transfer solenoid) to transfer between 5% (open) and 50% (locked) of the drive to the rear wheels.

You will not save any gas by running it in FWD mode as all parts are still rotating as they were in 4WD mode. You will only succeed in damaging the centre coupling clutch pack.