Fuse for switching from AWD to Front wheel.

[Mary32]

So I have a 2002 Impreza. The back half of the tranny is having issues so I put in the fuse that disengages the rear wheels in driving. Then my electrical engineer brother got clever and hooked up a switch in the cap the sets the fuse on and off for me.

    So the question is when using the fuse to go from AWD to FrontWD do I need to turn my car off, or is putting it in neutral enough? Thanks much!

[Bushwick]

I've done it in Park with engine idling. I wouldn't flip it while moving though as it might cause some initial slipping and/or wear, but that's just guess.

[Fairtax4me]

Worst case the AT temp light will turn on and set a code. Restart the car and the light will turn off. 

 

Flip to your hearts content. Rolling or stopped, front and rear output shafts from the trans will be moving the same speed regardless, unless you're spinning the front tires. If the tires are spinning hit the brake and let them stop before flipping the switch. 

[Mary32]

Yall are the best!

[idosubaru]

fip it at will - don't even think about it.

 

what you may need to think about is not ever driving on pavement/dry pavement with the 4WD "on". don't forget it and leave it on or have the switch somewhere where a pet or person can accidentally bump it (both of which i've seen happen)

i've wired them before such that they will also light a light in the cabin so you're reminded that it's on.

 

as for when to flip the switch, it doesn't matter.

when the car is running and driving essentially the TCU is constantly adjusting the application of it as well.

 

one could argue that the switch is safer for the transmission than the TCU control - which would allow more slip so to speak - kind of like riding a clutch. the switch will be instantaneous loading of the clutches and never using the clutches for large amounts of mileage (when it's off). a pointless point - except to say that overtly granular technical banter can sound good but not really add up to anything practical.

 

the best data point is that people have been doing this for decades now, i've done it a bunch of times.

 

if this is the initial onset of torque bind you might even repair the vehicle with a fluid flush or 3 drain and refills. that's freed almost every one i've encountered so far when they initially start failing, car sat for awhile, or were moderately binding. the fresh fluid aids the clutches.

Edited March 3, 2016 by grossgary

[golucky66]

I have a switch in my car (96' impreza) that does the exact same thing. I've turned FWD on while driving down the road at 40 mph. But mostly use it to have a bit more fun in the snow.

Wouldn't worry too much about it... Unless you're switching it every 10 seconds for 50k.

[Bushwick]

Has Subaru ever incorporated an actual switch in newer US models? I imagine it's cheaper to have a little interrupt fuse holder vs. wiring into the cabin and adding a legit toggle switch, but it seems like a better selling point to have a toggle.

[johnceggleston]

the FWD fuse does nothing mechanical,

it activates the duty c solenoid which then de-activates the transfer clutch.

this eliminates the power to the rear, making the car Front Wheel Drive.

 

 

this is not the same as installing a switch that ''locks'' the front nand rear wheels together like a 4WD truck with locked hubs.

[Mary32]

Thanks for the info.

[ThosL]

Does having the fuse in the fwd slot help with mismatched tires while an owner is working on remedying the situation?  Thanks!

[matt167]

Does having the fuse in the fwd slot help with mismatched tires while an owner is working on remedying the situation?  Thanks!

 

that's what it's there for.. The spare, or smaller tires should be put on the rear and the fuse placed for FWD only

[ThosL]

OK, so I will keep it in there in the interim, a rear differential fix is expensive.

[Fairtax4me]

Has Subaru ever incorporated an actual switch in newer US models? I imagine it's cheaper to have a little interrupt fuse holder vs. wiring into the cabin and adding a legit toggle switch, but it seems like a better selling point to have a toggle.

Besides the extra cost, it would be a useless feature for the average Subaru driver. Useless in that it would probably never get used, and if it did it would probably be used incorrectly.

 

Adding in a switch creates a situation where damage can occur if the switch is flipped at the wrong time, Warranty claims that may be denied, and lower customer satisfaction ratings.

Maybe they add in some coding in the TCU to prevent sudden engagement of the transfer clutches of the switch is flipped at an improper time. But that again adds cost.

[ThosL]

I had one of the Subarus, I forget which years with the four wheel drive option build into two wheel drive vehicles; also a low and high gear lever.  I prefer manual to automatic.