I see this is your first forum post, so welcome!

The fuse is NOT removed, but is installed! The fuse acts like a "switch" to enable FWD ► fuse installed or disable FWD & enable AWD ► fuse removed.

From the Owner's Manual:

All AWD AT models - Before driving your vehicle with the temporary spare tire, put a spare fuse inside the FWD connector in the main fuse box located in the engine compartment and confirm that the Front-wheel drive warning light "AWD" in the combination meter comes on. The all wheel drive capability of the vehicle has now deactivated. After re-installing the conventional tire, remove the spare fuse from the FWD connector in order to reactivate all wheel drive.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]

 

Note that this applies only to Automatic Transmission cars. AWD cannot be disabled on Manual Transmission, as this is not required for the donut spare situation described in the Owners Manual.

 

Bruce,

The instructions I posted are from my '07 owner's manual, which comes with a compact spare. I also looked in our '03 owner's manual, which comes with a full size spare & there are no instructions for disabling AWD. However, the image I posted is from the '03 owner's manual.

As I read it, for AT transmission:

• Compact spare use = must disable AWD.
• Full size spare use = not required to disable AWD.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]

 

Yup. I see that you highlighted AT there. So I guess it's not just donut but all AT.

The OP hasn't posted transmission type in his profile, so we're not sure which variety he has.

 

Thanks for the feedback, I removed the "A" fuse based on the diagram above and it re-enabled the AWD (and the AWD light is no longer displayed on the dashboard). With the fuse out, the Knocking, binding and torqueing has started again, but I want it in AWD with winter here. A mechanic told me to add some limited slip additive. At Advance Auto I bought this "Trans-X Posi-Trac Limited Slip Gear Oil Additive". It's supposed to help with the knocking and binding while the AWD is engaged. It says to add the product to the differential. Does this sound right? If this is right, I would just add it, not plan to drain the differential first. And would I add it to the differential gear oil level gauge? Thanks again, I appreciate the insight here. Tom

 

Keep in mind forcing the AWD to FWD is for temporary use. Take a look at this thread: AT Forester - FWD mode FTW?

Take a look at my quick Google forum custom search results for torque bind to see if anything there answers your questions.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]

 

Note of follow-up even though this is a very old thread. One Foz owner (early SG model) on a Facebook chat reported having gone through two transmissions (4EAT) which appears to be related to extended use of the FWD fuse when in on road conditions. He reported that both times the pinion on the differential was chewed to heck, after about 6000 miles. He also reported running oversized tires and significant lift. So, the lesson learned appears to be, only run the FWD fuse if needed to temporarily get home or to a shop on a small spare, mounted to one of the rear wheel positions. Otherwise, run AWD. Oversized tires were probably a significant contributing factor. Wear acceleration issues are often not linear, meaning that there are thresholds where a little more stress moves some bit of metal into an accelerated stress range and stuff breaks a lot sooner.

 

After my post above I remembered that Subaru Transmissions (the 5MT at least) are often used in VW buses as 2WD options will all of the power going through the single pinion/diff. This is a little different from just puling the fuse, but the failure I noted above is a pinion failure, not a failure in the center differential. The pinions on the 5MT and 4EAT are not going to be a much different, and I can't imagine why the metallurgy on one would be different from the other. The 4EAT in the forester usually gets a 4.444 ring/pinion, while the 5MT gets a 4.111 ring/pinion. I've heard that the 4.111 is inherently strong because of the tooth sizes, but this should account for a rather small difference in strength.

So, for the fellow with chewed up pinions... seems like there is something else going on, or increasing tire size has a very non-linear increase in stress on the pinion.