FWD fuse

[92 SVX]

Ok got time to go over this again, I have all wheels off the ground, I put the fuse in and put the car in gear and using a 2x6 stop the left rear tire, it takes some effort and the other side just keeps going, a little faster I would say. I go to the other side and try to stop this tire, its almost impossible it pulls the board out of my hand twice. when I do get it stopped the other side goes faster. I think there is still power going to the rear.
I have been noticing what appears to be cv joint problems recently front right seems to chatter a bit when turning right. and the left lower ball joint is bad I dont think either of those have anything to do with the fwd fuse but I mention them because when turning sharp I do not seem to have front to rear bind.

[NiftySVX]

Trevor brings up some good points, and I would like to add to them as there was a time in my life when I could fill a box with faulty duty C solenoids.

First, on a brand new transmission there will be enough drag when FWD is engaged that the rear wheels turn slowly, but not as fast as the front. Grabbing hold of one tire should make them both stop as this light drag is not enough to overcome LSdifferential action, even though at this stage in the game most of the SVX clutch packs in the rear diffs are shot. If the trans is used it will not normally turn the rear wheels at all when in FWD and all 4 are off the ground, assuming the car is in D and just rolling along at idle. Even with a properly working duty C this may happen, but as soon as you touch the gas pedal and come off idle the solenoid will increase duty and lock the clutch, causing the front output to rotate at the same as the rear output (when in AWD AUTO)

Now, The easiest way to test a sol C. is by my own personal (ok It was taught to me but i'm taking credit) duty C test, and it requires no tools. Park the car over some concrete or some sound reflecting surface in a quiet area. Then, turn the ignition to ON with the shift in P or N. (radio&climate OFF)but do not start the engine. In the quiet area, slide the shifter to any moving position. this action will cause a very distinct buzzing noise that you can hear if you lean your head out the open door near the undercarriage. It should sound like a healthy bee flying (loudly) in the tailshaft of the transmission. This noise should continue as long as the shifter is in a moving range. If there is no noise, if there is a single click, or if there is a bzzzz...zzzz..zzzzz....................zz......... .(nothing) then you've got a bad C soleniod.

Another possibility you have is that the front and rear final ratios are not the same and the clutch is fighting this action.

Now, you may have destroyed the FWD circuit in the TCU if you applied power to the lead. ALL switching side circuits on real cars (japanese) and not crappy GM or FORD use ground side switching because it does not cause arcing in the switches. This may be why your FWD light will not light.

The pinched wire is also possible though I have not seen this happen, but of course I am always careful with the harness. I suppose a careless person could pinch the wire as it just kinda hangs out in the trans, it's in a pretty open space above the main body.

Hope this helps. I am going to make a Youtube video for the sol. c test this weekend. Many diagnoses have been made using this simple test!



In

[NiftySVX]

Originally Posted by Trevor

The FWD light does not appear to be included within the ignition on test circuit. If it has never come on, the bulb may be faulty.

However, if you are still registering code 24, something is wrong within the solenoid "C" circuit.

You now mention binding, i.e. did not have so much bind. Without you providing full and exact information you can not expect proper assistance. Perhaps you should start again from the beginning.

It is not part of the bulb check on the SVX. If I recall, it isn't on any subaru that had the 'FWD' light.

[92 SVX]

Nice information, I can tell you the solenoid C does not make any sound at all when I turn on the key. The FWD light never lit at any time, one reason I did check the fuse power before I did anything with the fuse I also tried the fuse and found the wheels to be turning. And there was and is definitely power to the rears your theory on the front diff gearing makes sense but I am leaning away from that there is no other problems with bind. I left the fuse out and tried stopping the rear tires and it was actually easier to stop them, though stopping one just caused the other to speed up a little. I physically blocked one rear and used the board to stop the passenger side, I got both to stop, however the passenger front also stopped. could not see the drivers front. and I did not have a helper so I was leary of blocking both rear.

[92 SVX]

Oh as a side note, I checked out the cv shafts I dont have any cracked rubbers though the passenger side is getting weather checked looking but the joints are solid on that side. The drivers side however I have movement of the entire shaft. It is just a little bit and I am wondering if it is because the ball joint is bad.
Could a bad ball joint allow excess movement on the axle end?

[NiftySVX]

The axle moves in and out of the cup on the inner joint, this is because its total length must change as the wheel goes over bumps.

Don't worry about the boots if they are not torn open.

Also, for the duty C test the fwd fuse should not be inserted. In fact, inserting it in a proper system will make the noise stop.

I would still be wary of the mismatched finals. The symptom you are describing are what it would do, I have never seen this happen but have heard stories of it happening from collegues. For some reason, random auto shops that are not dealerships and don't really have any business working on an SVX or any subaru really have a problem understanding that a subaru 4EAT comes in many different flavors.

[92 SVX]

I should have been more clear, there does not appear to be solenoid noise with or without the fwd fuse. I would expect there to be lots of binding in any direction, going straight, turning or backing up if the diff gears were incorrect, not to mention the front and rear speed sensors would be going nuts as the tires would not be spinning at the same speed.
If those points are inaccurate please let me know I have worked with 4WD systems, that use a transfer case and they lock the front and rear together and with different diff ratio's you will not drive far.

[oab_au]

Originally Posted by NiftySVX

snip.
Now, The easiest way to test a sol C. is by my own personal (ok It was taught to me but i'm taking credit) duty C test, and it requires no tools. Park the car over some concrete or some sound reflecting surface in a quiet area. Then, turn the ignition to ON with the shift in P or N. (radio&climate OFF)but do not start the engine. In the quiet area, slide the shifter to any moving position. this action will cause a very distinct buzzing noise that you can hear if you lean your head out the open door near the undercarriage. It should sound like a healthy bee flying (loudly) in the tailshaft of the transmission. This noise should continue as long as the shifter is in a moving range. If there is no noise, if there is a single click, or if there is a bzzzz...zzzz..zzzzz....................zz......... .(nothing) then you've got a bad C soleniod.



In

Hi mate.
You can test the A solenoid at the same time.

Same conditions, key on, engine off, shifter in P,N. There is no sound till you push the pedal down about 25%, you can hear the solenoid getting a signal for low pressure. As you push it down the sound changes as the signal goes to higher pressure. It hits full pressure at about 75% throttle.

Harvey.