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  #1  
Old 01-16-2004, 09:49 AM
Jack
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Duty Solenoid C

96 SVX: I periodically get the 16 blinking lights and then run the diagnostic and get code 24 - duty solenoid C. In reading old posts on this subject, most indicate a sympton of binding in turns. I don't know why locking into awd should produce this symptom. This should be a problem between left and right axles, not front and rear, I would think. Anyway, I get no symptoms at all. Any problem with just continuing to drive it? Sometimes, when I get the 16 blinks, I restart it a few times until it doesn't blink and then drive. Is there anyway to actually know when the car is actually in the awd drive mode with I assume a 50/50 split of power. I know some awd cars vary the power to each corner. In the SVX does it just vary the power between front and rear? The car has just a little over 100K on it and this is the first sign of a transmission problem. The car is completely stock. I have not installed an external cooler or filters. I do have the transmission flushed about every 30k and use RedLine fluid. Have had my share of wheel bearing problems - 5 on the left rear and 2 on the right rear replacements. Only replaced the rotors once. Have had the car since new.
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Old 01-16-2004, 12:14 PM
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Re: Duty Solenoid C

Quote:
Originally posted by Jack
96 SVX: I periodically get the 16 blinking lights and then run the diagnostic and get code 24 - duty solenoid C. In reading old posts on this subject, most indicate a sympton of binding in turns. I don't know why locking into awd should produce this symptom. This should be a problem between left and right axles, not front and rear, I would think. Anyway, I get no symptoms at all. Any problem with just continuing to drive it? Sometimes, when I get the 16 blinks, I restart it a few times until it doesn't blink and then drive. Is there anyway to actually know when the car is actually in the awd drive mode with I assume a 50/50 split of power. I know some awd cars vary the power to each corner. In the SVX does it just vary the power between front and rear? The car has just a little over 100K on it and this is the first sign of a transmission problem. The car is completely stock. I have not installed an external cooler or filters. I do have the transmission flushed about every 30k and use RedLine fluid. Have had my share of wheel bearing problems - 5 on the left rear and 2 on the right rear replacements. Only replaced the rotors once. Have had the car since new.

Jack,
One way to test for AWD-ness is to find a place where you can put your front wheels on the grass and your rear wheels on pavement, then, punch it (not floor it, just punch it a little). If you move immediately, you're golden. If your front wheels spin, you're looking for repairs.

The split on the SVX (I believe) is 90/10 up to 50/50. Transfer is from front to rear. The LSD takes up the slack of the "per wheel application" ratio found in later model cars.

Sounds like, perhaps your Sol C is "sticking." Perhaps sa good tranny treatment could loosen it up a bit. Otherwise, it'll cost you about a grand to have it replaced at a reputable shop.
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  #3  
Old 01-16-2004, 12:32 PM
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Thanks Randy, but I am not sure I understand the grass thing. As I understand it, if the C solenoid goes bad, then the car is in 50/50 power distribution all the time. So if that is the case, it would seem unlikely that the front tires would spin. What I was wondering was even tho the light is coming on, maybe in fact the transmission is still in the 90/10 mode rather than the 50/50 mode and is there any way to tell? I will go ahead and try the grass thing anyway and let you know how it goes. The estimate I got was $1k to replace the solenoid assuming nothing else is wrong, so sounds like you are right on about that.// Jack
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Old 01-16-2004, 12:46 PM
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Quote:
Originally posted by Jack
Thanks Randy, but I am not sure I understand the grass thing. As I understand it, if the C solenoid goes bad, then the car is in 50/50 power distribution all the time. So if that is the case, it would seem unlikely that the front tires would spin. What I was wondering was even tho the light is coming on, maybe in fact the transmission is still in the 90/10 mode rather than the 50/50 mode and is there any way to tell? I will go ahead and try the grass thing anyway and let you know how it goes. The estimate I got was $1k to replace the solenoid assuming nothing else is wrong, so sounds like you are right on about that.// Jack

Depends on whether the solenoid quit when it was open, or when it was closed.

When mine was stuck in full-time AWD, I could "feel" it. It's a totally unmistakable feeling when turning sharply (especially in reverse). You can just feel all four wheels pulling. I know it sounds weird, but that was MY experience. It's not so much a "binding" as it is a "knowing" that all four wheels are working at equal levels.

You can try inserting the FWD fuse to see if there is any change in the characteristics of the car with the fuse in and the fuse out.

My problem turned out to be the TCU. If you put the fuse in, and it will not *stay* in FWD mode, then, your problem is more than likely a TCU problem too. Interestingly, I got no Power Light, when my TCU was going bad.
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Old 01-16-2004, 01:08 PM
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I will put in the fuse and then try the grass thing. Thanks for the idea.
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  #6  
Old 01-16-2004, 01:57 PM
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Quote:
Originally posted by Jack
I will put in the fuse and then try the grass thing. Thanks for the idea.
My pleasure.
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  #7  
Old 01-16-2004, 02:47 PM
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Quote:
Originally posted by Jack
I will put in the fuse and then try the grass thing. Thanks for the idea.
If you put in the fuse and then try the grass thing, your front wheels will spin even if there's nothing wrong with the car. Putting a fuse in the 'FWD' slot effectively makes the car forget about the rear half of the drivetrain and no pressure is applied to the transfer clutch.

It sounds like you're a little fuzzy on how the whole thing works. I'll give you a little explanation.

Instead of having a center differential or viscous coupling between the front and back halves of the drivetrain, the SVX has a multiplate clutch. When the TCU senses a difference in the signal from the two speed sensors in the transmission (one for the front and one for the rear) that suggests the fronts are spinning, it applies pressure to the transfer clutch. It does this by using duty solenoid C. Since it's a solenoid and simply on/off, it applies more or less pressure (more or less torque to the rear) by fluttering on and off at different frequencies. This allows more or less hydraulic fluid to act on the piston that's pushing the transfer clutch together.

The difference between the signals received from the two speed sensors doesn't just happen on a slippery surface. When you turn, the front and rear wheels take different paths and therefore spin at different speeds. So even on a dry surface there's a difference between the signals from the front and rear wheels and the TCU has to operate duty solenoid C to compensate. If duty solenoid C doesn't work right, the transfer clutch binds up. This will tear up your transfer clutch pretty quickly. Eventually, the clutch will be totally worn and the binding will go away - but so will your AWD. Your car will effectively be FWD because duty solenoid C doesn't work and there's not enough clutch material left for it to work with anyway.

Randy's recommended procedure works because you're putting the front wheels on a surface where they will slip and the rears on a surface where they won't. If your car is working properly, the fronts will barely slip before the rears push you forward. Now, the important thing to note here is that the fronts really shouldn't slip much at all. I've driven much less elegant MPT clutch-operated AWD cars, and they slip a considerable amount before the rears help out. Not so with the SVX - it should be nearly instantaneous.

But I think that his recommendation is better for diagnosing a bad transfer clutch - because the TCU can't tell you that it's worn and unable to use it. It can tell you about electrical problems like duty solenoid C. If it gives you that code, then no extra diagnosis is required and you just need to replace it. The only other option is to drive around with that FWD fuse in until you do fix it, because (as I explained) you're going to tear up your transfer clutch if you don't.

Whew, that was longer than I meant it to be. Anybody feel free to point out any mistakes I made.

Anyway, my wife's Legacy has a bad duty solenoid C. I will fix it, but in the meantime I put in the FWD fuse so it doesn't tear up the transfer clutch.

PS My recommendations assume that the TCU is good. It sounds like yours is working fine, which is why I made that asumption.
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Old 01-16-2004, 03:08 PM
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As you correctly surmised, I am a little more than fuzzy about how this all works. Your explanation helps. I had asked my mechanic about putting the fuse in and driving it that way until it was repaired, but he said that if duty solenoid C was bad that the fuse would not help - that the car would stay in a 50/50 power split even with the fuse in. Randy's procedure (with the fuse in) can certainly verify if that is happening or not.
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Old 01-16-2004, 03:09 PM
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Certainly - try it. Let us know what you find. I predict that once you put a fuse in that slot, your binding will go away.
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Old 01-16-2004, 03:21 PM
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Quote:
Originally posted by Jack
As you correctly surmised, I am a little more than fuzzy about how this all works. Your explanation helps. I had asked my mechanic about putting the fuse in and driving it that way until it was repaired, but he said that if duty solenoid C was bad that the fuse would not help - that the car would stay in a 50/50 power split even with the fuse in. Randy's procedure (with the fuse in) can certainly verify if that is happening or not.

I am currently driving with the FWD fuse in one of my SVXes. I accidently chirped the front wheels pulling away from a stoplight today. 'Nuff said.

PS: The tires NEVER chirp with the fuse in. She's 100% FWD.
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  #11  
Old 02-11-2004, 03:35 PM
Jack
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I have experimented with this over the last several weeks. I do not always get the blinking light when I start the car. If I do get the blinking light it appears to be stuck in all time awd. I can put the front wheels on any slippery surface and the backs on good surface and I get no spin at all from the fronts. I put in the fuse and sometimes the fwd light comes on and some times it does not. When it comes on it is definitely in fwd. I can easily spin the fronts even on dry surfaces. Once the fwd light came on, but after driving for about 50 miles the light went out and sure enough I was back in awd. Anyway I have been driving it for a few days now with the fuse in and it has stayed in fwd so I guess I will continue that until I am ready to replace the solenoid. Thanks for all the advice. Will let you know if anything new develops.
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Old 02-11-2004, 04:50 PM
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Driving with the fuse in.

While you are driving with the FWD fuse in, refrain from spinning the front wheels, as it can put shock loadings on the front differential, that can break it.

Harvey.
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  #13  
Old 02-12-2004, 07:11 AM
Jack
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Thanks for the advice. I will try to keep those front wheels from spinning. This is a whole different car in fwd than it is in awd with all that torque steer and those front wheels wanting to spin particularly taking off from rest and making a a 90 degree turn.
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Old 02-15-2004, 10:57 AM
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Hi Jack,

I had the same problem on my car. If your getting Torque steer something is wrong and as Harvey said, it'snot good for the front end. Take it easy until you get the RWD working correctly.
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Old 02-16-2004, 06:46 AM
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Hi folks.....have you thought of something regarding duty-sol.C ?

How in the earth could the transfer clutch disengage if not d.s.C is working ?

The way I see it, the d.s.C HAS to OPEN to disengage rwd...., and d.s.C's function is that if no power is applied to it, it is closed....!

...or...??


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