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  #1  
Old 12-05-2002, 07:37 AM
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SVX10 SVX10 is offline
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Question Transmission "how to" idea?

Hey everybody. I was just doing a search on transmission stuff (looking for diagnostic procedure), and I found that a transmission problem is often caused by a failed duty solenoid. While it is very easy to do the diagnostic test in the "how to" folder, I think it would be great to have more info there on the duty solenoids in a consolidated location. Could anybody who knows more about the duty solenoids possibly make a list of what each of their functions are, and maybe what could be signs of failure. The list/table could then be put in the "how to" folder For example...

Duty Solenoid A:
Controls blah blah blah

If you experience blah blah blah, you may have a problem.


I wouldn't mind doing it, but I only have internet access at work, and therefore won't have an opportunity to search the posts to fill in the "blah blah blah" blanks. If it's too much trouble, then don't worry about it, but I think it would be a valuable tool for the network.
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Time for my very own long list of mods:
92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler

I don't care if Subaru says it's STI...it will always be STi to me
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  #2  
Old 12-05-2002, 10:17 AM
Green1995SVX
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I can TRY to do that this weekend.

Mike
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  #3  
Old 12-05-2002, 11:11 AM
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Sweet
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Time for my very own long list of mods:
92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler

I don't care if Subaru says it's STI...it will always be STi to me
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  #4  
Old 12-05-2002, 03:31 PM
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I think that's a great idea, Matt.
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  #5  
Old 12-05-2002, 03:43 PM
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  #6  
Old 12-05-2002, 04:15 PM
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Yea...Mike's the shizz cuz he has a sweet SVX and he makes lists for the network. Maybe I'll be a good manager one day...

"I think this list would be great for our organization. I'd do it myself but (fill in excuse)"
"Yes sir. I will do that tonight. I was going to go to my son's birthday party, but I'll work OT."
"Sounds good. Since you're helping the organization, I'll represent the organization and help you by filling in at the party. See you tomorrow."

Yea...no...??? Hmmmm, can't wait to get off work and go wax mah baby!
__________________
Time for my very own long list of mods:
92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler

I don't care if Subaru says it's STI...it will always be STi to me
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  #7  
Old 12-05-2002, 08:26 PM
gl1674 gl1674 is offline
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Duty Solenoid A - controls line pressure. Normally closed (i.e. when disconnected from power). TCU keeps it fully open from
0 to 2000 RPM. At 2001 RPM it applies 50% duty cycle that quickly goes to 0% as throttle position and engine RPM are increased.

This keeps line pressure at 60/80 (forward/reverse) PSI at idle
and increases it to 140+ PSI at 5000rpm. Lower pressure at idle slows down shifts to make them smoothers and improves fuel economy (less energy wasted pumping ATF). Higher pressure accelerates shifts and prevents slipping of clutches when engine develops high power/high torque.

Possible failures -
a) coil short circuit or disconnect (detected by TCU - you get flashing green light when starting engine)

b) mechanical wear of the moving parts that keeps solenoid always open or open much wider than it should be. This is not detected by TCU, the only reliable diag is attaching oil pressure gauge to the test port in transmission.
Worn solenoid A unfortunately this leads to lower line pressure, excessive clutch slippage and dramatically shortens transmission life span (what do you expect if clutches slip at full load - the maximum possible wear).

On my car I saw high/forward or lockup clutches (no way of knowing for sure) slip at >50% throttle if I increased throttle gently to keep the car in lockup. The rpm would jump from 2500 to 2700-3000 but jump back immediately as I released throttle a bit. This was not an unlock of lockup clutch, because TCU does not lock it back immediately - it waits 5 seconds or so.

Duty solenoids are more likely to fail this way than shift solenoids, because they work much more (cycle 60 times per sec compared to one cycle per gear shift).
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  #8  
Old 02-02-2003, 07:28 AM
Ticallion
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AHH!! jesus!

you've just described my tranny problem. When accelerating slowly when the tranny is nice and hot after about 20 minutes of driving, from 1st to 2nd, it slips and the rpm jumps about 1000, then the car shifts and it jolts the car forward.

Plus, it takes a bit longer than most cars to switch gears with the shifter.

How much does a Duty Solenoid A cost? How much is it to replace? Can you do it with the tranny in the car?

AHHHHHHHHHHHHHH!
*slowly crying on the inside*

-Ross
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  #9  
Old 02-02-2003, 11:17 AM
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You can replace all the solenoids without removing the tranny. Not sure what the prices are but you can check the usual sources.

Let us know if it works.

Quote:
Originally posted by Ticallion
[BHow much does a Duty Solenoid A cost? How much is it to replace? Can you do it with the tranny in the car?

AHHHHHHHHHHHHHH!
*slowly crying on the inside*

-Ross [/B]
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