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Hi All, (1995 Seville STS Northstar) Been having issues with my transmission, sometimes it shifts real hard, sometimes it slips, sometimes check engine light comes on and the car hardly moves, especially in reverse. Brought it ot a tranny shop, they reset the computer and good as new for a month or so. So now when i have any issue i just disconnect the battery for a few hours and it will reset the tranny. but now it is much more frequent and not acceptable to me any longer.

Anybody have any ideas what the issue can be to fix it once and for all, car has 130K miles on it

Thanks in Advance

Scott

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You need to check for codes and post them here. Hard to diagnose without the codes

How is the fluid level?

Shifting hard was a symptom of the ISS sensor on my 96

Let us know what you find in codes and fluid level and color

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Don't know if these rae the actual codes, but by pressing OFF and Temp Up simultanously i get this............CODE PO52 HISTORY, CODE P076 HISTORY, CODE P109 HISTORY, CODE 086 CURRENT, AD12 CURRENT, S036 HISTORY, PCM?, NO SIR CODES, NO TCS CODES

DON'T Know if this means anything or not, fluid level is good

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Hmmm, did you replace this transmission at any point? This is an STS, if it was not replaced with an STS tranny, you can get the gear ratio problem (just a guess)

P086 (E086) ................... Undefined Gear Ratio (Transmission Pressure Control)

See this thread

http://caddyinfo.ipbhost.com/index.php?showtopic=41893&st=0&p=206586&hl=p086entry206586

and this

http://caddyinfo.ipbhost.com/index.php?showtopic=30532&st=15&p=171871&hl=p086entry171871

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Ill check the manual later and see what I can find out. If you are lucky maybe its a bad pressure solenoid in the side pan

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Looking at this further it is looking like a pressure solenoid, this code is in history.

P076 (E076) ......................................... Transmission Pressuse Solenoid<<<<<<<

P109 (E109) ....... Keep Alive Memory (KAM) Reset/PCM has lost primary battery power (not a big deal battery must have been disconnected)

A012 ........................................... Low Side Temperature Sensor Circuit (related to your AC)

A tranny shop or a dealer may be able to test the pressure solenoid or it may even be possible to energize it via the OBD1 overrides... Ill see what the manual states, I have one for a 94 that is also OBD1

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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See this thread, its by MAC, I sent him and email to see what he did about the P086 code after he replaced the shift solenoids

http://caddyinfo.ipbhost.com/index.php?showtopic=28472

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Looking at this further it is looking like a pressure solenoid, this code is in history.

P076 (E076) ......................................... Transmission Pressuse Solenoid<<<<<<<

P109 (E109) ....... Keep Alive Memory (KAM) Reset/PCM has lost primary battery power (not a big deal battery must have been disconnected)

A012 ........................................... Low Side Temperature Sensor Circuit (related to your AC)

A tranny shop or a dealer may be able to test the pressure solenoid or it may even be possible to energize it via the OBD1 overrides... Ill see what the manual states, I have one for a 94 that is also OBD1

When a code is followed by current or history...........what does this mean? The battery was disconnected, this is how i can reset the system so the car is useable, sometimes it lasts for months and sometimes days, i think it's posessed :-) , but thanks for the help, i really appreciate it.
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There is a way to do it within he diagnostics, but I forget how to do that many someone familiar with OBD1 can comment. But you can go to the link in my signiture here and find out how to clear codes

The other way is to disconnect the negative terminal of the battery and reconnect, but that is not the recommended method

I sent MAC a PM to see what he learned.

The description of P086 is this

The gear ratio of the transaxle is calculated from the ratio of the turbine speed over the output speed. It has to do with whether there is proper commanded 'line pressure' and causes range from a stuck or inoperative pressure regulator valve, slipping or a pump that is leaky, depending upon whether the pressure is high or low.

I good tranny shop should be able to diagnose this, using a pressure gage and using the PS20 PCM override while monitoring pressure changes at PD71 (transaxle pressure switch) and PD76 (transaxle gear ratio).

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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There is a way to do it within he diagnostics, but I forget how to do that many someone familiar with OBD1 can comment. But you can go to the link in my signiture here and find out how to clear codes

The other way is to disconnect the negative terminal of the battery and reconnect, but that is not the recommended method

I sent MAC a PM to see what he learned.

The description of P086 is this

The gear ratio of the transaxle is calculated from the ratio of the turbine speed over the output speed. It has to do with whether there is proper commanded 'line pressure' and causes range from a stuck or inoperative pressure regulator valve, slipping or a pump that is leaky, depending upon whether the pressure is high or low.

I good tranny shop should be able to diagnose this, using a pressure gage and using the PS20 PCM override while monitoring pressure changes at PD71 (transaxle pressure switch) and PD76 (transaxle gear ratio).

I looked at Rock Auto for the part, there seems to be more than one. If you have time to look there which part do you think would be the correct one to buy. they are cheap enough to just go ahead and change it and try.

Thanks

Scott

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Are you talking about changing the pressure solenoid? While the part is cheap, changing it is a BIG job. You need to confirm that the pressure solenoid IS in fact the problem and that you have NOT done damage from slipping that you reported

Here is my thread where I replaced the Input Speed Sensor, TCC solenoid, Pressure solenoid, this is a rough job

http://caddyinfo.ipbhost.com/index.php?showtopic=13481&hl=p0717&st=0

I can't help with which one is correct, keep in mind that you need a whole host of parts when you do this job. Take a look at my thread and see what you think

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Are you talking about changing the pressure solenoid? While the part is cheap, changing it is a BIG job. You need to confirm that the pressure solenoid IS in fact the problem and that you have NOT done damage from slipping that you reported

Here is my thread where I replaced the Input Speed Sensor, TCC solenoid, Pressure solenoid, this is a rough job

http://caddyinfo.ipb...1&hl=p0717&st=0

I can't help with which one is correct, keep in mind that you need a whole host of parts when you do this job. Take a look at my thread and see what you think

Looks like i am going to take a shot at changing the pressure solenoid, got one from rock auto (AC Delco) I've got nothing to lose. I looked at all the threads you sent me but none had info on changing the solenoid. Have a friend familiar with trannies and he's giving me a hand on Friday, hopefully it doesn't turn into a BLACK Friday :-) for the caddy!

Scott

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My thread that I linked you to showed you how to get into the side pan by tilting the carriage, you will need the location of the solenoid to find it. As I noted my thread was involving the ISS sensor, TCC solenoid and Pressure solenoid which I replaced all at once. I believe you will need other parts besides the solenoid to do this job.

Good Luck

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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My thread that I linked you to showed you how to get into the side pan by tilting the carriage, you will need the location of the solenoid to find it. As I noted my thread was involving the ISS sensor, TCC solenoid and Pressure solenoid which I replaced all at once. I believe you will need other parts besides the solenoid to do this job.

Good Luck

So if I'm understanding this correctly, the pressure solenoid is behind the side cover of the tranny. I can't find any real detailed instruction for changing it...thanks and Happy Thanksgiving All!!
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Yes its behind the side cover, you will NOT find any detailed instructions to get to the pressure solenoid, but see this for good reading and background its for the IS sensor but its good reading if you like instructions

http://www.caddyinfo.com/pc0717.htm

Here is a component resistance chart that will be helpful

http://www.caddyinfo.com/4t80e_componentresistencechart.htm

I have an ATRA rebuilding manual, Ill post a location if I get a chance

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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