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Transmission Slipping..(Was Shift Solenoids)


joeb

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Found many Sts vin 9 trans. U sure the final drive is not controlled by sprockets/chain under side cover? It's all done with differential? I read a bit about the 4t65 trans and I think they control ratio with sprockets? Yes the 4t65hd has a beefier diff and shorter pass axle but I assumed 4t80 ratio was controlled same way?

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I'm sure that the final drive ratio is set by the differential, which is driven by the transmission output shaft on the right side of the transmission. The differential splines into that, and both output shafts spline into output gears in the differential. It comes in three ratios, 3.11 for VIN "Y" Cadillacs, 3.71 for VIN "9" Cadillacs, and 3.48 for the 1995-1999 Oldsmobile Aurora with 4.0 liter 200 hp Northstar.

The PCM is programmed to look at transmission input shaft speed, transmission output shaft speed, and the VSS, and will throw a code such as P0730 or P1871 if the wrong final drive ratio is installed. That can't be reprogrammed, even with a Tech II, to my knowledge. But, the differential should be interchangeable between 4T80E transmissions, at least of the same year. There are changes year-to-year; for example, they changed the TCC from a viscous clutch to something more durable for the 2005 model year.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I am home now. Car is still at dads house. Can grab some pics soon. Am going to source used trans. Afraid it's time to part with car. I am really searching for newer fixer upper. Now that I have dropped subframe I feel comfortable tearing into next project. Another caddy. Gulp!

joeb- I am confused at the title of the thread. It says "Was shift solenoids" but you state you're searching for a used transmission.

Once you get the trans. fixed, the car should be fine.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I am home now. Car is still at dads house. Can grab some pics soon. Am going to source used trans. Afraid it's time to part with car. I am really searching for newer fixer upper. Now that I have dropped subframe I feel comfortable tearing into next project. Another caddy. Gulp!

joeb- I am confused at the title of the thread. It says "Was shift solenoids" but you state you're searching for a used transmission.

Once you get the trans. fixed, the car should be fine.

I changed the title at JOEB's request...

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Err, title is confusing now. I was wrong to title it shift solenoids. Turns out solenoids were fine. Trans will not shift. I believe due to antifreeze mixing with trans fluid and destroying the clutches ability to grip. Trans is trying to work but no friction on clutches/bands? When folks search for this thread in the future, I dont want them to go on a wild goose chase and think this is info for solenoid issues. Maybe in passing I suppose?

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i found another drain plug on front of trans. behind the abs module. you would never see it in normal maintenance. i know you can drain the side cover with the plug next to the screen in lower pan but i have never heard of this front plug being mentioned before. i wonder if it drains a bit more? i got another radiator. different rad, trans, conv so all of the old nasty fluid should be gone. i talked to another shop about the color of trans fluid. he leaned towards radiator fluid but said it was very rare.

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joeb,

Be sure to flush out the lines that go between the trans cooler in the radiator and the transmission to make sure all traces of the glycol are gone. You don't want any residual contaminated fluid in your replacement transmission.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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when trans and radiator are removed, there is not a whole lot holding up trans cooler lines. they are both on parts pile. i will flush them out with fresh fluid

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i found another drain plug on front of trans. behind the abs module. you would never see it in normal maintenance. i know you can drain the side cover with the plug next to the screen in lower pan but i have never heard of this front plug being mentioned before. i wonder if it drains a bit more? i got another radiator. different rad, trans, conv so all of the old nasty fluid should be gone. i talked to another shop about the color of trans fluid. he leaned towards radiator fluid but said it was very rare.

I've never heard of this problem with a Cadillac before. Perhaps there are others here with experience with a lot more Cadillacs that can say something.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I wouldn't want to use

i found another drain plug on front of trans. behind the abs module. you would never see it in normal maintenance. i know you can drain the side cover with the plug next to the screen in lower pan but i have never heard of this front plug being mentioned before. i wonder if it drains a bit more? i got another radiator. different rad, trans, conv so all of the old nasty fluid should be gone. i talked to another shop about the color of trans fluid. he leaned towards radiator fluid but said it was very rare.

If the plug actually goes into the side cover cavity, I wouldn't want to use that plug to drain fluid as it would make a real mess. I have not seen or heard of that plug.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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This is a supplementary drain bolt, I believe. I think it is referred to in the 1997 FSM on page 7-182 i the Fluid Filter Replacement section, at the end of the IMPORTANT paragraph that ends step two. You drop the pan, then remove the drain bolt to get the rest of the fluid out. They say to leave the torque converter alone - "You do not need to drain the torque converter during most service procedures."

There is a short section on "Engine Coolant in Transaxle" in the 1997 FSM on page 7-56. Below is this section in its entirety.

Engine Coolant in Transaxle

Notice: Antifreeze will deteriorate the Viton O-ring seals and the glue used to bond the clutch material to the pressure plate. Both conditions may cause transaxle damage.

Perform the following steps if the transmission oil cooler has developed a leak, allowing engine coolant to enter the transmission:

  1. Because coolant will attack the seal material causing leakage, disassemble the transmission and replace all rubber type seals.
  2. Because the facing material may become separated from the steel center portion, replace the composition-faced clutch plate assemblies.
  3. Replace allnylon parts including washers.
  4. Replace the torque converter.
  5. Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
  6. Flush the cooler lines after you have properly repaired or replaced the transmission cooler.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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It is fixed. The coolant temp sensor has a broken plastic latch from when I did my heads 5 yrs ago. I noticed the harness was unplugged and wanted to start motor and assumed it would run? Poorly. Erratic idle, cooling fans on and so on. Got new sensor and spent 2hrs trying to get it in. Than, motor ran fine, car shifts fine, no codes.

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Joe,

You installed a junkyard trans. right?

Glad to hear it is running well!

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Got it from a 99 eldo. 30k less miles than mine. Yard had pulled trans/motor and car was in yard. Had been sideswiped. Changed radiator too. Quite the job. Added almost 3 gal of trans fluid. I did it outside since temps were nice. It's in dads heated shop today. Was 30f last night.

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Glad to hear the good news

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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