1995 Cadillac Deville Transmission downshift problem?

ANDROID_04

MEMBER
1995 CADILLAC DEVILLE
V8
FWD
AUTOMATIC
17,477 MILES

A month ago I noticed that my car started shaking a little for a few seconds at random times, when I would brake kind of hard. I thought it was a problem with the brakes, had those checked, and they were fine.

The shaking happens more often now, and I can make the car shake for a few seconds when I brake kind of hard. The shaking seems to come from the engine compartment, and sounds kind of "grabby" where something quickly alternates between letting the car move and stopping the car (which made me think it was the brakes at first).

A few incidents that worry me:
1. A few weeks ago while driving at 35 mph I slowed down to let the car in front of me turn, and afterwards when I pressed the gas to speed up the engine sped up without the car speeding up. So I let go of the gas, press it again, and the car speeds up.
2. Today I slowed down to make a turn and the car shook like described above, when I pressed the gas the car didnt speed up. So I let go of the gas, press it again, and the car speeds up.

Sorry for the long post, but I cleared by computer codes and reread them:
IO39 Current
IO52 History
TO83 Current

5 Replies

BUZZSAW

MECHANIC
1,198 POSTS

The IO 39 and TO83 are your trans codes, torque converter clutch prob, its not the converter persay its the pump shaft seal, that goes into your converter is where the problem lies.

Also if you brake hard and get a vibration it is your brake rotors are warped, try this with the brakes go about 40mph and hit the emergency brake( with it in drive it wont stick ) if it vibrates its in the rear brake rotors, even know pads are good rotors can be warped

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Monday, April 21st, 2008 AT 1:11 AM

ANDROID_04

MEMBER
5 POSTS

I thought the IO39 is the reason I see Service Ride Control message, and my car has a hard ride. And I thought TO83 is the reason that I see the Brake Fluid Low message (bad sensor).

My brakes rotors are not warped, like I said at the start of these symptoms, the occurrence of the "shaking" was random and not repeatable at first.

Now it is more regular, but still does not occur every time. I am thinking it is a downshift problem because this happens when slowing down quickly and because of the 2 incidents mentioned where my car's engine was not connecting with the wheels.

I see a solenoid on the transmission that has a vacuum hose connected to it, and the rubber ends of the hose look cracked. Can this solenoid be the cause of trouble?

Thanks for helping me.

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Monday, April 21st, 2008 AT 10:57 AM

BUZZSAW

MECHANIC
1,198 POSTS

I thought the IO39 is the reason I see Service Ride Control message, and my car has a hard ride. And I thought TO83 is the reason that I see the Brake Fluid Low message (bad sensor).

My brakes rotors are not warped, like I said at the start of these symptoms, the occurrence of the "shaking" was random and not repeatable at first.

Now it is more regular, but still does not occur every time. I am thinking it is a downshift problem because this happens when slowing down quickly and because of the 2 incidents mentioned where my car's engine was not connecting with the wheels.

I see a solenoid on the transmission that has a vacuum hose connected to it, and the rubber ends of the hose look cracked. Can this solenoid be the cause of trouble?

Thanks for helping me.[/Quote:cbc516ac25]

yeah your right on the codes, was thinking about a 93 deville, looked in my 97 book you got it right, thats what I get for not looking it up, sorry

there is no vaccum to the trans anymore, your trans shifting is done by the computer and soleinoids and other sensors on the engine

on a caddy it will throw codes for trans probs, if they are electrical and some for fluid pressure probs

IO39 is a electrial part of the struts, really there is nothing wrong with them unless there leaking, the replacements are non-electrical and a relay or a cut wire is the fix on the RSS module to get the code to go away

maybe you need to fix that low brake fluid sensor it could be your prob, if it is low it messes with the traction control maybe thats what your feeling the ABS activating

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Monday, April 21st, 2008 AT 4:32 PM

ANDROID_04

MEMBER
5 POSTS

As far as the error codes affecting the transmission, I am pretty sure that is not the case because I have had those same error codes for the past year. The brake message came on after the brake master cylinder went bad and was replaced 1 year ago. The mechanics didnt do anything about the sensor.

I had my transmission flushed and filter replaced at the dealer like 3 or 4 weeks ago, and the problem still occurrs.

I replaced the cracked hose, still the same. I replaced a blown Air Ride Control fuse, still the same.

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Monday, April 21st, 2008 AT 4:57 PM

CPURK1