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1996 Cadillac Deville Transmission issues on 96 Deville

Tiny
JULIARAE
  • MEMBER
  • 1996 CADILLAC DEVILLE
  • V8
  • FWD
  • AUTOMATIC
  • 20,000 MILES
The car was being driven down the highway and suddenly lost acceleration. If you pushed the accelerator it was like revving it in neutral. All gears are now like neutral. Soon as that happened we got the 'Service Transmission' message. We ran the diagnostic check and have 3 codes:
P1139 - Heated Oxygen Sensor
P0301 - Cylinder 1 misfire
P1810 - TFP Valve Position Switch Circuit

What exactly does the last code mean (P1810)? Does this mean it is an electrical problem? A faulty valve? Any ideas or suggestions?

I appreciate any help or advise you can supply!

Thanks so much ~

Julie
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Tuesday, June 16th, 2009 AT 9:08 PM

7 Replies

Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
That TFP switch is just to validate which gear slector position the vehicle is in, it won't necessarily cause a 'slips in all ranges' concern. Have you checked the transmission fluid level and condition? Ideally it should be red, with no odor. As the fluid wears it takes on a brown color. If the fluid is full, and has a burnt odor to it, you probably have suffered an internal failure. With the amount of miles, it would not be unrealistic. Do you have reverse?
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Tuesday, June 16th, 2009 AT 11:23 PM
Tiny
JULIARAE
  • MEMBER
  • 4 POSTS
No, we do not have reverse - no gears, including reverse. However, the fluid does not smell burnt at all. It was low though. Added a quart, but still no gears. The level is still low however.
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Wednesday, June 17th, 2009 AT 12:20 PM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
It still sounds like you have an internal failure. About the only thing that would cause you symptoms and not be internal to the trans, is the center broken out of the flexplate. That would cause no pump/hydraulic pressure. Then again, with that the engine would not start either. It is hard to guess what failed internally, if you have no burnt smelling fluid, something hard may have failed. Pump drive shaft broke, pump itself, stator support, torque converter. The next step, and the first step in diagnosis, would be a transmission fluid line pressure test to see if there is pump output. If it lost pressure, that could explain the P1810. The range switch would have indicated a gear, and the tfp would not validate it, as it works on pressure.
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Wednesday, June 17th, 2009 AT 11:24 PM
Tiny
JULIARAE
  • MEMBER
  • 4 POSTS
I wasn't with them (my family) when it occurred. They did say they heard something, some kind of noise or sound, right prior to the failure - as if maybe something broke. Because I guess they asked 'What was that?' And then they knew! (Kind of) As they suddenly had no transmission operation.

So, I guess we need to next do the transmission fluid line pressure test to see if there is pump output. After that what do we do next - whichever way the result goes? No pressure means we replace the pump, or not necessarily? If there is pressure, one of the other parts you mentioned may need replaced?

I really appreciate your help! We have a great mechanic that does moonlight work for us. He ran the codes for me. He can help us, if he knows what to do. He is very good and has done a lot of work in the past for us. But he has never worked on a cadillac transmission and just wants to know what he is up against before he commits to anything. Not too long ago he replaced the heater core.
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Wednesday, June 17th, 2009 AT 11:41 PM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
In either aspect of the pressure test, I stilll believe it needs torn down. The transmission itself is pretty straight forward, if a person has automatic trans experience. The problem is getting it out. It almost definately requires a hoist, and other equipment. The engine needs supported, frame needs to come out, and transmission is then lowered from the vehicle. The parts I had mentioned are just some educated guesses, not necessarily the only things that could cause this. The price is also going to be a variable, until it is torn down and assessed to develop an estimate. There is the rebuilt option that may also be considered, and then just the R&R. You will get a warranty(or should), and the price difference may turn out to be comparable.
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Wednesday, June 17th, 2009 AT 11:57 PM
Tiny
JULIARAE
  • MEMBER
  • 4 POSTS
Okay, I will take this info to our mechanic and see what can be determined. It may be a little while, as he is pretty busy. Once I find out, I will try to let you know what the problem was. Thanks again so much for the information and advise! Julie
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Thursday, June 18th, 2009 AT 7:06 AM
Tiny
FRIENDLY22
  • MEMBER
  • 1 POST
Have 1996 Cadillac deville transmission problem it like it don't want to pick up speed it changing gear like it suppose to what wrong
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Thursday, August 18th, 2016 AT 5:35 PM

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