Tranny bug

[jhall]

Hi Guys,

My in-laws purchased my '95 Deville some years ago. The car has been great for my mother-in-law, but has recently developed a problem with "lock-up" in reverse.

Pulled codes and got some items in the "history" (no active). One code is the PRNDL switch is malfunctioning (saw it happen while I was checking the tranny problem and got the note from the DIC). Other history codes were loss of communication with the PCM and a code related to the torque converter lock-up mode (likely from the PRNDL switch problem - the cruise control kicks out when this occurs).

The problem:

1) Placing the car in reverse sometimes causes the tranny to "lock" (usually first thing in the morning). The engine revs, but the car won't move. It acts like you are pressing the gas while holding the brake. If you play with it a bit, it will eventually back up, but is a it jerky in motion.

2) While the car is in neutral or park, there is a noise from the driver's side of the tranny. Sounds almost like a ball bearing "roar" or fluid rushing in the tranny. The noise goes away when the tranny is placed in D, 1,2 or 3.

Any ideas on this? Sound like a control valve in the tranny or possibly the pump going bad?

Any thoughts apprecaited!

[Cadillac Jim]

I would suggest that you clear all the codes and run it for a couple of days and post all of the recent codes.

It soundsl like you have a network problem -- i.e., wiring between the console and the PCM may be bad. Post all of the recent codes and we can probably tell.

[BodybyFisher]

I am looking at my manual for the 4T60E and there is a condition category called LOCKED UP IN REVERSE OR DRIVE and it states to inspect FINAL DRIVE INTERNAL GEAR (693) for deformed or dented parking pawl (694).. The jerkyness could be the parking pawl engaging intermittantly.. The parking pawl is affected by the manual linkage adjustment if I recall, and that could also be the reason for your PRNDL switch issue.

The parking pawl if it is under tension can cause noise to be transmitted louder than normal, just a thought. For instance, if you are on a hill and you put the car in PARK engaging the parking pawl, and allow the weight of the car to rest on it, you will hear a whine transmitted, until you take it out of PARK..

There is another category called HARSH ENGAGEMENT OR ENGAGEMENT SHUTTER IN REVERSE inspect these components (doesn't sound like your problem):

2nd Clutch housing and Drum assembly (617)

Reverse Band Assembly (615)

#5 checkball

Servo Cushing Spring (45)

Mike

[Ed Hall]

2) While the car is in neutral or park, there is a noise from the driver's side of the tranny. Sounds almost like a ball bearing "roar" or fluid rushing in the tranny. The noise goes away when the tranny is placed in D, 1,2 or 3.

This is a classic symptom of the sprag ready to go out. If it was my car, I would not drive it since once it lets go, it'll cause much more damage.

[BodybyFisher]

Ed, I had a sprag let go in my 91 Seville. My symptom was a loud metalic (scary) knocking in neutral or park while increasing the RPM to about 1200 to 1400...it did not happen while the car was in gear. At times the car would surge forward slightly when the noise occurred... My tranny required a total rebuild when it blew, I had the noise for about 50,000 miles.

The guru and I had long conversions about it at the time and he diagnosed it correctly as the sprag.