Transmission problems, anybody experience this?

Concours · #1 (**permalink**) 03-26-03, 10:48 PM

This is starting to happen on occasion, when I decelerate, then go to speed up again, under light throttle, it acts as if the trans is slipping, sort of huckle bucks a little, also I noticed the speedometer will register 0 while I'm doing 40 or 50. Then it will jump around and catch the speed. Also the service engine light is coming on. I have not had a chance to pull the code yet, scared to! I'm sure this won't be a cheap fix.....
I have a 94 deville concours with 76K on it. Anybody else experience anything like this?

Chuck C · #2 (**permalink**) 03-27-03, 01:18 AM

here are my experiences (two of them) maybe they could help

1) back around 50,000mi my car would suddenly burst with acceleration and then stall. i.e. I would be driving under normal city conditions, give it a light touch of gas, release, and it would go bonkers! both tach and speedo would shut off and on again. Real scary to drive especially when I had to use the emergency brake to stop b/c all the power went out when it stalled! bad EGR value (~$500 I think)

2) at 70,000mi I had a similar problem. Idle was real high and wouldn't calm down. Then the engine would stick at around 3k rpm when in park but drive normally when in drive. new system computer (~$400 for the part)

both times: Service Engine Light

hope that helps

elwesso · #3 (**permalink**) 03-27-03, 10:44 AM

It sounds like a bad speed sensor. They go out in the trannies, and unfortunately, the tranny has to be lowered to get to it. i am not for sure if the speed sensor causes the engine light to illuminate. ~1200 to replace that. But it could also be something messed up in the computer. You may see if you could get it flashed.

kcnewell · #4 (**permalink**) 03-27-03, 10:50 AM

Check your codes! If it's a sensor it'll show up! You have on board diagnostics on that car! Probably not that big a deal! Let us know what you find out...

Concours · #5 (**permalink**) 03-29-03, 07:15 PM

Vehicle Speed Sensor.

$21. at the dealership.

Remove left front tire, about half arms length thru wheel well on top of the transmission bell housing. Took about 45 minutes to replace, Hardest thing was working the one bolt out that held it in and undoing/doing the connector with one hand. Could not get both arms in there to work on it.

Not anywhere near as $$$$ as I thought!

elwesso · #6 (**permalink**) 03-29-03, 08:14 PM

Hey thats great. I did some research about the speed sensor, and it must have been a different one than i was thinking of. On caddyinfo.com it says you have to lower the tranny to do it, costing about $1000!! But great that you got it fixed!

jadcock · #7 (**permalink**) 03-30-03, 10:15 PM

There are two speed sensors. One is the input shaft speed sensor, which senses the speed of the tranny input shaft. This is obviously deep in the transmission and is the expensive one to replace. The VSS, Vehicle Speed Sensor, is the one that drives the speedometer and provides vehicle speed to the PCM and is located on the right "tailshaft" of the transmission.

elwesso · #8 (**permalink**) 03-30-03, 10:26 PM

Interesting, is there any way to tell which one is bad???

I guess in this case he got lucky!

jadcock · #9 (**permalink**) 03-31-03, 09:12 AM

The code I reckon.

elwesso · #10 (**permalink**) 03-31-03, 05:32 PM

Thats what I thought, but I didnt know if the OBD would be specific enough to say which sensor is bad.

dts92 · #11 (**permalink**) 04-09-03, 08:31 PM

You might have a defective control module...aka computer when I first got my 92 DTS it had similiar symptoms...I made the seller fix. After all new shifting solenoids and new wiring harness for Transaxle...still did it....fuel pressure was fine so no problem there...they took a look at computer and badabing! Replaced it and the car runs like I drove it off the showroom! Here is one thing though...when I get in and start up there is a noise like a compressor coming from left front strut area...stays on for a few second then stops..no warning lights....any Ideas?

jreld · #12 (**permalink**) 04-13-03, 04:08 PM

I have a 96 Eldoradro with a similar problem. I get a hard shift at around 42mph, knocks the rpm from 1600 to 1100. Also, the speedometer drops to zero at around the same speed, but very intermittent. I haven't had the Check Engine light, though. Also, only once, the engine acted like it was in neutral when I went to accelerate, I too am afraid to have it checked!

Quote:

Originally posted by Concours
This is starting to happen on occasion, when I decelerate, then go to speed up again, under light throttle, it acts as if the trans is slipping, sort of huckle bucks a little, also I noticed the speedometer will register 0 while I'm doing 40 or 50. Then it will jump around and catch the speed. Also the service engine light is coming on. I have not had a chance to pull the code yet, scared to! I'm sure this won't be a cheap fix.....
I have a 94 deville concours with 76K on it. Anybody else experience anything like this?

elwesso · #13 (**permalink**) 04-13-03, 09:48 PM

Again most likely a speed sensor. The only thing is there are 2, one mounted just behind the wheel well (easy to get to) and another one on the tranny (very hard to get to). The sensors themselves are about 120, but labor can be up to 1000 to lower the tranny to get to that sensor. Make sure you pull the code.

eehoepp · #14 (**permalink**) 04-19-03, 10:08 PM

If the spedometer drops to zero, I would first suspect the vehicle speed sensor, which is the one on the trans tailshaft (and, fortunately, the easier one to get to).

Katshot · #15 (**permalink**) 04-20-03, 12:40 PM

Quote:

Originally posted by eehoepp
If the spedometer drops to zero, I would first suspect the vehicle speed sensor, which is the one on the trans tailshaft (and, fortunately, the easier one to get to).

I would agree with Eric. And yes there are seperate codes that would help point to one sensor over the other.