Finally a sunny day to drive the Caddy into work!

Alas when I set off down the road, I realized she wasn't shifting from first to any higher range.  I just drove it on Saturday and it was shifting fine.

I checked the fluid level and it was spot on, looked clean and smelled fine.

After work I put it on the hoist and first started with the vacuum modulator.  At idle I'm getting about 15 psi of vacuum from the engine to the modulator, under acceleration about 18psi.  I put the vacuum pump on the modulator and pumped it up to 20 psi and holds for a bit then slowly drops off but not a drastic fall.  No fluid dripping out out of the modulator either.

Replaced the hose between the vacuum pipe and modulator and tested the car on the hoist.  Still no upshift from first.

Next I removed the governor and the weights move freely.

I dropped the pan and found no abnormal debris in the pan and fluid was clean and not burnt.  Filter was installed tightly.

Other than running a bit rich and loading up at idle, the car has been running and driving great.

Any thoughts?

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What model and year is your Cadillac ?

Do you know if you have a Hydromatic or the Turbo 400 trans in your car ?

Did you check the trans fluid —at an idle at operating temp?

Our trans do not shift if the trans fluid is not topped off  so check that ( down a quart or more ) 

If a 64 turbo trans check the vacuum line from the trans to the back of the carb for leaking or damage to the hosing there 

If a 63 check the TV rod on the side of the carb looking for any irregularity there as that rod controls the trans shifting  

Just some basics but a trans repair may be needed after the basics are checked 


Oops, sorry 1964 Deville with Turbo Hydramatic.

The vacuum line is steel and the rubber connector was good although I replaced it just to be safe.

Fluid was checked at idle and operating temp.

Oh, it was such a stressful day that I forgot to mention that I had made it about a half mile down the road when I realized there was a problem.  I turned back and it seemed like it was quickly losing forward momentum but not noticeably slipping.  Engine wasn't wound out but it was like we were dragging an anchor.  

Failing torque converter perhaps?  I did notice a slight vibration a few weeks ago but I thought it might be a driveline issue but it didn't happen again so I forgot about it.

It's good news that you don't have slippage, and that your fluid is clean.  You've checked the governor and the modulator, and those are two of the first three things that will cause no-upshift conditions.   The third easy one is your downshift solenoid and downshift switch.  If the solenoid is open or the switch shorted, the detent circuit engage and delay upshifts.  Have you checked this?  
Quickly losing forward momentum means engine braking is on, which means one of the bands is applied.  This is normal for both first and second gears. If you're not getting upshifts,  this means at least the pump pressure is reaching the servos and holding the bands.  Along with no slipping, this means that  the main line circuit is probably AOK, and you have a line misdirect (such as solenoid stuck open or other valve body issue, bad filter on cars with paper elements).  
The symptoms of a bad torque converter are (usually) slippage because of vane failure or stalling at idle  because of lockup.  The converter won't slow shifts by itself without causing slippage because it works independently of shift valve and mainline pressures.  


Looks like your tip about the downshift switch got this gentleman smiling again 



Looks like he got it figured out himself.  Sometimes you just gotta step away and clear your head to see what's right in front of you, I think this is what happened here.  


I do second your thoughts on walking away  and sorting a given issue out 

I often find myself devising an approach to a given problem just before I wake in the morning 

That may be where the thought about— sleeping on it - comes from 


Thanks Mark!  I'm feeling really good tonight now that I don't have to rebuild a transmission :D

Could be time for a trans shop to trouble shoot the problem as you covered the basics and they  are good 

The turbo hydromatic is a very bullet proof trans with very few issues over the many years I am on the site since 2006 
I do not recall a Turbo hydromatic trans needing to be rebuilt on this site in all that time myself 

A few of the boys on this site have more knowledge about trans issues than myself and should be along in a while for advice 

I would check the gear shift linkage at the end of the steering column ( under the hood )and the linkage on the trans to be sure the car is getting into the Drive gear and not into a lower gear 

Looking for a linkage that may have unattached it self or gotten loose somehow there 

I do know of two cases where the trans linkage on the trans itself got loose and prevented the car from going into gear correctly 


Well today was my lucky day.  I came home with a clearer head and found that the transmission kick down switch was stuck in the energized position.  A little penetrating oil freed it up and the car shifts beautifully again.  Whew!


Glad it was an easy fix  for you 

First I have heard of that switch causing  such trans problems but does reinforce what a great trans the Turbo 400 trans is for the long haul regarding reliability 

I kept thinking this has to be something simple knowing how good this trans is 




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