Lock-up torque converter problem?

When driving between 35-55 mph up a gradual slope in my 92 Mercury Sable wagon (it has 125K miles on it) I often feel a quick shudder in the chassis. I do not see any movement in the tachometer or speedometer. There is no noise. The shudder may happen just once or several times. I think the lock-up torque converter is slipping in and out of the lock-ed up position. I do not use the car much and know I can have the converer unplugged, but is there any danger in continuing to drive it this way? It seems to occur more frequently since it first appeared about 10K miles/two yeas ago.

Skypilot ("Army jargon for a chaplain)

Yeah, sounds like you’re on the right track. There could be a risk if you continue to drive it this way, if the converter locks up and decides not to UNlock. I’d get it looked at soon.

I know many people just don’t like having a piece of equipment that is not operating correctly but I ask would you really put any serious money (over 100.00) into this car? It is at a point that if it requires any work at all dispose of it JMHO.The possibility of getting stuck somewhere in this car brings out a new set of decision making variables.

Reading the stored computer trouble codes will tell you if the overdrive is failing.

Find the test block (engine side of firewall on passenger side).
Use a jumper to connect Brown wire to the Gray/Red wire on test block.
Turn the ignition key to start (don’t crank).
Read the 3 digit codes from the flashing yellow CEL on dash.
Digits are flashed twice in groups of three.
See more info at

There are lots of sites on the net that cover this procedure.

I agree with oldschool. Any repair for this will probably exceed the value of the car. I would probably leave it alone. Unplugging the converter clutch will cause the transmission to run too hot and just damage it further.


Sadly, Padre, I have to agree with those who said that this is not worth fixing on a 17 year old vehicle.

I would suggest that you drive it until it dies, being sure to carry a cell phone with you at all times. When it dies, it will be time to look for new transportation. In fact, it might be prudent to begin your search for new wheels before this car goes to auto heaven.

The TCC might not be unlocking when it should (going to slow) and there might be a simple fix for it, I don’t really know. I might add that I had a '93 Caravan that had a mechanical downshift connection that was shuddering at around 35 mph and the downshift connecton had to be lengthened a little.

Thanks to all of you! Here is some more information including some from Tom M.

In one of the Dear Tom and Ray replies for June 2009 about a 2000 Saturn, Tom says the following:

?TOM: Since the scan showed a code for the lock-up torque converter, and the symptoms fit, too, I’m going to go way out on a limb here and suggest that your mechanic check it out. It’s easy to do. He can simply unplug it for you.?

So Tom apparently thinks the converter can be unplugged. In a reply to another letter, one of them says the decrease in gas mileage is not much.

The Sable is our second car. We now drive it only when we need two cars and usually only around town. My guess is that we will put less than 800 miles a year on it. It is a good second car. But I won?t if it is unsafe to drive. If Tom is right that the converter can be unplugged, we will have that done.

So the question is, Is Tom right that the converter can be unplugged?


You can unplug it to check and see whether it IS the converter clutch causing the shuddering but no, you should not leave it unplugged as a cure to the shuddering. Like I said before, unplugging will cause the transmission to run hot and WILL damage it further.


Transman; I usually agree with your assesments and you have helped me a few times, BUT I do not believe that unpluging the converer clutch would cause any heating or damage. Heck the thing runs unlocked most of the time in traffic anyway.

By “converter clutch” I assume you are talking about the “lock-up torque converter solenoid” … if that’s the problem simply run the transmission in the second Drive (small D) position and see if the shuddering stops.

Believe me, driving with the converter clutch unplugged WILL cause the transmission to run hotter. Heat is the #1 enemy of an automatic transmission. If you dont believe me, ask any certified transmission tech.

Heres one example:
Read the frequently asked questions #4 and #5



Thats not an indicator either. You still have lockup if you take it out of O/D, it will just lockup in 3rd gear instead.


Well, friend, can you explain WHY the trans will run hotter if TCC is unplugged??

Well, friend, torque converters generate heat, a substantial amount of heat from slippage. The lockup clutch physically connects the pump to the converter reducing the slippage thus reducing the heat. Put simply, like I said twice before, DONT DRIVE WITH THE CONVERTER CLUTCH UNPLUGGED.


Transman, you have convinced me that the converter cannot be left unplugged. You said that you “would probably leave it alone.” I take that to mean that I can safely continue to drive it as long as I have a cell phone to call for help when it won’t go any further. Is that right? My wife does not drive it anymore except maybe less than a mile to go to the store or the PO, etc. In the meantime, I plan to sell it as it has other problems like a non-functioning AC, some rust, and aging tires, but it may take me awhile to sell it.

For a couple of bucks you can add some trans medic, trans-x, etc., and possibly get miraculous results. Try it and let me know. In fact, I’ll pay for the stuff if it doesn’t work.

You can add a product from LubeGard called Shutter Stop to the tranny fluid. This is formulated to eliminate TCC shutter.


For the amount of driving your wife does, it will be safe. I dont see minor converter clutch chatter as something that will leave you stranded on the road, also what Tester mentioned with the Lube Gard is good. Lube Gard products are very good and trusted by most trans techs.


The way I read the original OP There was a vibration like when you need to shift to a lower gear. This could mean the TCC is still locked up when it should be released. I had that problem once and adjusted the downshift lever. Now this car may not have any way to adjust the release point. There might be something that would change it.