Expert: Roland Finston - 6/9/2011

Question
QUESTION: I have a 96 chrysler concorde lxi and when car is warmed up when I speed up to about 40mph it shakes the whole car rather violently but it stops at about 50mph. After that if I try to speed up it shakes a little but not nearly as bad. It also sometimes shakes when idling at a stop but if I put it in neutral it stops shaking. The car has about 150000 miles on it and I got it with 136xxx miles on it. They had to replace the engine because it threw a rod. Do I need the tranny replaced to?

ANSWER: Hi Travis,
Try to get a fault code readout for free at a nationwide parts store, such as Autozone. These 4-digit numbers will likely tell us what is at fault and then we can figure out what to do. You could also try the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch both the odometer windowo to see if the mileage reading changes to show any 4-digit numbers and if no change, then do it again and watch the check engine light which will begin to flash, pause, flash etc. Count the number of flashes before each pause. Then repeat the key sequence and count the flashes again to be sure of an accurate set of counts. Then tell me the results and we'll go from there. Tell me which engine you have (L).
Roland

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QUESTION: I have a 3.5L and my check engine light isn't on but I went to autozone and they said something about a lockout torque converter

Answer
Hi Travis,
It would be a bit more helpful if they gave you a specific 4-digit number of the code. But based upon what you describe and the name they gave you, I suspect there is a problem related to the actuation of the torque converter's lock-up feature. How is the level of the fluid shown on the trans dipstick? If you have to add use only atf type +4.
If the fluid level is OK then there is a part called the LR/LU solenoid that may be causing the failure of the converter to positively lock up. The lockup normally is a good feature that saves on gas. That lockup mechanism could be serviced/investigated without removing the transmission by dropping the oil pan and removing the valve body for servicing. If that doesn't prove successful, then removal of the trans to service the torque converter itself will probably be necessary.  
I would suggest that you ask around to find an honest independent (not a franchise type) transmission shop that is familiar with the Chrysler transmission and see what they say based upon the code and the shaking. The torque converter lockup is called into play at about 40 mph so that is consistent with what you describe. Also if the torque converter doesn't unlock when you come to a stop then that too causes shaking or stalling. So the lock up device is likely the cause of your shaking.
Please let me know what you learn.
Roland
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