2006 Cadillac CTS Transmission Issue

It’s quite possible it could be a lazy solenoid, though, when they fail, they go down hard and stay there. With that said, though, you might still be in luck. You see most transmissions are controlled by the transmission control module (a fancy way of saying a specialized computer). The control module looks at many inputs including a number of sensors such as the mass airflow sensor, the mass air pressure sensor, the throttle positioning sensor and even a thermostatic sensor that ensures the transmission is operating within performance specs.

It is quite possible that one of those sensors could be failing and that could be causing your problem. It’s easy to check out as all you have to do is ask the technician to run a diagnostic scan with an OBD-II scanner and if there is a problem code stashed away, it will show up. It will tell you the part or area of the transmission that is failing.

Now, here’s a suggestion that is always a good starting point. Take a look at the transmission fluid. One part of my mind keeps on being nagged by the jerking as it goes into fourth. It could be a slipping clutch/band combination or it may just be that your transmission is slightly low on fluid. When this happens, the transmission relies on increasing internal pressure to compensate for the lowered fluid.

It’s one of those things that works most of the time and sometimes slips. It sounds like your transmission could be low just enough fluid so that all of the parts of fourth gear are mostly covered and work correctly, but there are times, say when accelerating, when there’s just enough force holding up the transmission fluid flow to make it go clunk. And, while you are at it switch out the transmission filter as it might just be clogged enough to prevent adequate fluid flow at times.