QuestionOne morning on my way to work I was driving my chrysler new yorker 1994.I was accelerating at the speed to 55-60mph (@ 3000rpm) all of the sudden I heard a squeaking sound under the hood after that my speed drop down to 40mph (@ 4000rpm). I turned back home and had to slow down just to keep the RPM low at the speed of 30mph (2500rpm).Next day I replaced and install a new transmission filter and transmission fluid. Yet I still have the same problem. I did not noticed any metal parts or chip that might have worned out from the transmission gears.What could have gone wrong? Where can I locate the transmission speed sensor from my car? thanks!
AnswerHi Fritz,
This is a common symptom of electronic controller transmissions. Have you ever been told about a "readout of the transmission computer" which is an electronic test for the presence of coded numbers representing different faults that the transmission is experiencing at the time when it locks up into 2nd gear? That exact lock up is what happens when the transmission computer notices something is wrong and so it protects the transmission by only driving in 2nd gear until it can be serviced so as to protect against any further damage. It is called "limp-in mode".
The fact that you found no debris is good. But it may also be the case that the problem is with electrical connections/computer or with the transmission fluid system (hydraulic) and those can be repaired without removing or rebuilding the transmission at much less cost.
The transmission has an electronic controller that has the ability to recognize malfunctions and store them in its memory as two-digit fault codes. An electronic readout device is plugged into a port under the dash to access the memory and tell you the fault code numbers. It would be worth spending about $50 to have this done just in case the problem had to do with the hydraulic or electronic parts. So a dealer or a competent independent transmission shop (but NOT a franchise type like Aamco where the usual answer will be to do a "rebuild") with a reader for Chrysler transmissions should be able to do that. Ask for the code number(s), what they mean, what repair is needed and how much it will cost. Be sure that they have the 6-pin ("bus diagnostic connector") reader plug adapter that will give them access to the memory via the port under the dash. This is NOT the same plug as is in the engine compartment (which is also a 6-pin plug but a different pin arrangement) for accessing the engine controller memory. Their reader also has to be equipped with a program (cartridge) that accesses the transmission computer. A Chrysler dealer will have this device called a DRB II.
Then write back and we'll evaluate what you were told, particularly what are the fault code numbers. I have the '94 factory repair manual and can look up what the numbers mean and what needs to be done to fix this.
You don't have to authorize a repair until you decide you understand the situation, and maybe get another repair estimate. You might even ask before they do the readout if in the case you decide to authorize the shop to do the repair "will the cost of the readout be credited against the cost of the repair"?
So take your time with this so you don't do any more unnecessary repairs. But that readout is the only way to avoid doing the wrong repair.
The output speed sensor is on the driver's side of the trans very near the end of the transmission, beyond the vertical shift lever and is about midline on the body of the trans. The input turbine sensor is at the same level but closer to the front of the trans. There is a fault code for that output sensor being faulty (57).
Roland
