Questioni have 3 major problems that i need fixed and i dont know where to start. first i need to know how to check for a vacuum leak in the lines. i was told by autozone that its not getting the pressure needed. also i need to know where the speed sensor is located and how to change it or make sure there isnt a short somewhere. and lastly they said i need a transmission control module, where is that located and how would i go about changing it? also is there any way to tell if there is in fact something wrong with these items so im not changing them when i dont need to. thank you so much. please get back to me as soon as possible. i appreciate it.
AnswerHi, Stevi. I have some concern about what you're attempting to do, as it seems likely at least some of your questions may be based on improper information. If your question is the result of advice given to you based on AutoZone telling you where to look for the problem, I think it'll be much more efficient and productive if you can tell me the actual trouble codes they read from your vehicle. These trouble codes will typically be five digits of the form Pxxxx were the x's represent digits.
Regardless, here's the information I can give you in reference to your questions.
There are several ways to check for vacuum leaks, but as I presume you do not have access to a scan tool which will read engine data, your best bet is probably a visual and audible inspection. To start, simply check each of the vacuum hoses coming off the engine for any leaks. One hose should go to the brake booster, one should go to the purge control valve, and a third should go to the PCV valve. If you find no issues, you'll need a section of small inside diameter hose (such as 3/16"). With one end of the hose at your ear, move the other end of the hose around the areas where the halves of the intake come together and the areas you can access where the intake manifold adjoins the cylinder head. If there is a vacuum leak, you should be able to hear the air flowing through the hose.
Your vehicle has up to seven speed sensors. I'll need to know which sensor you're attempting to diagnose in order to give you pertinent information. Again, if this is the result of a diagnostic trouble code (DTC), simply following up with the code will in most circumstances allow me to know which sensor needs to be checked.
The transmission control module (TCM) is located underneath the heater box. To access, remove the front side panels from the console. I'll stress, though, that TCM problems are *very* rare and the TCM is quite expensive. You should not replace this component unless you are quite sure that is your problem. Typically, there's little way to test the TCM itself, so diagnostics usually involve a process of elimination whereby other potential causes (which can be tested) are eliminated.
