OK, so long story short. Last year I was driving on a back road in my community and road work was going on but there were no signs to indicate this. There was a huge hole all the way across the road and i hit it at about 45mph. Since then once the car first starts up and drives it shifts fine, but after 5 minutes or so it will start to shift hard and jerk the whole car. The only reason i did not get this fixed at the time is because i was extremely poor. But anyway I had a guy at Advanced Auto pull codes for me. He wouldnt give me the actual codes but I know that its the Transmission Control Module, Speed Sensor, Solenoid, and Camshaft Position Sensor.

I know that the Camshaft Position Sensor probably doesn't effect it because it was out WAY before the incident. My problem is that i don't know which solenoid it is or if its the Input or Output for the speed sensor. Also, I have contacted Transmission Shops/ Tire Shops within a 50 mile radius of where i live and NOONE will look at it for me, they all just give me a number to another shop and tell me they will do it. I am not a Mechanic by any means but I have decided to do it myself. So i guess my questions are:

How do I figure out which Solenoid is out?
Should I go ahead and buy the Output Speed Sensor or Input?(Don't have money for both right now)
Where are all of these things located on the car?

I drive an 09 Cobalt LT Coupe 2.2 Auto
I can't wait anymore, I just had a baby and need to get this fixed ASAP

Thanks in Advance,
Matt

 

what year is your car? Sorry if I missed it?

 

Sorry missed the bottom part with car year and was driving. So there are a couple solenoids that run different gears which makes sense when you say its fine when first cranking, which is just you shifting to get the right gear where the issue is or starts.


The most common failure related to electrical components is the failure of the solenoids. The transmission will have one solenoid for the 1-2 shift, one for the 3-4 shift and one for the lock up torque converter and a few more. I loaded a pic that was generic but should be the same for these cars and years roughly but should give your location for the ones you need..




13 - TFP Manual Valve Position Switch Assembly
46 - Input Speed Sensor
62 - Output Speed Sensor
305 - 1-2 and 2-3 Shift Solenoid Valves
305 - 1-2 and 2-3 Shift Solenoid Valves
312 - Pressure Control Solenoid
335 - TCC Control PWM Solenoid

 

first off, if the transmission is shifting into each gear, your shift solenoids are working and not the problem. the shift solenoids in gm transmission rarely fail, people will lead you to believe otherwise, but in my 10 years in the transmission industry i replaced maybe half a dozen. the pressure control solenoids can cause an issue, however it usually causes low line pressure and burns the transmission up.

the cause of your problem more than likely not even inside the transmission, the tcm (trans control module) is likely in a fail safe mode because of an input fault. to even begin diagnosing the issue you need the exact codes that are in it, then you need to diagnose those codes. really you need a scan tool or hp tuners so you can monitor the inputs and see whats going on. the tcm uses a number of sensors (maf, tps, map, coolant temp, output speed sensor, input speed sensor, engine rpm, just to name a few), if a signal is missing it could go into limp mode and have hard shifts. even an over oiled air filter (like a k&n) can foul the maf and cause hard shifts without there even being a code for it. the info provided (that codes are for speed sensor, solenoid, etc) really means nothing, you need code numbers to work from. for example, the speed sensor, input or output? and either sensor can have a code for open/short circuit and erratic signal, both completely different to diagnose.

my recommendation would be to find a transmission shop and book it in. tell them only that you went over a bump and it started shifting hard, dont tell them you had the parts store read codes, all the service writer thinks is "this guy is gonna waste my time" and you will get blown off. the alternative is get someone to get the actual codes and go from there.