Trans-axle fluid leak

if its the the gear selector is moving and not going into gear ----under hood drivers side under brake mastercylinder is the top of transmission the gear selector cable connection is there check that it hasnt come off,loose or damaged ----=if selector does go into a gear and trans not responding look under drivers side and thru wheel wells for fluid leak ---theirs no dipstick so to check fluid
There is a black cap located on top of the trans almost directly under the brake master cylinder. It's about 2 inches high, 3 inches around. That's where you add the fluid. The checking procedure is as follows: Start the engine and allow the engine to idle until the transmission fluid temperature has reached the value specified. 104 degrees F.
Depress the brake pedal and move the shift lever through the gear ranges, pausing a few seconds in each range. Return the shift lever to the PARK range.
vehicle must be level with the engine running and the shift lever in the PARK range.
Remove the transmission oil level control plug.
The plug in an 11mm bolt located between the r/s axle seal and the oil pan.
Check the fluid level. The fluid level should be even with the bottom of the threaded plug hole.
If you remove the plug and nothing comes out, add about half a quart at a time until the fluid starts to dribble out. Once it stops, the level is good.this is the procedure to check fluid if their is fluid and problem still persists the transmission module and or internal transmission damage possible which a mechanic {transmission}would need to diagnostic check the following link has multi videos for the cobalt transmission 05 Cobalt Transmission Fill Yahoo Video Search Results

Some of these newer trans have NO dipstick. In the mfg. opinion, if there is not a leak, its full...A trans flush will remove the fluid and replace with new..Never staed if you were exp. any problem...

according to wiki.answers.com
"Chevy Cobalt has a sealed Automatic Transmission... no dip stick. Probably best to take it in to get service by trans shop if you think it needs changing or re-filling."
Or
"There actually isn't one. It's a sealed system. There is a cap to fill the transmission directly ontop of the transmission. If you need to check the level, lift the car in the air and there is a 11mm plug on the bottom of the transmission, With the car running (WARNING: THE CAR MUST REMAIN RUNNING WHILE PLUG IS OUT!!!!) take the plug out, the fluid should trickle out of the hole. If no fluid comes out add fluid. AGAIN DONT SHUT THE CAR OFF WHILE IT IS RUNNING OR ELSE FLUID WILL POUR OUT!"

http://www.fixya.com/cars/r6735274-check_transmission_fluid

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

If the trans is an automatic the dipstick is usually marked quite clearly and can be found near the brake-fluid reservoir. If the trans is a manual then you need to get under the car to find it. But, either way, if the trans needs fluid then it is leaking, and if it is leaking you need to get the leak repaired. A trans that is low on fluid will fail, and usually people don't realize they are low on fluid until it is too late.

According to the owners manual unless you drive in hilly, or heavy stop and go traffic like a taxi, you should never have to add trans mission fluid unless you have a leak. The manual doesn't even give a fluid capacity for the auto transmission. So I guess when you have to have the auto trans. filter changed, you have to take the car to a transmission specialist. If in fact the filter even needs to be changed. The manual leaks you to believe that the transmission fluid and filter are lifetime products.

the dealer or a trans shop will have to fix the leak, there is no dipstick.

There is no Transmission dipstick. It is all sealed. To service you need to take it to a shop or do it yourself, but be prepared to get really dirty.

There is no dipstick in this vehicle. When servicing the transmission what you drain is what you put back in the plug on top of the transmission. If the trans. doesn't slip, then you don't add any more fluid. Worked on a few of these. Good luck

This is how you do it.

Ensure that the transaxle case temperature is 70° to 90° F (21° to 32° C). With the engine running, shift transmission through all gears. With engine idling in PARK, remove the check plug from the transmission. If transmission has been overfilled, allow fluid to drain out. If no fluid drains out, add fluid through the TRANS FLUID fill cap under the hood on the driver side in 1 pint (0.5 liter) increments until it slightly flows from the check plug. Reinstall the check plug.