2004 trailblazer going in and out of gear

Electronically-controlled automatic transmission.. it could be as simple as control solenoid or a relay.

Sounds like your one of your shift solenoids is bad are you driving and it starts reving up at random?

Have the codes checked. Those lights come on for a reason. And those numbers will help us, help you spend less money.

sounds like a broken shift cable. (the connection between the shifter and the gearbox) common symptoms are the shifter move easier than normal.and does not move to any gears (not even park or neutral).

That weird noise is starter gear clashing with the flex plate gears, change the starter and hope it works.

Just a little low on freon can make it get too cold and it freezs if you in position to check the freon level you'll find with the system on high and the engine reved up the low pressure is below 25PSI. fill it to reved up is above 25 and your problem will go away. Low on freon will make it cold enough to frezze up and then warm up as the air does'nt go though the ice. it'll work good as you start up till it frezzes and after it's stopped up with ice it blows warm (it's really too cold). the more freon in the system the warmer it'll all blow because all the pressures are higher and it's the difference in pressures that make it cold.

1st things first, clean that throttle body with carb cleaner with the battery disconnected.


Check your motor mounts and transmission mounts for the vibration at start up and when your foot is on the brake. I just went through this with my TB. The mounts may look ok visually, but they may be going flat. Changing the gear oil won't solve anything you have described, however, it's time to change, then change it.

Did you recently change your spark plugs to a brand other than AC Delco 41-103's? I've seen platinum plugs make our TB's run rough also the worst is Bosch. Stick with the iridium Delco's, will have a smoother running vehicle. Hope something in here helps.

sounds like a defective OSS
seek assistance from your local parts store
they will pull codes for free

you may start finding a good mechanic and have your transmissions check, be ready for a transmission replacement. hope this helps

Sounds like you might have lost the tranny,or at least the shift solinoids inside the tranny.