All out of ideas. Trans problems...Help Please!!
 

Hello everyone, so here’s my problem...08 h3 hummer 3.7 185,000 miles. Starts fine, reverse makes somewhat of a bang but still works fine, move to drive hit gas and once I hit exactly 20mph revs go high, loud noise (high revs), no speed gain at all. Can only drive 20 mph or lower. Trouble code was p1818 but now no code is being thrown. Trans oil has been checked, fluid was dark not original red. Transmission oil change was done roughly 10 months ago, driven less then 25k since then for sure, idles fine, only issue is the high revs when barley passing 20mph and no speed gain past that, works at or below 20mph. Recently doing this all diy method since I’m on a budget. I understand the expenses that could be at hand & are fully aware of a possible rebuild but if anyone can PLEASE help me in figuring out what could be the culprit I would appreciate it enormously. Thank you everyone!

https://www.google.com/search?q=gm+c...hrome&ie=UTF-8

Look at the above link and research your code. Your Transmission has a problem...

Time for a rebuild. You got 185,000 miles out of it. That's pretty darn good.

185K miles is better than pretty darn good. Time for a rebuild.

Stuck in limp mode, check/clean connector and check wiring to the trans.

Thank you everyone for getting back with me. This forum has been a great help to me for the time I’ve had my hummer & I really appreciate what you all do. I’ll update once it’s fixed should be by Saturday. Thanks again!