Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 2 of 2 Posts

·
Registered
2008 chevy trailblazer_lt
Joined
·
30 Posts
Discussion Starter #1
Is that normal for TB's? Every other vehicle I've driven (including pickups with the 4l60e) have locked up the converter while cruising down a 45 mph road, but my TB doesn't seem to ever lock the converter unless I'm going at least 60 mph. I've even bumped it down to 3rd on a 55 mph road and it still leaves the converter unlocked. It drives fine, doesn't have any codes, gets 'normal' gas mileage, fluids are all the correct color, etc..... It just doesn't seem right to leave it unlocked so much and could be leaving some MPG's on the table.
 

·
Registered
2003 gmc envoy_sle_xl
Joined
·
9 Posts
No, it's not normal. It won't lock up until the trans oil reaches a minimum temperature of ~140 deg F. Then it will lock up, once you are going at least 40 and in top gear (OD).

You might check that you are getting a good temp sensor reading. OR you may have a external trans cooler that is actually cooling too much to let it lock up. Finally, you may have a bad lock up circuit.

I've found that even a little extra throttle will keep it from locking up. Once I'm at speed and in OD, I back off the throttle just a bit and after a second I'll see it engage and RPMs drop. After that, only small throttle inputs will keep it locked up.
 
1 - 2 of 2 Posts
Top