Torque Converter doesn't seem to lock under 60mph? - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

Welcome Enthusiast! If you already own a Chevy TrailBlazer or GMC Envoy or perhaps thinking of purchasing such a vehicle, then you have come to the best TrailBlazer and Envoy site on the net! Rainier, Bravada, Ascender, and 9-7x owners welcome too!

You are currently viewing our site as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to search and post topics, communicate privately with other members, respond to polls, upload content, and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.
Join Today!
Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > Transmission Mods

Transmission Mods Performance Transmission Modifications is the premier GMC Envoy Forum on the internet. Registered Users do not see the above ads.
Thread Tools
Old 07-12-2019, 05:15 PM
kcducttaper kcducttaper is offline
Junior Member
2008 Chevy TrailBlazer LT
4.2L I6 4X4
Join Date: Sep 2018
Posts: 30
Torque Converter doesn't seem to lock under 60mph?

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.
Reply With Quote Quick reply to this message
Sponsored Links
Old 08-25-2019, 11:38 PM
jdmccright jdmccright is offline
New Member
2003 GMC Envoy SLE XL
Summit White 4.2L I6 4X4
Join Date: May 2009
Location: La Plata, MD
Posts: 8
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.
Reply With Quote Quick reply to this message
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum forums, you must first register.

Please enter your desired user name, your email address and other required details in the form below.
(Only letters, numbers, dashes and underscores are permitted for user names)
The user name that you choose is permanent and can never be changed.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

» Sponsors

Advertising Info

All times are GMT -4. The time now is 09:28 PM.

Chevy TrailBlazer and GMC Envoy Enthusiasts - Copyright 2004 - 2009 All Rights Reserved.
All trademarks referenced herein are property of their respective owners.
RSS Feed