Jump to content

Transmission


Recommended Posts

When I'm at a stop light and take off when the truck reaches 7th gear sometimes it will not accelerate so I would let off the gas pedal then give it gas then I would hear a thunk noise and it will take off does anyone know what the problem could be? It only happens towards the end of the day.

Link to comment
Share on other sites

the wire harness is a small one, and it runs over the left frame rail under the cab. I have replaced these due to them chaffing where it goes over the frame edge.   its costs under $150.00 3 years ago when I did the last one...   jojo

Link to comment
Share on other sites

On 9/16/2021 at 6:46 PM, kt_Engineer said:

What transmission do you have? If it is 12-speed MDrive, something seems to be confusing TECU where it is trying to go to low range (from high range) or could not go to Hi-Split in main box. Maybe splitter synchronizer is going bad.

I agree it sounds like the synchronizer this a weak point on the Auto a fairly common  Failure specially I its left with the second speed programing in reverse ! This is a theory  however ! But it Seems to knock the sycro cone loose from the hub due to its design it seems to happen more frequently on those with the two speed reverse program left enabled!

Link to comment
Share on other sites

19 hours ago, Andre Wright said:

Update got my truck back yesterday and its fixed the Mack dealer was right. So apparently a bad transmission wiring harness will cause your transmission to slip

Good to know thanx for posting your fix!

Link to comment
Share on other sites

  • 4 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...