4L80E Shift problem - Diesel Truck Forum - TheDieselGarage.com
Thread Details Posted by rspasoje, this thread has received 2 replies and been viewed 2878 times.

LinkBack Thread Tools Display Modes
post #1 of 3 (permalink) Old 06-04-2009, 11:18 PM Thread Starter
Join Date: Jun 2009
Posts: 4
Points: 531
Thanks: 0
Thanked 0 Times in 0 Posts
4L80E Shift problem

Hope someone can help, been scratching my head for a couple days now. In a '99 truck, it start shifting out of first way late, unless you let off the gas. and the shift was harsh. Had the codes pulled and it said "Mechanical Failure". A guy I talked to said it could be the 1-2 shift solenoid or a problem with the valve body. Just to be safe we replaced the whole valve body with an AC Delco reman, and we still have the same prob. Short of the pump going out, there shouldn't be too much else that could cause a late shift, since the electronics control it all, or am I missing something?
rspasoje is offline  
Sponsored Links
post #2 of 3 (permalink) Old 06-28-2009, 01:39 AM
Senior Member
acesneights1's Avatar
Join Date: Jan 2009
Location: North East CT
Posts: 1,359
Points: 69,283
Thanks: 84
Thanked 126 Times in 121 Posts
VSS can cause this. It did in mine but it also threw a code for it. Check for historic codes.

1986 CUCV....M1008 6.2 NV4500 5 spd
Raptor 100 LP. Serp belt conversion. 5 inch redneck master exhaust. DB2831 IP. Dmax fan. Humvee waterpump.

1981 AM General M35A2c

Lee's Auto Ranch In Ellington CT SUCKS !!
acesneights1 is offline  
post #3 of 3 (permalink) Old 07-22-2009, 05:33 PM
Join Date: Feb 2009
Posts: 5
Points: 27
Thanks: 0
Thanked 0 Times in 0 Posts
Check the sensor and its connection closely before replacing it. Around 1350ohms both directions. Just got done chasing mine down after having the trans out, and completely tore down.
bullet2five is offline  

Quick Reply

Register Now

In order to be able to post messages on the Diesel Truck Forum - TheDieselGarage.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

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:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cummins to 4L80E richarr9 Diesel Conversion 5 02-04-2009 11:13 PM
SCT User Adjustments (WOT Speed Shift & Shift Pressure) ebusa 2003-2007 6.0 Tuner Forum 1 04-29-2008 04:23 AM
Do we defuel during the 1-2 shift or do I have a problem? imported_My427stang 2008-2010 6.4L Power Stroke 9 11-29-2007 12:25 AM
Transmission shift to reverse problem SGeorgiaMach 1994-2003 7.3L Power Stroke 0 09-17-2007 05:41 PM
4L80E tranny dieseldummy 6.5L Diesel Engine 6 06-04-2005 03:40 AM

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
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome