C-4 transmission slides between 2nd and 3rd under light acceleration

Based on the symptoms you described, it is possible that the issue is related to the valve body of the transmission. The valve body is responsible for controlling the flow of hydraulic fluid through the transmission and is made up of various valves and solenoids that regulate pressure and flow.
When the winter drive is engaged, the transmission may be bypassing the valve body and locking into third gear directly, which would explain why it starts in third gear when winter drive is engaged. However, the hard shift from 2nd to 3rd and the inability to shift into 3rd without winter drive suggest a problem with the valve body.
It's also possible that there could be a problem with the transmission control module (TCM) or the wiring and electrical connections between the TCM and the transmission. A diagnostic scan tool can help identify any error codes or other issues related to the TCM.
Given that you have already replaced the 2nd to 3rd shift solenoid without any improvement, it may be best to have the transmission inspected by a professional mechanic or transmission specialist who can perform a more thorough diagnosis and determine the exact cause of the problem. They may also recommend a rebuild or replacement of the transmission if the issue is more serious.

Hello. It seems your vehicle's transmission has to be rebuilt/replaced. Any automatic transmission that won't 'shift' from 1st gear into 2nd or 3rd gear has a 'worn' slave cylinder that 'slides' gears one way or another. 1st gear works yet 2nd and 3rd don't. Good luck and keep me informed; if you want to.

Governor pressure controls the 1st and 2nd shifts. After that is the 3 and 4 solenoids. you would need to look at the pressure when driving(takes a scanner). pressure is 20 to 30 PSI from 1st to 2nd, depends on acceleration. After that the pressure will jump to 100+ psi. Did you replace the governor solenoid and sensor? They are on the passenger side of the transmission and sit in a block that detaches from the valve body.

Auto Trans not shifting correctly from 2nd to 3rd - Ford Explorer ...

www.explorerforum.com > ... > Under the Hood

May 8, 2004 - 19 posts - ‎9 authors
Auto Trans not shifting correctly from 2nd to 3rd Under the Hood. ... Become an EliteExplorer. Lithuania. 1999 5.0. Join Date: Jun 2003. Posts: 107 ... When this happens, the transmission will skip to the next gear like you said.

Transmission Harsh shifting - YouTube

? 3:59
https://www.youtube.com/watch?v=aAoiL4vR8Qw
Jan 13, 2013 - Uploaded by James Burns
... Doctor, explores the causes of harsh shifting in automatic transmissions. ... Early diagnosis is important to ...

Hard Tranny Shift between 2nd & 3rd - Ford Truck Enthusiasts Forums

www.ford-trucks.com > ... > Super Duty & Heavy Duty

Feb 24, 2012 - Hard Tranny Shift between 2nd & 3rd Super Duty & Heavy Duty. ... I just got a new to me 99 f250 5.4 V8 SD XLT 4x4 Auto Trans longbox 118k miles. ... it out and said it was solid except for a hard shift between 2nd and 3rd gears. ..... Hard shift between 2nd and 3rd, Brenda Lamka, Explorer, Sport Trac, ... hard shift 2nd to third gear only 4r100
Dec 26, 2012
hard shift into 3rd
Nov 4, 2009
4r55e 5r55e Ranger / Explorer Transmission Problems - CLICK ...
Mar 15, 2007
00 Expedition trans shifts late and hard

1 Ck A/T fluid level & quality
2 Scan/ck for code(s)
3 With scan tool connected,road test vehicle/Ck parameters....
....time for a pro !!

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Check the transmission computer

Hopefully this Transmission is still under warranty?
If its a stick the shifter or schronizers could be the culprit. If the vehicle is an automatic,shift solenoid, shifter, problems in 2nd and 3rd circuitry (band or clutch not releasing properly ),manual shift valve .
Take it back to whom ever did the rebuild or transmission work tell them the problem .
Business is so demanding these days they will probably do the right thing.

Vacuum modulator on side of transmission and/or the line connected to it my have a leak to begin with. After that try replacing the pistons on the side as they are inexpensive in comparison to a transmission rebuild. If you do go with a rebuild try buymbparts.com or autohausaz.com for rebuild kits.

they did not install bands right needs to be rebuild bands need to be adjusted