transmission slipping
 

ive posted on here a few times, so this will probably be the last time until i get the truck fixed, then ill let yall know what the fix was. (i dont want to be annoying) and i already searched through this forum and didnt find anything similar to my problem, well, there was one but the post stopped.

1998 chevy blazer LS 4x4 4.3L 4dr automatic

first of all, if i let the truck WARM UP there is a delay when i put it in drive or reverse. it rolls a little but it will go into gear.

if i get in the truck and just take off it shifts great, but when it warms up down the road its start slipping or just not shifting at all. (i dont know which). and the rpms rev up. most of the time it will read: 60mph 2000rpms. like it wants to shift but just doesnt.

(this part is what i dont understand) - if i pull over and cut the truck off then immediately cut the truck back on it will shift fine again but only for a few minutes.

cold: shifts great
warmed up: slipping or not at all

atf was disappearing. when i removed top plug on t-case atf poured out. so i replaced the vacuum switch. i didnt replace the input seals from the transmission to the t-case yet but after i filled the atf to its proper level atf isnt disappearing anymore. (so says the dipstick). so maybe i dont have to replace the seals?

i blew two of the three vacuum lines out. the third line i didnt blow out because i have no idea where where it goes. but if there is atf in the line that i didnt blow out would that cause my transmission problem?

i did get a code, it was p1870, i was told it could be anything from low atf to the rebuild of the transmission. by the way, there is NO hard shifting or any noise at all. no grinding, clanking or whining just slipping or not at all. (honestly i dont know what slipping is, it could be slips or its just not shifting at all).

ive been all over this forum and the world of google. at this point i dont even know what my question is anymore. so if someone trips over this post and may know a thing or two about this issue please let me know. thanks

Actually there was a case on here within the last two weeks with almost identical symptoms.. minus the atf>transfer case knowledge.
oh, wait that was you.

How many threads you gonna do on the same problem.. nothing wrong wrong with a nag-bump.
established that it's likely an electrical problem

Referring to this post with schematic attached
https://blazerforum.com/forum/engine...e2/#post502737

Did you do either of those things?

Did you at least pull the harness connector to the trans and clean it up and inspect it?

If you could rig a DVM to pins 6 and 16 here, that might tell you something.

https://blazerforum.com/forum/attach...iew_pcm_c3-jpg


https://blazerforum.com/forum/attach...ift_sols_r-jpg
That's a variable voltage but if it's different when it slips than whe it restasrts/reset, that would point ot either a short in the pressure solenoid or weak driver in the VCM

yes, i replied back to you asking you what do you mean by pink wire?

no, i didnt replace the sol. because i read everywhere that if it was a sol. then there would be a specific code for that. i cant remember the code but it wasnt p1870

all the wires are connected firmly in the pcm and there is no corrosion. thats what i was told to look for anyway. loose wires and corrosion.

no, i didnt pull the harness connector for cleaning. i didnt know do to that. is this harness inside the pan or outside? i see some hookups on the outside but dont know what they are. nothing appears broken or craked. when im inspecting the harness, what do i look for? just dirt or something?

sorry about the misunderstanding but i did reply back to you about the pink wire and then later i found out sol. have there own codes apart from p1870