is there any chance that the pwm solenoid could be causing this? I read this on the internet... 95 blazer no tcc lock up - Auto Repair Forum




seems like the problem im having. so I called the mechanic and asked him if he replaced the pwm solenoid and he said no. so I asked him if he could replace it. so I will take it down next Tuesday and get it replaced. i hope this is it.

 

got the truck back from the shop today and he replaced the pwm solenoid. still no change. his shop is located on the highway. when the blazer is cold and I get on the highway at 45mph it locks up like its supposed to. and when it hits 55mph its still locked up. I can confirm by putting my foot on the brake lightly then rpms go up then let foot off rpm drops down again. BUT after about 30 seconds to a minute goes by it comes out of lockup and never engages again. sometimes right after it comes out of lockup I can get it to lockup again by pressing my foot on the gas a bit harder then letting up on it. it will go back into lockup by doing this but only for a few seconds. then after trying again again it wont ever go into lockup again. then when I get back into the city 2nd and 3rd shifts are really hard. max line pressure. but when the truck is stone cold and im on the highway it seems to lockup but only until it warms up which isn't vary long. so im thinking when the computer goes into closed loop it seems I have no lockup. idk just a guess.

 

does anybody have any other ideas?

 

well I decided to hook up a toggle switch to the tcc lockup solenoid. but with the pwm solenoid in the way it wont let fluid to the tcc solenoid. so Im going to have to drop the pan and either take the front oring off the pwm and cut a notch into the solenoid to bypass fluid. or stake the isolator valve in place. which would be better of the two. I would really like to fix the problem but nobody in this world knows how or whats wrong with it. so I have to manually control lockup or its going to burn up in no time.

 

well guys I got some good news and bad news. the good news is I got lockup to work by staking the isolator valve in the full open position


the bad news is it will come out of lockup on the highway after about a half mile when fully warmed. when lockup slips out I can push the gas some more and it will lock again. I can do this maby 3 times then nothing.


I have put in a toggle switch in to manually control lockup awhile back.


but since I staked that valve it now lets me control lockup manually. but only after the computer has set max line pressure when it fully warms and after computer kills lockup. then I have hard 1-2 2-3 shifts.


so basically I only have manual lockup control when the computer sets max line pressure and denies lockup.


any ideas?

 

replaced harmonic balancer today. still vibrates.......