I"m at wits end,here..I have an 85 gmc van,with the 700R4 trans.,and had the common"Will Not Up-Shift problem,with it.I replaced the governer,dropped,and cleaned the valve body,and replaced the o-rings,and all seals..After 2 different TVI cables,It still will not shift out of first,until I floor it(all other shifting,is normal)..Did I miss anything!??

Asked by Nov 17, 2012 at 12:10 PM

Question type: General

3 Answers

710

try the trans modulator or check to see if the vacuume hose going to it has some kind of leak. also can start up truck pull off vacuume hose at trans modulator to see if it's spitting out fluid if it is it's gone.if it's not going into 1st check this out. besides thier about $10.00. if you do change it be sure not to loose the pin that goes in the middle when you pull it out. new ones don't come with a new pin

I wish,it was that easy,but,the 700R4,has no vacuum modulator..all shift-points,are controlled inside of the trans.,by the tvi cable(down-shift/up-shift),and the governer..Usually,The repairs I mentioned above,cures the up-shift problem..Now,I have to figure as to why, I have to "floor it" to get it out of 1st gear..Thank you,for answering,though..I wish it were a turbo 350/400,,It would be the modulator.and would be an easy fix...

Also, I did the high-line pressure test..The pump is fine(125 psi,at idle,,105-135,in drive)..I pulled the tvi cable,pulled it out to maximum(held in place,with needle nose vise grips)and it shifted fine,through all the gears-with the exception,of trying to go into passing-gear(expected)..put it back together,and same scenario..going to pull pan,tomorrow,and check for debris..I"ll keep you posted..

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