Question about 1991 Chevrolet C1500
My 1991 chevy pickup with automatic tranny is not shifting into 3rd gear. Fo a while it helped to turn the ignition off and restart but now that does not always work. Does this system use a vacuum modulator or would this be a TCM problem? Where is TCM located? Thanks in advance for any help. Chuck
Tha vacuum modulator will not keep the truck from shifting,it only helps with sift quallity.it sound like you have some internal problems and will need to take it to a transmission shop
Posted on Jan 02, 2009
need more info i had a 1984 chevy half ton and first, second, and third worked fine but lock up didnt work. the problem was there was no vacum at a switch under the hood on the fire wall also your shift linkage could be out of adjustment. try driving down the road and raise up a little on the shifter.
Posted on Jan 25, 2009
The shift shaft has stuck. The modulater shifts threw all gears so if you pull the hose off and there is no fluid leak then the modulater valve may be good. You could try turning the adjusting screw inside the vachumm hose and if that does not work pull the oil pand and lube all the shift solinoids they may have rusted fron condensation. Use a screw driver to get it to move the shift levers and buy some lucas trasmisson oil and run it in there it will soften the seals. Hope this helps.
Posted on Jul 09, 2009
common problem. It will need rebuild or replacement. They are common tranny's do due this, there are many out there and reasonably priced.
Posted on Oct 06, 2009
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