Question about 1988 GMC G2500

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1988 GMC Vandura 2500 w/ 350 5.7L Auto Trans prob

My van will not shift up out of 1st gear. It can be pused up to 45 mph but will not shift into second. There is no slippage of any kind nor any burnt smell. We were thinking it was a quick and easy vacuum modulator fix but to our surprise there is not modulator clipped to the side nor attached inside the transmission. Could it be possible that an 88 model would have electronic sensors or solenoid? IF so do those need to be replaced or would it be someting with a fuse or an ignition switch issue?

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  • trollusk Feb 23, 2009

    Asking around via phoning local transmission shops, I was given answers ranging from a broken gear in the governor to a broken or hung cable to a clogged filter (the latter I know is not the problem. The filter looks fairly new and clean). What do you all think?

  • trollusk Feb 23, 2009

    Further info:



    We took the van on a weekend round trip that went about 900 miles. It drove just fine. The night after the trip, we went to town and it started the no shift problem. We pulled over and my fiancee parked it and put it back into drive thinking that perhaps she didn't quite have it in gear. When she put it back to drive and pulled off it worked just fine. The next morning it started doing the same thing and by the time she picked me up from work that afternoon it wasn't shifting up at all, no matter how many times she pulled over and put it in park then back in drive. We live about 15 miles outside of town, so it was a very slow drive back. In other words, it seemed quick but not sudden. It acted up for a day or so but would work fine for a bit. (that next morning when the van was able to shift to 2nd and so on, it would act up again whenever we stopped at intersections). I hope all of this info can help clarify what the issue may be. Thanks

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Hi my name Alex, Am looking to see in wich way i can get a copy of the Vacuum Schematic for a 1988 GMC Van 5.7L V8

Posted on Dec 30, 2010

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