Transmission not shifting

1995 GMC SIERRA
138,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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MATT_NEWWBEE
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I have a k1500. My transmission will not shift unless red lined. First to third. Skips second and haven't tried for over drive. When I go from park to reverse, neutral, drive etc. Reverse the little marker goes away, neutral is drive, drive is third, third is second. There is no 1 option. Any ideas? No check engine light. I'm at a loss for ideas on what to do.
Apr 24, 2019 at 8:57 PM
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KASEKENNY
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Hi Matt,

It sounds like the shifter is out of adjustment if I am reading this correctly. This can cause shift issues because the manual valve in the transmission is not seated in the correct location which will not direct the fluid to the correct location inside the transmission.

Go through the adjustment procedure first and then retest the transmission. If there is still an issue we can go from there. I attached the procedure for both transmissions because I don't know which one you have.

Let me know if this makes a difference or give me a little more info if I am not reading this properly. Thanks
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Apr 26, 2019 at 4:59 PM
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MATT_NEWWBEE
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On my transmission where the linkage is. It is angled more at a angle like this, but there is also a black box behind it, but I didn't see one in the pictures. Upon research I believe it is a neutral safety switch? It is either a 4l60 or 4l60e but pretty sure it is the E model. Do I just undo the cable and move that little black bar that hooks up to the cable? I'm sorry I'm not too familiar with this.
Matt
Apr 27, 2019 at 6:36 AM
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KASEKENNY
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Check out this video. This is on a 1998 but it appears the same as yours. Hopefully this will get it taken care of for you. However, this is a pretty common issue on trucks and the GMC does not illuminate the selected gear when it is out of adjustment. In this video he mentions his P did not light up and the truck would roll. Doing this adjustment fixes his and I am confident that you will have the same result.

https://youtu.be/Au61yOGhDUY
Apr 27, 2019 at 10:53 AM
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MATT_NEWWBEE
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I will give this a try and come back later with updates. Thanks again!
Apr 27, 2019 at 11:06 AM