Transmission won’t go into drive or reverse

Zmac14

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Apr 22, 2020
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Make
Chevy
Model
Silverado
Year
1999
Miles
200,000
Engine
5.3
So I recently rebuilt the 4L60E in this 99 Chevy Silverado. We got it all put back in and started the truck and it will shift and go under load when going into reverse and drive but doesn’t move the tires ( we have it on jack stands) when we drop it to first it moves the tires just fine. My questions is, could this be the neutral safety switch or is it more likely a interal wiring harness issue? Or any other ideas? The truck has also been sitting without a battery for 2-3 months. Idk if that would hurt anything or not
 

billr

wrench
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Hmm, no help yet here. Are there no codes set? When you say it "will shift and go under load ", I assume that means the engine rpm drops a bit, as the TC turbine is being stopped by the trans gearing/clutches; correct? Do you have live-data available? Have you checked the line pressure? Have you disconnected the shift cable/rod and tried trans operation with the shift arm on the trans manually placed in the detented positions?

That's all just general stuff, now I will page one of our trans experts (BP)...
 

bp042665

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ok I just saw this so first off how well are you at building transmission ? I need some background history like what happen to this unit before you built it or reason why you built it ? I can help with more info
 

grcauto

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It doesn't move in 'D' but does if you drop down to 1st? If so, I would look at the manual valve.
 

Zmac14

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ok I just saw this so first off how well are you at building transmission ? I need some background history like what happen to this unit before you built it or reason why you built it ? I can help with more info
this is my first transmission so I’m not an expert by no means. We rebuilt it cause he lost all the gears and found out it was a sun gear. It does drop rpm when going into gear but I haven’t checked line pressure or pulled the shift cable
 

grcauto

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The manual shift is adjusting the manual valve. I'm thinking you have an issue with the wiring to the shift valves on the valve body. What does the scan tool show when in 'D'? What solenoids are on?
 

billr

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"...will shift and go under load when going into reverse and drive but doesn’t move the tires..."

That is from the opening post of this thread. Did I misunderstand, has reverse worked OK all this time? Again, no codes set?
 

Zmac14

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"...will shift and go under load when going into reverse and drive but doesn’t move the tires..."

That is from the opening post of this thread. Did I misunderstand, has reverse worked OK all this time? Again, no codes set?
No reverse or drive have not work at all since the rebuilt transmission has been put in.
 

Zmac14

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The manual shift is adjusting the manual valve. I'm thinking you have an issue with the wiring to the shift valves on the valve body. What does the scan tool show when in 'D'? What solenoids are on?
does the truck have to be running to check which solenoids are on in drive? I’ll have to check this next time im at The shop
 

billr

wrench
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Well, I think the inop reverse means this is not *just* and electrical problem; reverse is controlled entirely by the VB. We need one of the trans experts to confirm, before I get you headed out into the weeds. I'll ask one last time... are there any trouble codes being set???
 
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