47re won't shift out of first

madmikeismad

madmikeismad

So mad
Joined
Dec 19, 2009
Messages
14,347
Manual valve body.

Ran truck out to about 3k rpm tonight and it refused to shift out of 1st gear. Still have reverse. Fluid level is right in middle of hash marks, still red and not burnt. Everything is fine except for not shifting out of 1st.

Any ideas?
 
Just tried something. If i turn the truck on and shift super fast into 2nd, i can start in 2nd. But as soon as I down shift into 1st, its stuck there. Read somewhere that might be pressure sensor?
 
Output shaft speed sensor or governor pressure sensor! If you unplug the main connector, round plug, at the trans, you will have 1st, 2nd, and 3rd by manually shifting. Come to a stop and go neutral back to first to get it back in first. Output shaft speed sensor is in the tail housing and can be changed in about 15 minutes, Governor Pressure Sensor is on the valvebody
 
CPSimpson said:
Output shaft speed sensor or governor pressure sensor! If you unplug the main connector, round plug, at the trans, you will have 1st, 2nd, and 3rd by manually shifting. Come to a stop and go neutral back to first to get it back in first. Output shaft speed sensor is in the tail housing and can be changed in about 15 minutes, Governor Pressure Sensor is on the valvebody
Click to expand...

Not to doubt you, but how sure are you? Money is tight this month, especially trying to make finals LOL I'd like to buy something and have it fix it the first time LOL Is there a way to narrow down which sensor it could be? The speedo still works (don't know if that works off that speed sensor or not).

Also, thanks for the fast response this late at night!
 
I should also mention that a few times in the last few years, if I let the rpm's get too high, it won't upshift until I let off the throttle some, then it will shift and I can get back into it. I was assuming it was making too much line pressure, and making something not work right until I dropped rpm/line pressure a little. Could that have been a precursor to the pressure sensor going bad?

If it is the pressure sensor, is that the piece thats able to be replaced with the better GM part?
 
you say it is a manual vb? shouldnt be any of the sensors, or computer then.
 
The electronics shouldn't really have an effect on it. But if you unplug the main plug and the output speed sensor you should be able to shift it. If it still doesn't shift I would temporarily remove the tv cable and try it again on the jack stands.
 
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Mike, when my OSS sensor was bad it would still shift to second, it was just hard and wouldn't happen until @ 20mph. It would only do this the very first shift and after that it would upshift fine until you shut the truck off and restart and then it would do it again on the first shift. OSS sensor is @ $17 at O'Reilly if you wanted to try it but I doubt that's your culprit.
 
If you had access to a scanner would also help so that you could monitor the oss
 
Sorry Mike, I missed the manual valve body part. Everything I told you doesn't come into play.
 
Ok lol. Well at least i have somewhere to start. I really hope i don't have to drop the trans
 
So i unhooked the harness. I have all 3 gears back, upshift and downshift fine.

So how do i narrow down which sensor it could be?
 
If it is a true manual VB, disconnecting the electrical should do absolutely nothing with the 3 forward gears.
 
That is what I was thinking. I have nothing (harness wise) hooked to mine and it does what I tell it to.

So if yo uunhooked everything and got it working, I woud guess the computer is over riding something.
 
I don't know what makes a "true" manual vb, but it was an oem vb, and has been modified a few times, ending as a manual.

Can i just cut the wire for the pressure sensor in a repairable spot? That way i can keep the harness with lockup and od.
 
I would look more at the gov solenoid than the sensor. If you pull the trans relay, you will lose lockup and OD, but that would be able to allow you to test a theory, to see if the gov solenoid is doing something.
 
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