Trans acting weird. Son did power brake ! help !!

[yehaadon]

First let me say thank you in advance for taking a look at my problem. the story:

 

My son did a power brake burnout. when the wheels grabbed traction the spider gears took a crap. I fixed the spiders and that went ok, but, the transmission will not take off in od or drive. you can put the gear selector in l2 or l1 and immediately shift into od and it will shift up by itseld like nothing is wrong. it will drive perfectly , downshifting when slowing down, passing gear etc. it only acts up if you come too a complete stop. I can slow down around corners at the light or anything else as long as I dont stop. if I stop I have to shift to l2 ,just start to go then shift into od. any ideas will be appreciated.

[yehaadon]

Im not sur, how would I identify it. doesnt sound good huh? what is esp?

[TimmyG]

Im not sur, how would I identify it. doesnt sound good huh? what is esp?

what truck and motor

 

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[yehaadon]

2000 gmc 1500 4x4 4.8 motor.

[Chris]

Mileage on it?

 

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[yehaadon]

200,000 I dont know if this is actual on the trans. the previous owner was not hard on his vehicles. did his maintenace.

[Chris]

200k for a 4L60E... Your trans had a good life, lived longer than most. It was well past its prime and may it rest in peace. Time to just change it. a 4L60E over 100K can be a crapshoot of how long it will go past that. Very few 4L60's go past 150k.

[yehaadon]

If you start out in l1 or l2 and just start going, and then shift into od , even at 10 mile an hour it shifts and pulls normal. it only acts up if you get below 10 miles an hour or stop completly. then you shift into one of the low gears , start out and shift into od. only starting out is problematic. it downshifts in town at slower speeds, shifts into and out of passing gear on expressway, does not slip or anything. drives normal except when you stop.

[aflesch]

Shift B solenoid has failed or the spool valve controlled by it is stuck.

[yehaadon]

spool valve.......? valve body? Can I try to fix that ? I am not really up to speed on hydraulics, but I have seen tractors with hydrospeed that have been towed , messed up because too high of pressure expanding the spool ? sticking? If the spool was bad , doesnt it seem as though it wouldnt shift ? I really have basic knowledge of hydraulics so this is not educated , Im just kinda trying to remember stuff Ive read in my life, LOL. If I am right I remember valve body work was akin to surgery in cleanliness! too much for me to try ? I watched my father rebuild many transmissions as a young man. he was a transmission guy, speacialized in hydraulics. (Bell forklift) I am not ignorant but not educated either.

[aflesch]

You should really take it to a tranny shop and have that diagnosis confirmed before you tear into anything. They will have a 2-way scanner that they can test the functionality of everything before taking anything apart. I think it will be worth the $80. If they confirm the Shift B solenoid failure you could easily replace it yourself.

[aflesch]

The Shift B solenoid must be energized in OD First or an internal hydraulic crossfeed results preventing fluid pressure from building in the forward clutch apply circuit. The Manual First and Second gear selector positions uses different hydraulic passages (and clutches) than OD First and second. This allows the vehicle to start moving. Once you shift back to OD the PCM commands Second gear and the internal crossfeed no longer exists. When you are slowing down below 10mph the PCM commands first gear again which once again results in the internal crossfeed and releases the Forward clutches.

 

I know that's pretty technical but it explains why the transmission will shift normally in OD once you are out of first gear with a failed Shift B solenoid.

[yehaadon]

Aflesch, thank you , thats the detailed info i was looking for. I like to be informed when I go get it fixed.

[yehaadon]

I have heard that there is a fuse going to the shift solenoids. where are these located ?

[aflesch]

You are correct. I am not sure where it is on your truck. It only takes a minute to check them all with a test light though,