Need some help. 48re problems...

SPEEDSHIFT

SPEEDSHIFT

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Jan 30, 2007
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The last couple days I noticed my truck started holding/ hanging up I'm 2-3 shift. Then all of a sudden today in traffic while sitting still in D, the converter locked and killed the truck.... So I start it back up, put it back in D, everything acts fine, it sits and idles fine in gear then starts to lockup again, so I put in in neutral and back in D and it acts fine for a while and just keeps doing the same thing over and over. Then I get out of traffic and start speeding up and it goes from 2 to OD locked... I ran it all the way to work fighting it with up shifts and converter lock.

Several times when the converter would lock I could get it to unlock by messing with my lockup switch. Like it would lock up and I would cycle my switch on and off and it would unlock, now it doesn't seem to work anymore.

All this has happened in the last 40miles. The truck has a cheapo billet single disk converter and a transgo kit in the VB.

I am going to try and pull codes here in a bit, remove the lockup switch, and check the electrical connections. See if anything changes.
 
No codes and it does have an upgraded GM gov pressure sensor.
 
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I wish it was just the converter locking up, but with it hunting gears and being on/off it makes me think electronics...
 
I went out and unplugged the round plug on the trans and it still does it. Put in in drive and sits fine for a little while then locks up and kills the motor. Neutral seems to restart it, but keeps trying to lockup.

It will not do it in reverse though...
 
When you unplug the harness, start the truck in neutral and bring it straight down to 1st gear and manually shift it 1,2,3 and see what it does
 
Ok, I went and did that... It shifted fine, didnt feel like the conv was locking through gears, slowed down normally. But whe I went to take off again, it felt like it staying in second then when I gave it gas it locked in second or third and bogged down. I did the "neutral restart trick" and it shifted fine to third. As I drove back to my spot, it stayed unlocked until I slowed down to turn in, then locked again.
 
SPEEDSHIFT said:
Ok, I went and did that... It shifted fine, didnt feel like the conv was locking through gears, slowed down normally. But whe I went to take off again, it felt like it staying in second then when I gave it gas it locked in second or third and bogged down. I did the "neutral restart trick" and it shifted fine to third. As I drove back to my spot, it stayed unlocked until I slowed down to turn in, then locked again.
Click to expand...

Converter won't lock until top of 3rd. ^ tells me you have an electrical issue not mechanical. I see my amish homeboy is viewing this thread now and will reign in with more knowledge! LOL
 
It has locked in any gear, like when it locked up just sitting in traffic and killed the motor.
 
SPEEDSHIFT said:
How could it be electrical if the plug was unhooked?
Click to expand...

With the harness plugged in it doesn't behave correctly. With it unplugged and manually shifted it sounds like it shifts fine? That points to an electronic issue to me, but like i said hopefully someone w/ more knowledge will chime in.
 
I guess ill pull the pan tomorrow and put all new electronics in it... IDK what else to do besides a new converter also. This is my DD, I have to have it running.
 
I fixed the tv cable and cut off the lockup wire with no change. I can start the truck, put it in and forward gear and it will sit and idle in that gear for about 30 seconds then you can hear it kind of start to lock up then release then completely lock and kill the motor.

Also, tow haul mode doesnt work at all anymore.
 
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To me, it seems like fluid is leaking past a valve somewhere and once it get enough pressure, it locks the converter. Then when I put it in neutral, the pressure drops, everything is fine until it builds up again... which takes about 30 seconds.

Thats my theory anyway. LOL
 
Do you have another valvebody you can swap in? I think you're right about a hydraulic leak. Check valvebody mounting bolt torque and also the torque on the screws that hold the halves together.
 
No, I don't. I am going to pull it out, clean it up, replace the solenoids, deck the mating services with some sand paper and check for warpage.
 
Well, I have about 40k miles on the Trans fluid and it looks like it's been 200k. Lots of metal on the magnet... The solenoids were pretty much blocked off and the screen in the VB was so stopped up it blew apart... I really don't want to have to rebuild this thing right now, as I planned on just limping it alone for a little and buying a 4th gen... I got it cleaned up with new solenoids and I will put it back in tomorrow, see how it does.


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