2005 built 48re lock up problems

ThunderedRod

ThunderedRod

Hot Pants
Joined
Mar 13, 2012
Messages
152
Built 48re from Firepunk diesel. No warrenty because it was a Garmon unit that broke a shaft. Firepunk went through it and put in new clutches, cut cleaned the TC and put in a Firepunk comp 1 VB. Just started having this lock up problem. Only when the trans is warmed up. Trans temp 120-130. Haven't dropped the Pan yet to take a look. About half way through the video I turn on the TC lock up switch and it stays locked up. Then I turn the switch off again.
Does this on both UDC and Smarty canned tunes.
I haven't had a chance to call Firepunk about it yet.
Any ideas?

[ame="http://www.youtube.com/watch?v=GK3d62QVhlU"]http://www.youtube.com/watch?v=GK3d62QVhlU[/ame]
 
main Harness to lock up solenoid and transducer sometimes goes bad! Usually fries the transducer but yours looks like lock up wiring.
 
Just had a thought... I'll have to check after work to see if it's true. Was reading a few places said the where VB wire harness comes up through the trans and plugs into the truck side harness. That seal can break and allow trans fluid to come up into the plug. I also noticed my trans fluid being a too high from the last time I changed it. So hard to get a good reading. Hopefully this is what's going on.
 
It looks like lockup is still a solid engagement, but it bouncing on/off causing rpm fluctuations, first check the connection on your truck where you tied in your lockup switch, a bad connection will give these results, next Clean the 8pin connector with brake clean and compressed air, and If the problem still exists, it's possible it's the actual solenoid is bad or the vb wiring harness is shafing or pinched.

Lavon
 
Thanks Lavon!! I'm going to clean the 8 pin and get my trans fluid to a lower level and see if that helps.
 
Took fluid out to a respectable level on the dip stick. Cleaned the 8 pin with electrical cleaner. Took it out for a test drive it was good for about 10 mins then it started to have issues again this time much worse. What felt like all gears were jumping in and out slamming. Hooked up the lock up switch, this time it didn't fix it, it just made it worse. Got a code as well P0720 low speed output rpm below 15 mph, not sure if that's the right discription but I know that's the numerical code. Tomorrow I'll drop the pan and see if I notice anything strange. Any ideas on what I should look for?
 
Change output shaft speed sensor, it's best to diagnose with a scan tool but if it threw that code it code easily be the output shaft speed sensor dropping signal

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Changed out the output sensor. The one I pulled out had a decent bit of fiction material on it. Not sure if that had something to do with it or if that's normal. Drove the truck for half a hour and got the trans up to about 140. Everything is good so far! Thanks again Lavon! You guys build a great trans!!
 
Yes it's magnetic, not uncommon for it to pick up Slag, sounds like that was the issue

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Hey lavon, while we're talking about lock up issues I've been having an issue with my converter not wanting to lock up with the switch under heavy throttle in third or od. It locks up fine in I lock it up in first or early second gear. Could this possibly be a solenoid issue? I have your comp3 Vb and an ats converter that was rebuilt by dpc


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I can't get my trans to lockup in any gear.... new harness, solenoids, lower part of valve body, and even sentry the con veteran to dpc to be cut cLea ed and fold theresults nothing wrong. I've tested my switch circuit with power to trans I have power to the incoming side of the switch like a circuit should with no ground. Hit the switch and ground it and the power goes away that was with the old solenoids and valve body I haven't tested that with these new solenoids. This is all on a trans with about 70 miles on it and couldn't ever get lockup to work. Idk what else to check...
 
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