TC unlocking randomly

[Highridge]

Hi guys
I just put in a new E4OD in my truck about a week ago and replaced the FIPL about a week before that ( black one from autozone) Now whenever I am driving between 60-70 the TC will randomly unlock itself and the rpms will jump about 300. This cant be good for the TC (new) or the new tranny. Could this be because of the cheap FIPL i put in or maybe the brake switch? Is there any other switch that controls the TC?
Thanks,
Derek

 

[bobracing]

http://www.oilburners.net/forums/showthread.php?t=11472&highlight=lock-up

 

[Shadetreemechanic]

That happened to mine and it ended up being a bad tach sensor. Have you had any problems with your tach?

 

[Highridge]

The tach works perfect. Is it possible for it to send a bad signal to the trans and still have a good reading on the dash?

 

[topgunn]

Any problem with brake electrical system can cause it. The TC is connect into brake system. It can be as simple as brake switch. Cruise control also controls TC lock-up, I had same problem for years and found brake wire under bed that was shorting now and then. Hope this helps.

 

[LCAM-01XA]

I'm thinking brake lights circuit issue as well...

 

[Shadetreemechanic]

The tach works perfect. Is it possible for it to send a bad signal to the trans and still have a good reading on the dash?

Yes. With mine I thought the tach was working perfectly, but after having it pointed out a a possible culprit for the tranny, I noticed that it would read 200 or so RPMS higher at idle when my torque converter was acting up. The brake light theory is a good one to explore as well. If you want to try the tach idea, just take the sensor loose and wipe the end of it clean and reattach. Often there gets to be a buildup of oil on the sender that interfieres with the signal.

 

[Highridge]

Thanks guys
Ill try cleaning the tach sensor and see if that helps. I'm thinking it might be my backrack which has brake lights on it, maybe a grounding issue.