Tranny help (lockup problems)

[yukonjon]

Well I took your guys advice and took the truck to 2 different tranny shops. They hooked up all the computers and ran all the tests. Both shops cant find anything wrong. Now I stuck on what I should do.

Basically my torque converter is coming in and out of lockup at speeds between 40 and 70 mph when a light steady throttle is being applied. Does it most between 40 and 50 mph. Sometimes it does as much as every 3-5 seconds while cruising. Changed or tested the TPS, map sensor, PCM, speed sensor, tranny, brake switch, etc. This is a new mega-monster transmission from Monster Transmission. I don't know weather I should just let it be and keep driving or is there something me and the shops are missing. I'm afraid to cause damage to the tranny even with the shops saying everything's working. I know this isn't normal. Just seeing what you guys think or if you have any recommendations.

Also, I just sent my PCM back to BBP for a retune and have the stock one back in it but it didn't help anything. Is it possible to tune the computer to have the tranny only come in and out of lockup at different times. Ex: between 45 and 55 mph only or something else I could change. Thanks for the help guys.

 

[lestat0669]

I have the same problem.... but I was told that I needed to replace my torque converter. My transmission was rebuilt last year and this problem started like 3 month ago. Finally after reading and researching this and told by two mechanics. Their solution is to replace the torque converter. I havent change mine........weather not very nice but will when weather permits. Hope this helps. my transmission is a stock 4l60e

 

[04SS99Denali]

i had this exact issue with my 99 denali. my converter would constantly lock and unlock when between 45-70. the truck sat 1.5 years untouched prior to me owning it so i wasnt surprised. i just changed the fluid and it stopped doing it.

 

[yukonjon]

I'm just hoping it's not the torque convertor. Any speeds other than 40 to 65 it seems to work perfectly. I currently have synthetic fluid in it and I thought I had seen somewhere that it might cause this problem but I'm not sure. Any ideas on that. Anyone know if this will cause damage or whether i could change the computer settings.

 

[brooks93]

Mine was doing the same thing. Then I noticed it would kick out of cruise if I had it on at the same time. I ended up being a 10 dollar brake switch. The switch is located on top of your break pedal and is a pain to replace but, I haven't had the problem since

 

[yukonjon]

Yeah, already did the brake switch. Was hoping it would fix it but no luck. Mine will do it in cruise with no problem in both 3rd and 4th gear. Im stumped on what it could be.

 

[Jaycenk]

Do either of you have custom tunes done to the pcm?

 

[yukonjon]

I do have the custom Black Bear Tune but it hasn't changed anything on what my transmission is doing. I have the stock one back in right now just to eliminate any PCM problems. Has the same problem with both PCM's.

 

[Jaycenk]

I would just unplug the pcm harness at the trans and use a LITTLE of dialectic grease and make sure you plug it back in all the way. Those plugs have been the source of many problems that can not be explained. Some times simply unplugging it and plugging it back in fixes the problem.

 

[steamroller]

Probably the TCC (torque converter clutch) solenoid since you've replaced the brake switch, or it may be a loose connection like already mentioned. I would call up the guys that ''built'' it and see what they say.