Lock up question
 

Just bought a 99 2500 auto about 1 month ago. Seller had the transmission rebuilt about 1 year ago but has not put many miles on it since. Seller said he had a heavy duty torque converter put in it with a shift kit. Now at about 45mph when the tranny goes into lockup it will pop out on lock up and back in. It doesn't do it once I get up above 50mph. When it started it seemed worse when I hit a bump. Does anyone know what could cause this? I have been told it could be a ground wire problem.

electrical problem, selinoid problme, its hard telling with the amount of electrical these trucks use

take it out of overdrive. your not going fast enough to maintain

Even with OD disabled it does the same thing with lockup in 3rd gear.

check tps sensor, these are know for causing erratic t/c lock up concerns. also i have a manual switch on mine and hd convertor i can lock it up around 35mph but it causes the truck to buck untill around 40ish mph.

Clean every ground in the enginer bay. Make sure all the connections to your batteries are corrosion free. Ensure you have a solid ground to engine, engine to chassis, etc.. Inspect every ground. One bad one can cause a ground loop which introduces noise into the circuitry and can confuse the trans. There are 3rd party workarounds to proper gounds (DTT sells a noise filter) but a lot them have been fixed in the past with just making sure all grounds are sparkling clean and sound. Good luck and report back.

if u call geroend transmission he has a noise filter tell him ur problem and he might give you one for free. my dads truck did it and he told him sent us one no money asked or questions. the my cuzzins truck did it my dad called again no money or questions asked sent another FREE. so try it.

Thanks for the replies, I will check all the grounds first and see if that does the trick. Do any of you know how to reset the TPS, I have heard that you disconnect the battery cables and drain electrical circuit, then switch the key to on/off 3 times, stopping in on position and depress the pedal slowly. Is this correct? Thanks

i think all you have to do is turn the key on engine off. slowly depress accel to the floor and back up. this procedure doesnt correct any issues with a faulty or erratic sensor. it is just a procedure for the computer to learn the limits of the tp from idle position and wide open throttle.

Well I just cleaned all the grounds that I could find and cleaned the terminals. Time for a test ride.