4l80E converter aggravation

[phantom309]

it locks and unlocks when it feels like it,.will stay locked for a long time,. then unlocks and stays for a while then locks etc,. etc,.
why??
would adding the manual lockup switch fix it? or is it a prelude to a dying trans??

nick

[suburbanK-2500HD]

Have you checked the brake pedal switch.
On my 1994 TD, it unlocks when activating the brake light, and locks when releasing it. This is happening in the speed when it locks naturally, about 80 km\hour.

In what speed does this happend to your truck

[phantom309]

good continuity on the switches,.adjusted fine etc,.
it has no particular speed or particular throttle postion etc,..
has any one else had this kind of problem??

Nick

[JohnC]

If it unlocks when it "shouldn't" it will set a code. If no codes then the PCM is commanding it to unlock. Coolant temp sensor or brake switch are two common causes. Does it drop out of cruise? (brake switch) Missing brake pedal return spring?

[phantom309]

well john C thankyou sir,. the temp sensor was busted and just sort of 'pushed' together,. so it was all over the map as far a temp goes,. i did notice the other day it had high idle while sitting at a light,. then it 'calmed down'

thanks eh??
my cruise has never worked,. mebbe it might now??

now have to do rear brakes,. aaaargh,..

nick