Torque converter won't lock up
 

Hey guys just bought another 94 cummins bone stock 146,xxx miles. Truck runs awesome shifts great and rides smooth. But the torque converter is not locking up with the over drive on or off. I cleaned grounds and checked a few thing but not sure where to really look. Was also wondering if putting a lock out switch would fix the issue or if it wouldn't work at all. Any advise would be greatly appreciated.

when was the last time trans was serviced ?

How does the fluid look/ smell ?

if all this seems to be good.... you may have a solenoid issue .

We'll I'm not sure when it was last serviced I do plan on doin it. The truck did sit almost 2 years before I got it. But the tranny fluid is clean and does not have a burnt smell. So I kinda think it is some sort of solenoid. But I don't know where to look for that. Would a lock out switch work or would it do nothing

if the pump dosent get enough pressure, it wont lock up, ..

TPS, and Speed Sensors may also contribute to this issue, possibly.. not a trans expert .. But if it were me I would service trans just as a precaution either way ..

Ok thank you. I'm gonna do a service and hopefully it changed somthin

Yeah, Do keep us posted ..

Switch trans relay with ac relay worth a shot if not most likely lock up solenoid or converter itself

Well I changed the fluid and filter and wired in a lock out switch and still no lock out and I belive doin that would over ride the solinoid. I haven't tried switching the relay but I will if that don't work then I guess it would be the tc or valve body

If the TC is stock , I would vote to replace it first, But I would take t a trans shop and make sure thats whats really wrong .. I had to replace mine cause it was shot .... better mpg right off the bat

I am not being smart, but have you checked the wiring to the transmission? Make sure the wires are good and make sure the switch is actually plugged in properly. Trust me from experience here, a wire that looks good can be broken inside the casing and look good. Never assume before you have checked. If I am not mistaken the plug you are after is on the Drivers side of the transmission and really open to the crap under there.