TH200R4, non-working lock-up

[TorK]

Hi!
I am new on this forum, hoping to learn a few things about my '88 Monte Carlo SS.
My trans refuses to lock up the converter. Somebody has also removed the cruice control unit. Could there be a connection between the missing cruice control and the missing lock-up?
Any other suggestions??

TorK
Norway 😀

 

[GT_80]

There could be a connection between the two- I think the lockup used to run through a vac switch on the intake and the cruise control module as well... There was a diagram on here along time ago, I can't remember where it is... The plug on the trans can be wired to a toggle switch for lockup on command or do a search to Torque Converter Lockup wiring diagram

this should be similar- from a 1980 Vette manual

 

[G-Body_Vet]

The most common issue with converter lock-up is the TCC solenoid located on the transmission valve body. I've experienced it with the converter not wanting to disengage , but not with it engaging. I'd start by making sure your plug on the side of the trans is connected. I'd also research how to troubleshoot it properly before making it a guessing game or throwing money at it.

 

[King_V]

Here's one potential simple cause: bad thermostat.

I believe the minimum temperature the computer will allow the lockup to engage is approximately 140 degrees F. If the coolant is not getting to that temperature, the computer will not engage the lockup.

I've had a car that had this issue, and my dad had a car with the same issue.

Your Monte is a 1988, yes? Is it still running the full computer system, sensors, etc?

EDIT: Hmm, the diagram for the Corvette says 130 degrees F . . I'd always heard it was higher. Well, in any case, temperature is something to consider!