Anybody know the part number for the Thermal switch in the 700R4?
Not sure on the year cuz its a B & M unit.
Been trying to figure out why it won't lockup except in 4th.
Does the thermal switch only interrupt the ECM controlled wire?
Not sure if the black sol wire (gnd) is t'd at the thermal switch.
Must be if the lockup happens in 4th all the time but not in any lower gears.
Have seen conflicting info on this because there are website saying it keeps the converter from locking unless the trans fluid is above 180 deg F but when you look at any of the lifespan charts, 180 is the most heat you want for long life.
I run an external cooler anyway and am wondering if I'm keeping it too cool causing it not to lockup or the switch is just bad.
What are the downsides of jumping it out?
TIA

 

You'd have to ask B&M for the part number. The factory thermal switches I've seen in some 700R4s were all to lock the TCC when the fluid was hot.

If you're still running an ECM you probably don't need to worry about the switch, the ECM won't lock the TCC until the coolant temperature rises. Hard to say though, because that thing doesn't necessarily have anything like the factory wiring in it.

 

Guess I'll do some probing around and just make it work the way I want it to.