Engine/Transmission (1994 - 1998) Mystery Switch

[Dallass]

I know that when you install the mystery switch, that you should remove the transmission relay and put in a jumper. WHY? I left the relay in after having problems with the transmission that the trans shop put in new governor solenoids & seems to be working fine when I use the switch to lockup the TCC without putting in the jumper.

 

[Dieselnerd]

It will work fine most of the time but there are conditions where the relay drops out and then you also drop out of lockup. I had a TC unlock switch as well as lockup on my 12 valve and with the relay in it would go to limp mode (3rd gear starts) whenever I unlocked the TC. To get out of limp mode I had to turn off the ignition and then restart the truck. With the relay jumpered out it always worked fine.