47-55.1 700R4 Brake light switch?

[1project2many]

Hmmm... My apologies. I just realized that I implemented the 4th gear switch incorrectly. And you're correct... no 4th gear switch in the article either.

A single relay and a jumper between A and C at the transmission (using the diagram in the article above) would allow a single relay circuit with brake switch cutoff. I have never had a problem with the 4th gear switch failing, but anything is possible. A relay based circuit to protect the 4th gear switch would look like this:

Relay 1:

Terminal 85 Brake lights
Terminal 86 GND
Terminal 30 Ignition Power
Terminal 87A TCC
Terminal 87 No Connection

Relay 2:
Terminal 85 Ign Power
Terminal 86 4th gear pressure switch
Terminal 30 Ignition Power
Terminal 87A No Connection
Terminal 87 TCC

If you are not using a computer controlled engine then you could probably skip the brake switch.