The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 700R4 Brake light switch?

1project2many · 02-14-2019, 02:05 PM

A simple solution might be to use a five terminal relay to operate TCC. Use the normally closed contacts for TCC power. Connect power from the brake switch to the relay coil. When the brakes are applied, the relay engages, and the contacts open breaking the circuit to TCC. With traditional terminal numbers you could connect as follows:

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

02-14-2019, 02:05 PM	#3
1project2many Registered User Join Date: Mar 2012 Location: Lakes Region NH Posts: 3,161	Re: 700R4 Brake light switch? A simple solution might be to use a five terminal relay to operate TCC. Use the normally closed contacts for TCC power. Connect power from the brake switch to the relay coil. When the brakes are applied, the relay engages, and the contacts open breaking the circuit to TCC. With traditional terminal numbers you could connect as follows: Terminal 85 Brake lights Terminal 86 Ground Terminal 30 Ignition Power Terminal 87A TCC Terminal 87 No Connection