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GM Power Relay System
Created by TRNi member, Dan Tucker

Componant Description






      The Power Relay System was designed to eliminate DTC 66, 67, 81, 82, and 83 on 1995-up GM trucks. These codes are many times set because the ignition switch fails to supply enough voltage to the Transmissions ignition circuit, just after start up. Once the ignition switch fails to provide adequate voltage to the solenoids, the feedback to the computer trips any combination or all of the codes above. You can replace the ignition switch, as a possible temporary fix, or install the Power Relay System and FIX the problem.

The GM Power Relay System was designed by TRNi member, Dan Tucker The advantages of installing the Power Relay System are:
  1. It will make the ignition system more reliable.
  2. It is much faster than replacing the ignition switch.
  3. It is far less expensive than replacing the ignition switch.
  4. Any transmission shop could easily install the Power Relay System, where as the ignition switch replacement, usually falls in the general repair field.

      Installing the relay is very simple. All the wires are clearly tagged. The relay installs under the hood at the fuse-relay box on the drivers side. All you do is connect the GROUND to the master cylinder. Then connect a 12 VOLT supply, that is easily found behind the fuse-relay box. Next you tap into the main IGNITION circuit inside the fuse-relay box. This fuse is easy to find, as it is the front most outside ignition fuse. The last wire you splice into the transmissions case connector's "E" terminal. Mount the relay and you are finished. It takes about 20 minutes to install.

Click here to view an installation schematic Click here to view an installation schematic


      The Power Relay System draws VERY low amps. Because the Power Relay System is being 'excited' from a different ignition circuit, it will always power up with the key on. The different ignition circuit will never 'feel' the draw of the added relay. The system provides a 10 amp fuse in the 12 volt power source as soon as it leaves the junction behind the fuse box.

      The Power Relay System will also work on the 4T60E's that blow the #5 transmission fuse. We have found that many times GM has so many other circuits sharing the transmission fuse, it is simpler to add the Power Relay System and provide a consistent 12 volts to the transmission-transaxle to keep the powertrain shifting. There are many other uses for the Power Relay System.