[67stepside]

Hey kbs71,
The problem is that the terminal on the back of the ignition is a ground and not a power wire. The power is fed from the fuel guage feed [#3] on the cluster connectoin. So I assume that the hotter the temp gets the more ground is sent through the sensor. When you turn the key to start it will give the guage full ground and the guage will slam to hot, when it starts then the guage will slam back to cold. The wiring diagram link that you gave only shows idiot lights and not guages. I have a 67 service manual that has 40,50 and 60 series trucks in it and it shows that the temp sensor wire does not go through the ignition switch with guages, but no diagram for a 10 series with guages. I also noticed that the brake warning light is wired the exact same way as the temp and the brake light comes on when you start and then it goes back off. Any help will be greatly appreciated. Thanks