I need some electrical help
 

Today I was trying to get my dads heater switch working on his 70' (it has never worked on it's own). It has a toggle switch rigged up to the "ignition unfused" on the fuse panel. I tried 3 different heater controls and none work. :banghead: . When I hook up my test light, at the heater fuse it lights up, but when I test all 4 terminals on the plug it won't light up. Where should I look for the problem?. Thanks

There should be one key-on wire at the switch plug, I think it is brown in color. If you have no power at the switch plug, and the fuse is good, then there is a break in the wire between the fuseblock and the switch plug. You need to dig into the harness with a test light/DVM and test every so often until you find the break. Or, it could be right at the fuseblock connector. Gotta have power to the switch first before anything elso can be looked at.

The other three (blue, yellow, and orange) go to the resistor. Orange is "HIGH", which is basically direct to the motor. The other two are low and medium. That is, if this truck has no A/C.

Mine is rigged the same way and the blower motor seems to be bad, have you checked that yet? I have been told that they get flat spots in the brushes and may stick in that spot. GL. Let us know what you find.

glock35ipsc, you are correct about the brown 14 gauge wire. I'm not getting juice to the end of it. The fuse is lighting up so it must have a break between the fuse and the plug. Hotrodtroy, I think the blower motor is fine because the toggle switch that is rigged up works the heater fine. Thanks guys.