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77 f100 2wd, manual, 302 short bed
The PO ran a new wire from the ignition switch to the s terminal on the solenoid. This works. However, the old red with light blue stripe wire that was left in place has voltage on both ends when the key is on. It is not connected at either end but runs through a plug under the dash. Any ideas?
There is also a light purple wire with a white stripe that is taped to the bright blue wire coming off the ignition switch. Any ideas what that light purple wire goes to? Any idea what the bright blue wire should be connected to?
Since there is voltage there with just the key in RUN, there's a better than average chance that the PO bypassed a shorted out Red w/blue wire because every time he turned the key on the engine tried to start.
Better to have repaired the fault of course, but it still got "fixed" to a working state.
Since it's disconnected at both ends, then it's got a short circuit somewhere in-between. Probably felt it would be a real bear to track down.
The Dual Brake Warning Lamp wire niko mentioned would normally be attached to a lug on the outside of the ignition switch. In the old days this connector was the "proof out" of a switch. Simply goes to ground when the key is turned to START. In our case that's so that the light on the dash will momentarily illuminate when the vehicle is in START only.
Basically a bulb test, like all modern cars do electronically now. Ours just did it the old fashioned way.
Maybe it's disconnected because of another fault causing the light to be on all the time?
Thanks for the advice. It does work as is, but I don’t like those live ends just hanging there. I’ve called them for now.
For it the purple and white wire, I had to put on a new proportioning valve and a single wire warning light switch. The instructions just say to connect both wires to the single wire. How would that work?
It works just fine as it turns out. We've been doing it that way for several years now and they've all functioned as expected.
The old 2-wire switches simply attached both wires together inside the switch body, where the newer 1-wire switches need the two wires brought together outside of the switch. If that makes sense.
But the function is the same either way. When the switch is tripped, it's simply grounding the contact to the prop valve's body. The ignition switch in START is just a "bypass ground" for lack of a better term.
But after many years and many hundreds and thousands of installs, they seem to function as expected.
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