Case 1390 ignition switch

My ignition switch has a short in it, or there is a short behind it because my engine would not start and smoke started coming out from under the dash. Whats the easiest way to get the ignition switch out? The wires behind it are so short that they cannot be drawn out to any lengths from underneath. Do I have to take the whole dash off?

Assuming you've disconnected the battery, can you drop the whole switch assembly down by unscrewing the locking nut on the outside of the switch?

Yes, I disconnected the battery and brought the ignition out from under the dash. But in order to put the new ignition in and to find the short, if it is not in the ignition switch, I need to have those wires exposed. The ignition wires are so short that I cannot draw them out from under the dash enough to have a look at them, or to re-attaching them. I cannot see which wire goes where. Nor can I follow the wires to locate the short. The bolts that hold the dash on are situated such that getting them off is almost impossible. The fuel tank is in the way. Without cutting away enough of the area around the switch hole so I can get into the area I need to take the dash off. Obviously I prefer to not damage the dash. I have the workshop manual.
Thanks for getting back to me.

Not too bright of light, small mirror, and a test probe light jumped off the battery is what I would use. Your looking for the wire off the ignition switch which is grounded.

Not sure if you can use these "tips" but I used a tail light bulb or even a dash light bulb to illuminate areas up under a truck dash. A couple of alligator clips and some pieces of small, flexible wire. I've soldered wires directly to 1156 or 194 bulbs. The 1156 gets pretty hot, so watch where you lay it, or you'll melt other wires or nylon air brake tubing.

And when checking for a dead short (smoke!), supply the suspected circuit in series thru an old seal beam headlight. These headlights will pass about 5 amps, which will not damage a wire bigger than about 20-22 gauge. I have used a headlight in place of a blown fuse to help find a short circuit.
If the headlight burns nice and bright, the short is active, but the wires won't smoke.
Then go downstream, wiggling or unhooking things until the light goes dimmer, or out. However, if the load you are trying to run exceeds 10-15-20 amps, the bulb may glow somewhat, because power is flowing thru the headlight filament and subsequently, thru your normal load.
This strategy keeps you from blowing endless fuses or further damaging your wires while you search, and if you shine the sealed beam on a wall or ceiling, gives you a visual clue when you discover or get close to discovering the short.

As said above, I have used a headlight (temporarily) in place of a blown fuse. If the headlight glows brightly, dont put a new fuse in until you get the headlight to glow some shade of orange.

This post was edited by LPakiz on 06/13/2022 at 06:31 am.

Mark, in your case, I might unhook the positive battery cable and jumper a seal beam headlight from the battery post, thru the seal beam and onto the cable.
With everything off, there should be no glow, or very little. (Even the dome light or computer controlled ignition will flow some small amperage thru the seal beam)
If you have a pretty bright light when there shouldn't be much current being used, the short is active, but at least you won't damage your wires,switches, relays, fuses, etc. while you look.

You might try removing fuses, one at a time, until the light goes dimmer or out. When a removed fuse alters the headlight brightness, look up in the book what that fuse supplies. Then head to that component or circuit and unhook things, one at a time. Re-hook each component before proceeding to the next one.