Easiest way to determine if it's the cam actuator, rod, switch, or key lock is too...
Reach underneath the dash, on the top of the steering column. Twards the steering
wheel from where the aluminum bracket bolts up the steering column. Turn the key while feeling the rod. If the rod moves, it's the ignition switch. If not, then it's the actuator cam. To make sure, turn the key to "run" position. Now insert a piece of wire or something about an 1/8th inch into a hole directly under the key switch. Aproximately at the 7 O'clock position if your looking directly at the column from the side. Pull out the key, lock and all Make sure the "tab" isn't broken or worn to the point it's not engaging it's mating hole in the column.
I just happen to be going through this now. If you want, I'll take some pics.
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Dave
'93 Ranger XLT 4.0, 4x4, 179,000 and counting. (For Sale)
'92 F-150 XL I6, M5OD, 4x4, 186,000 and counting. (For Sale)
'90 F-250 XLT 7.3 IDI, E4OD, 181,000 and counting.
'95 Explorer XLT 4L, 4R55E, 4x4. 156,000

Hiding in my own little
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