mikeb7

Chasing a no crank situation in a buddy's 82 automatic, and we narrowed down to lack of signal from ignition switch to the relay.
Assumed was ignition switch. and bought a new one,
Buddy installed it and no start/no change. But buddy also claims saw smoke from the switch.

Have since been going through rest of system cleaning contacts and grounds per the advice of other threads.

Lingering is the possibility that I now have two bad ignition switches, though (if that's even possible?)

How do I bench test the ignition switch? I'm bad at these 928 wiring diagrams, and can't make sense of the excess of pins on the back of that thing.

dr bob

Bench-testing the ignition switch with your DMM in the Ohms position:

Terminal numbers on the switch correspond to circuit and bus numbers in the cars.

There are three circuit 30 terminals on the switch. These three are common to each other. With the switch in any position, there should be zero resistance among any of those terminals.

There is one terminal P, that is common to terminal 30 when the switch is in position 0 only

There is one terminal R, that is common to terminal 30 when the switch is in positions 1 or 2 only

There are two circuit 15 terminals on the switch. These two are common to each other. These are common to terminal 30 when the switch is in position 2 or 3 only. (for engine-run loads)

There are two terminals X on the switch. These two are common to each other. These are common to terminal 30 when the switch is in position 1 or 2 only. (for high-current accessories, drops when starter is engaged)

There are one circuit 50 terminal on the switch. This is common to terminal 30 when the switch is in position 3 only. (cranks the starter)


In addition, there is an internal switch with terminals labeled 1 and 2, used to indicate when the key is actually in place in the ignition lock. These two terminals are connected when the key is inserted.



The ignition switch position zero is the key-insert position, no travel

Position 1 is the "accessory" position

Position 2 is the engine-run position

Position 3 is the starter-crank position


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I shared some starter circuit diagnostics a few months ago, intended to help folks diagnose starter cranking problems. Let me do some searching...

mikeb7

God bless, dr bob, that is exactly the kind of answer I sought. Printing it out for the shop. Thank you.

I searched and saved a number of threads on the subject, but never found a clear (to me at least) pin out of the switch.

Appreciate any threads you recommend on the subject.