Ignition switch question

[peng155]

Hey Guy's,

A quick general question about the ignition switch diagram in the FSM....

I need to find a wire that has power on it when the ignition switch is in the start/on position... For the following diagram

Would I be correct that I could tap into the wire coming off of position 14, or 16 provided that they had +12vdc going to them from somewhere?

Thanks

[Zed Head]

That seems to be the case. I've recently read, on a thread on the forum somewhere, that some of contacts of the early ignition switches lose power for a moment when switching from Start to On. Something to be aware of.

[jfa.series1]

Don't overlook the radio power as a switched power source.

[peng155]

Great, thanks for the info... Just wanted to make sure I was interpreting the drawing correctly

[Captain Obvious]

Hold on. You don't have it right yet... The wire going to what you have identified as position #14 is the SOURCE for all the other functions and it's hot at all times. Of course "hot at ALL times" include both "ON" and "START", but that's not what you're looking for.

The only choice you have for a wire that is hot in both ON and START (and only in ON and START) is the one going to position 16. According to the wiring diagrams, you're after the black/white wire, and it was used on earlier years for ballast defeat when starting and on later years for that as well as powering the ignition module, etc.

All that said though, according to the wiring diagrams, there was a change in the ignition switches between 72 and 73... The 72 version I have shows NO such connection available at the switch like they do in all the later years. In 72 (and presumably earlier?) The black/white wire is only hot in START, and not in ON.

So... This might depend on what year you're working on? If you're working on what's in your sig, then you might not have any option.

[peng155]

Hold on. You don't have it right yet... The wire going to what you have identified as position #14 is the SOURCE for all the other functions and it's hot at all times. Of course "hot at ALL times" include both "ON" and "START", but that's not what you're looking for.

The only choice you have for a wire that is hot in both ON and START (and only in ON and START) is the one going to position 16. According to the wiring diagrams, you're after the black/white wire, and it was used on earlier years for ballast defeat when starting and on later years for that as well as powering the ignition module, etc.

Thanks for clarifying that Capt. I am working on a 71, but at the time I posted my question I couldn't readily find the correct picture... so I just pulled one that showed something similar, but not exactly what a 71 is.... Thanks for the info, and sorry for the confusion... But you and the other guy's did provided me the answer I was looking for, which was how to read these switch diagrams ....

Many Thanks.....

Edited September 6, 2014 by peng155

[Captain Obvious]

Glad to help. I just took a look at the FSM years I have (downloaded from xenons30) and according to the service manuals, those switches were all over the map! Earliest I have is 72 (and I don't have 75), but pretty much everything else was different every year! 77 and 78 looked the same, but that doesn't do you any good.

71 might be the same as 72, but after seeing all the other changes over the years, I'm not really confident. Here's the earliest I have. Its from a 72. Note that the diagram is turned 90 degrees from the way they depicted later years and I find it harder to read. But once you figure that out, it's not too bad. I made a couple notes to try to help:

But you'll notice that there is NO connection that is hot in both ON and START. There are a couple choices for ON and there area couple for START, but nothing that covers both. They are mutually exclusive other than the hot at all times source wire.

So you either need a 71 manual or forget the manual completely and just measure the connections on the back of the switch. I'm not sure what you want is available that year.

Is there a specific reason you want hot in START? Not intending to pass judgment, but it seems a little odd. :bulb:

[peng155]

Is there a specific reason you want hot in START? Not intending to pass judgment, but it seems a little odd. :bulb:

I'm wiring in a new alarm system.... and I needed to find a place to tap the alarms Ignition connection into.... I thought I needed to find a source that was hot while in the Start & Run position due to what Zed Head posted...

I've recently read, on a thread on the forum somewhere, that some of contacts of the early ignition switches lose power for a moment when switching from Start to On. Something to be aware of.

But now after re-reading the install manual I think I'll be ok in just tapping into any location that's hot, so I'll try jfa.series1 suggestion of using the radio circuit.

[Captain Obvious]

Gotcha. Good luck with the project!

[peng155]

Gotcha. Good luck with the project!

Thanks.. I appreciate your help