Ignition Switch Help

[Kroll]

Hi all,

I lurk more than I actually post. I figured I would have more relevant feedback and help from the "early cruiser group" regarding my ignition switch for my March 1972 FJ40.

Here's the scenario:
I parked my cruiser for the night after a 20 minute drive on the freeway. Then I came back to start it up so I could park it in the backyard. I was able to start the Cruiser with no issues, but the engine would die as soon the key turned to ON. I thought maybe a vacuum hose or my ignition idle wire broke (since I just finished repairing it the previous week). I found everything to be intact under the hood, so I decided to leave it for the night.

Today: I found time to tackle the issue. I disconnected the battery ground, before touching anything under the dash. Took a glance at my fuses and found them all to be in good order. I removed the retaining ring and pushed the ignition switch through the dash wall. I found the (fig. 1/2) the Black-Red wire to be discoloured and burnt at the plug.

When I removed the ignition switch I found the AM blade on the switch to be loose at the copper rivet (fig. 3/4).

My question is, what could have caused this in the first place? I can quite safely say that my wiring is all original, unmolested and in excellent repair for being 39 years old.

Then my next question stems from my purist approach to things. I was curious if I could retain my original key tumbler when replacing the ignition switch (part # 84450-60040). Has anyone here done this before? Any recommendations? There is one set screw on the side of the switch, (fig. 5) if I remove it, can I pull the tumbler out?

Thank you for your help!

FIG. 1

FIG. 2

FIG. 3

FIG. 4

FIG. 5

 

[67azcruizr]

yes, the tumbler will come out with the removal of that screw. I have not tried an earlier tumbler inside what's available now however

careful of the springs and pins

definitely replace that female plug too

 

[Kroll]

Do you reckon that the black rear piece threads out or that the front tumbler unit comes out?

I've tried both ways of disassembly with no results so far...might need to use some penetrant.

 

[Living in the Past]

When I bought my 68 back in 1974 the ignition had been replaced. The only key I got was the igntion which was a replament. Went to a locksmith and got a key to fit the driver's door and rear hatch. The old ignition switch was in the glove box. It's been a long time since 74 but I remember it was pretty easy to pull the tumbler out of the front and install it in the new switch so one key fit the whole vehicle.

 

[67azcruizr]

Do you reckon that the black rear piece threads out or that the front tumbler unit comes out?

I've tried both ways of disassembly with no results so far...might need to use some penetrant.

with the screw removed and the tumbler able to turn (with the key) inside the cylinder, it should come right out.

 

[67azcruizr]

I just pulled one apart just like the one you have there. it was a little stubborn. I used the key, turned to the ACC so that it's "locked in", as a means to pull out the cylinder.


the one on the very left is early (pre-'65), the middle one is just like yours only with the earlier screws in the back for wire connections('65-'69) and your style on right('70-'72).

i know, terrible pictures...........................

 

[Kroll]

Thanks for your input!
I got it out.


I will post a picture once I have a camera with me. This is good reference material for others.

 

[Cruiser_Nerd]

As far as the original problem goes............... the wire on the AM terminal is the power feed (12V in), I believe it is unfused (maybe a fusible link). IG is ignition, ACC is acccessory, and ST is starter. By your description it sounds like power wasn't making it through the switch to the IG terminal (the ignition is fed by the ST terminal until the key is released). Possibility that the switch failed and the AM terminal went to ground when you tried to start it. Did it smoke when you tried to start the truck?

Check for dead shorts and try a new switch. You can check continuity on the switch to see if it's any good.



This is from memory, I haven't played with anything this new in a while so don't take as gospel.

 

[foxfab]

Fire Investigator hat on.

The melting was caused by a high resistance connection between the two connectors typically caused by a poor/loose contact. Over time and lots of bumps the poor contact between the two connectors will build up resistance and overheat.