Ignition switch diagnosing and trouble shooting?

[LanceH]

Hi Fellas,

I have a 1972 Challenger Rally 340, 4-speed

Do you have any suggestions to help me trouble shoot what I think is a failed (or failing) ignition switch?

A few days ago, it started and ran fine. Now, I run the key to 'start', and nothing. I have had similar problems in the past, but not recently. I replaced the starter relay last year, and that seemed to fix any issues I had been having.

What I've done so far.
- Battery, good and fully charged
- I can 'jump' start it by touching the terminal on the starter relay on the inner fender
- Engine compartment, no bad fuse-able links that I can see
- Interior, all fuse block fuses are good, and again no bad fuse-able links that I can see
- In the engine compartment, I put a test light on the yellow ignition wire at the starter relay. When the wife turns the key to 'start', the test light does NOT come on - I was expecting the test light to light up.
- Manual transmission clutch start switch. There is a green wire at the starter relay, and I trace it inside the car to the clutch pedal. Connected or disconnected - it doesn't seem to make a difference.

Any other suggestions, or do I just need to get ready to tear down the steering column?

Thanks in advance
Lance

[Bullitt-]

There's a wide flat connector along the steering column that you will find the yellow wire where it comes from the ignition switch. Test there to see if you get power with the key turned to start, if not it's probably the switch. If you get power there is a bad connection somewhere, probably at the bulkhead connector on the firewall.

[Cuda Cody]

 

If it is in the column, it's not a very hard fix.  It comes apart pretty easy and there's some videos on here on how to do it.

And Welcome to the forum @LanceH     Post some photos of your car when you have time.   

[Chryco Psycho]

The yellow wire goes through 2 plugs one at the base of the column & one at the bulkhead test& clean both of those places first 

[JS29]

  @LanceH 

[Chryco Psycho]

Welcome to the site from Panama 

[LanceH]

Thanks everyone for the quick help and great suggestions. I'll post an update soon!
Lance

[LanceH]

Update for 28-April

Good news:
- With your suggestions, I confirmed that the ignition switch seems to be working.
- I also tested the continuity of the steering column wiring harness to the ignition switch, and all of the switch positions
---- I got help from the following YouTube video = https://youtu.be/UXglJs2107c, title = Mopar Ignition switch test

Observations
- At the large flat connector of the "steering column wiring harness" to the "bulkhead harness", the red power wire had gotten hot, the terminals are a little crispy, and the plastic is brown/discolored at the red wire location. All the other connections and terminals look okay.

Next steps
- I'll trace the "red - power" and "yellow - ignition" wires to the bulkhead disconnect, and see if there's any problems

Questions
? Would it be okay to make wiring changes and to "bypass" the bulkhead disconnect? I'm thinking about re-splicing both the "red - power" and "yellow - ignition" wires so they don't have to run though the bulkhead connectors.

? Should I also add a Fusible Link to the "red - power" wire? If so, what size? Would 60 Amp be okay?

Thanks!
Lance

[Chryco Psycho]

I would make sure the column flat plug is clean & tight.
you can bypass the bulkhead or just got through it but you may still want a connection there if you have to disconnect .
The Yellow wire is very low current , the red wire is high load & protected by the fusable link form the start relay so no need to add a second one

[LanceH]

Success! It starts again.

Problem was at the wide flat connector along the steering column, specifically the red power wire. It had gotten hot, the terminals were crispy, and the plastic on that terminal were brown/discolored at the red wire location. Too much resistance.

Thanks to @Chryco Psycho and @Bullitt- !!

Lance