Smoked some wires today

[Mattax]

20 Ohms was from the ground terminal to the ring terminal under the bolt.

The little red wire was on there when I got it.

Either the probes didn't get a good contact or the red grounding wire has a lot of resistance in it.

No neutral safety switch connection I can see but I'm not surprised.

The green wire from the clutch was broken and frayed when I got the car so I grounded that cable out on the firewall.

It's an either or. You car with the standard transmission has a switch on the clutch or the shifter.
This is from '71 FSM. '72 might still be this style diagram?

S4 18 ga Dark Green is for cars with Manual transmission.
S4 18 Br/Y* is for cars with an automatic transmission.

The clutch start switch is the ground. When the clutch is depressed, the switch is closed and electricity can flow to ground.

Key was not on or in the car when i did the tests.

Well then the battery terminal shouldn't be connected to anything, right?
You could recheck it, but that seems to be a problem.
Take off the wires and recheck. If it passes then, the short is in the wiring not the relay.
If it is no good, feel free to open it up so you can see how it works and maybe even what's wrong.
A new one or a good used one should be easy to obtain.

 

[72Ruster]

Ok so rechecked. There's definitely only a few ohms resistance between B and S, infinite between B and G. Infinite between B and I. 25ohms from S to I. I think I tested the first time by touching the connector on G and not the post.

 

[72Ruster]

Either the probes didn't get a good contact or the red grounding wire has a lot of resistance in it.



It's an either or. You car with the standard transmission has a switch on the clutch or the shifter.
This is from '71 FSM. '72 might still be this style diagram?
View attachment 1715580944
S4 18 ga Dark Green is for cars with Manual transmission.
S4 18 Br/Y* is for cars with an automatic transmission.

The clutch start switch is the ground. When the clutch is depressed, the switch is closed and electricity can flow to ground.


Well then the battery terminal shouldn't be connected to anything, right?
You could recheck it, but that seems to be a problem.
Take off the wires and recheck. If it passes then, the short is in the wiring not the relay.
If it is no good, feel free to open it up so you can see how it works and maybe even what's wrong.
A new one or a good used one should be easy to obtain.

Yeah the ground was just really dirty. Cleaned it up and it shows less than 1ohm. Ill take the wires off and check them.

 

[Mattax]

Maybe the relay contacts are stuck, but regardless of cause, the connection from B to S is no good.
I don't think S to I should have connection either. I'd call it bad. Oh I see that's with the wires on. Yea check to be sure with the wires off.

 

[RustyRatRod]

If you smoked wires, did you at least get a buzz?

 

[Mattax]

Ok so rechecked. There's definitely only a few ohms resistance between B and S, infinite between B and G. Infinite between B and I. 25ohms from S to I. I think I tested the first time by touching the connector on G and not the post.

Does this schematic of the inside of help you picture what connects inside starter relay?

Ignition to ground should have resistance.
Nothing else connects.

 

[72Ruster]

Short is in the wiring. No continuity across the solenoid with the wires off. Testing the wires there is a short between A1B (red wire that goes to firewall connector) and S5(black/brown wire from starter). No continuity between either wire and H2 (ignition2) wire.

 

[Mattax]

A1B goes to the fusible link and then inside to the main splice etc..
S5 (12 ga brown) goes to the starter solenoid.
The only place they could be touching is in the engine compartment where they run next to each other along the fender.
But what happened, happened with the key was in Start. So this doesn't make sense - at least not yet to me.

 

[72Ruster]

A1B goes to the fusible link and then inside to the main splice etc..
S5 (12 ga brown) goes to the starter solenoid.
The only place they could be touching is in the engine compartment where they run next to each other along the fender.
But what happened, happened with the key was in Start. So this doesn't make sense - at least not yet to me.

Yeah they don't even come close to each other in the engine bay. The connector for the A1B is super hashed though. Pretty melted and I can tell its been spliced in. Don't even see the fusible link. Just looks like wire. Fire is getting pretty close so Ill have to check it out later.

 

[67Dart273]

You guys can theorize all you want but there is only one way to find these shorts, and that is to unwrap the harness and look for them. "Back in the day" a dealer mechanic would have replaced them.

OP you are right about one thing, the ignition switch. the contact pieces can get loose and 'waltz around' in the switch, causing interesting problems

If that part of the problem is stable, IE not too intermittent, that specifically can be quickly checked with an ohmeter / continuity checker, with the switch disconnected

 

[72Ruster]

You guys can theorize all you want but there is only one way to find these shorts, and that is to unwrap the harness and look for them. "Back in the day" a dealer mechanic would have replaced them.

OP you are right about one thing, the ignition switch. the contact pieces can get loose and 'waltz around' in the switch, causing interesting problems

If that part of the problem is stable, IE not too intermittent, that specifically can be quickly checked with an ohmeter / continuity checker, with the switch disconnected

I don't mind checking everything that was suggested. Theres more than a single problem with the wiring in the car, but I do think this issue is the ignition switch. It's very consistent about starting a fire so should be easy to check once my steering wheel puller gets here. Good bit of fried wires that I've found so far.

 

[72Ruster]

Ok so update time! Finally got the parts in and smoke cleared enough to work on the car. Ignition switch is completely toast. Came apart as soon as i took it out of the column. Turn signal switch had some broken pieces on it so Im glad I got the replacement for that too.

On the new ignition switch there is a small black wire that wasn't on my old switch. Anyone know what its supposed to go to?

What's the tiny switch with the two red wires do? They were kind of chewed up at the connector side

Pics below

 

[72Ruster]

You guys can theorize all you want but there is only one way to find these shorts, and that is to unwrap the harness and look for them. "Back in the day" a dealer mechanic would have replaced them.

OP you are right about one thing, the ignition switch. the contact pieces can get loose and 'waltz around' in the switch, causing interesting problems

If that part of the problem is stable, IE not too intermittent, that specifically can be quickly checked with an ohmeter / continuity checker, with the switch disconnected

 

[72Ruster]

Couldnt really test for shorts in the switch since it fell apart but Im assuming that it would not be working properly in this condition. lol



View attachment 1715584721

 

[72Ruster]

Ah found some of what I was looking for. Two red wires are for the key in buzzer which doesn't work and the small black wire would go to the gear shift lever. Manual has that listed as an orange wire. Car is a stick so don't have that either. lol

 

[72Ruster]

A1B goes to the fusible link and then inside to the main splice etc..
S5 (12 ga brown) goes to the starter solenoid.
The only place they could be touching is in the engine compartment where they run next to each other along the fender.
But what happened, happened with the key was in Start. So this doesn't make sense - at least not yet to me.

See above posts

Do you have any tips on looking through the rest of the wiring on the dash side? I checked continuity across several points at the connector on the dash side and got beeps. I'm not sure if they're supposed to be electrically touching. Is it just getting under there with the chassis guide and figure out what shouldn't be touching? Thanks in advance