Excess current in Ignition 1 circuit?

[70Duster440]

Kinda hoping 67Dart273 will chime in here.

Awhile back I replaced the ignition switch for no other reason than a maintenance upgrade to the electrical system. Cleaned up bulkhead connections while I was at it. Everything seemed fine and dandy except since then I notice an intermittent problem with the Ignition 1 circuit right at the column connector (DBL*). Car would start but then shut off as soon as the key hit the run position. Pull the connector apart, plug it back together, problem "fixed" for awhile. Then I noticed heat discoloration at that cavity of the connector and that it was getting hot to the touch.

My conclusion was a poor barrel connection. I pulled the two terminals out of the connector and plugged them together so I can better monitor them.

My question is, aside from possible resistance at the connector itself, is it possible there's a fault somewhere else causing excessive current flow through the circuit causing it to overheat? If so, where would the likely culprit be?

 

[RedFish]

Depending on year model, there may be items on that circuit causing the problem.
If there is an electric choke assist, its controller is highly suspect.
What you found under the column can be just evidence of a problem or problems somewhere else.

 

[Lonewolf3165]

Resistance is what will cause heat. Current(amperage) remains constant throughout the whole circuit. If you have a hot spot that's where the high resistance is. A good connection wont melt because of trouble in another connection. It will start to fry at the source of the highest resistance, whether it be a poor connection or a wire that is of too small a gauge.

 

[70Duster440]

Right, I understand that resistance causes heat. What I want to make sure of is that the hot connection isn't a symptom of a problem elsewhere - and it sounds like Lonewolf answered that for me.

Thanks to both of you for feedback.

 

[RedFish]

point to ponder... a circuit overload in you home will trip a breaker ( which is a result of heat ) rather than melt any one fixture.
I'm done. un subscribed, good luck

 

[67Dart273]

It IS possible that you have something amiss. One example might be a partially shorted alternator field winding, which does happen. (This will cause less than rated alternator full output.)

The most likely suspect, however, is the switch connector itself.

You have any added loads, upgraded ignition, etc?

And I assume you don't routinely leave the switch "in run" with the engine off?

Is there any evidence along the "run" circuit of damaged insulation or other heating?

 

[70Duster440]

Don't go away mad, Redfish. I was not discounting your reply by acknowledging Lonewolfs - despite how it might have sounded. That was not my intention.

The most likely suspect, however, is the switch connector itself.

This is what I would like to think since the problem surfaced after installing the new switch.

You have any added loads, upgraded ignition, etc?

Electric fan with relay but it's tapped at the starter relay. Have not changed the ignition (been running FBO for years).

And I assume you don't routinely leave the switch "in run" with the engine off?

I do not do this.

Is there any evidence along the "run" circuit of damaged insulation or other heating?

Not unless there's some recent damage I'm unaware of. Car is mostly for show with very little use. I'll have to do an inspection to rule it out but it's doubtful.

 

[70Duster440]

And I assume you don't routinely leave the switch "in run" with the engine off?

Like I said, I don't do this but it has been left on accidentally before. I assume the concern is overheat and damage to the ballast resistor.

 

[skykeith]

You need to use an ammeter to see how much current is actually flowing in the circuit and whether it is excessive or not. Without knowing how much current is flowing, you're just guessing whether it's poor connections or an excessive draw by a component.

 

[RedFish]

Lets recognize that some components under the hood are encased in ceramics and receiving some amount of cooling from the engine fan.
Yes resistance causes heat but where you can see the result is plastic under the dash.A blind man feeling for the problem might be focusing elsewhere.
Every electrical component was deemed at least minimally adequate when the car was new. This includes the white plastic connector in question. Over time, the amount of current drawn through that connector can only increase.
The wiper circuit may be very close to blowing its fuse, same with the blower motor circuit and others. All combined are not quite enough to burn open the fusible link.
Maybe there is/was a method to the madness in the fact that they made this one and the connector at rear of right valve cover from white plastics ( for sighted folks ).
Having said all that... Some will just beef up these connections as the fail until they reach the root of the problem.

 

[67Dart273]

..........Every electrical component was deemed at least minimally adequate when the car was new. This includes the white plastic connector in question. .................Maybe there is/was a method to the madness in the fact that they made this one and the connector at rear of right valve cover from white plastics .

I understand what you are trying to say, but the plastic HOUSING is not the cause of the heat. Regardless of the connector housing, the terminals inside are what are inadequate, as the infamous bulkhead connector has shown.

In retrospect, when I "was a kid" one of the best things I should have done was to stop by the state patrol garage and see "what they did" to electrically equip a patrol car!!!

 

[RedFish]

I understand what you are trying to say, but the plastic HOUSING is not the cause of the heat. Regardless of the connector housing, the terminals inside are what are inadequate, as the infamous bulkhead connector has shown.

In retrospect, when I "was a kid" one of the best things I should have done was to stop by the state patrol garage and see "what they did" to electrically equip a patrol car!!!

What I was trying to say is burned turns black. A black connector, wont beg for attention like the white does. Talk all day about inadequate connectors, rewire the car with 1/2 hardware and wires as big as the battery cables. All I know is these problems did not occur 40 years ago. Want to blame global warming ?
Cool LOL

 

[67Dart273]

. All I know is these problems did not occur 40 years ago. Want to blame global warming ?
Cool LOL

Actually they did occur, sometimes. I would not say "rampant" but did happen

Before "Al Gore invented the internet" I've spliced and run wires straight through the bulkhead, pickups seem to be more prone for the ammeter/ charging wires

I've replaced many TS switches which worked just fine -- except the brake lights didn't work

And a few other switches. Headlight, ignition, and heater, and often these could have been a connector failure as well as a switch failure --both showed heat damage. So which came first?

Lots of dimmer switches, but they are cheap, easy, and fast

 

[70Duster440]

Again, I appreciate everyone's input.

I've removed the terminals of that circuit from the connector to isolate them. Until I can dig deeper and test further I'm going to physically monitor that connection for heat. I imagine some heat would be normal but it was getting scary hot before. I've seen what heat/current damaged wiring looks like but overall the insulation looks okay.

I would also not be surprised if the terminals in the aftermarket ignition switch were not made to the same standards they were in 1970. If they're just a little bit looser....