Headlight switch going bad?

Mick

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There is a noticeable decrease in my idle when I pull out the headlight switch on my '66 Imp.
Thoughts?
 
Check that the load on the alternator isn't increasing enormously when you turn on the headlights - that might indicate issues with wiring through the bulkhead connector, regulator, headlight switch, dimmer switch etc. If it takes enough power away from the ignition system because it can't get all it needs due to high resistance in the headlight circuits, idle may suffer. It could also just indicate a bad regulator. My old Chebbie used to do that...

Check body grounds, (block to firewall), battery ground at block and at battery, postive post connections, etc etc. Be diligent and thorough.
 
Thanks, Ross. As preventive maintenance prior to noticing this issue, I replaced the original battery cables, cleaned bulkhead connectors, and all other connectors I could see under the hood, including starter relay and regulatory. Also cleaned dimmer switch. Leaning toward that headlight switch.
 
Soinds logical... I don't have the electrical expertise of others here so hopefully they'll chime in.

Just for shits and giggles throw another regulator on there and another coil.
 
There is a noticeable decrease in my idle when I pull out the headlight switch on my '66 Imp.
Thoughts?
Obviously, your alternator is not stepping up the output under load and that could relate to a battery issue, poor condition of the alternator or the voltage regulator. The regulator senses the system voltage and compares it to the battery voltage and increases accordingly. Your charging system is one of the simplest around but I don't have much confidence in the original voltage regulator. I'd go electronic which is about $34 but be sure if you go this route to have an excellent ground between the regulator and alternator shell. Electronic regulators can be wired easily for single or dual field alternators which brings me to the second issue, the alternator. Perhaps the brushes are so worn it can't maintain the correct output. Due to the simplicity of your charging system I highly recommend changing both the regulator and alternator especially when both come into question of performance. Be aware that there are a slew of rebuilt alternators out there that aren't worth a damn and fail prematurely. The price will indicate exactly what you purchase.
 
Obviously, your alternator is not stepping up the output under load and that could relate to a battery issue, poor condition of the alternator or the voltage regulator. The regulator senses the system voltage and compares it to the battery voltage and increases accordingly. Your charging system is one of the simplest around but I don't have much confidence in the original voltage regulator. I'd go electronic which is about $34 but be sure if you go this route to have an excellent ground between the regulator and alternator shell. Electronic regulators can be wired easily for single or dual field alternators which brings me to the second issue, the alternator. Perhaps the brushes are so worn it can't maintain the correct output. Due to the simplicity of your charging system I highly recommend changing both the regulator and alternator especially when both come into question of performance. Be aware that there are a slew of rebuilt alternators out there that aren't worth a damn and fail prematurely. The price will indicate exactly what you purchase.
Thank you. Should I upgrade on amperage as well and what is the advantage of dual field over single?
 
I'm sure you'll get a lot of different opinions on this . . . but, I was told that you really don't want to go over ~55 amps w/ the stock wiring, or you'll start frying components that weren't designed for that much current. Shouldn't need it either . . . original output (even in an Imp) was probably around 37.
 
Thank you. Should I upgrade on amperage as well and what is the advantage of dual field over single?
There is no advantage. One has an internal ground and is controlled on the positive side of the field by the regulator. The so called "dual" field (a misnomer because there aren't two fields.. just two connections) is controlled on the negative side of the field by the regulator and the positive side of the field is connected to the battery. Chrysler did this because it was cheaper and easier to do.

With the availability of electronic regulators for the internally grounded (single field connection) alternators, the advantage of the later regulator is gone.

So... changing to the later style isn't a bad idea at all, it's just not necessary.

Same with increasing the alternator capacity. Great idea if you need it. If you don't, it does nothing for you. Your car draws what it draws and that's it.

If you do increase the alternator capacity, it is a good idea to increase the wire size, but only because there now is the capability to draw more current. The way to do this is to run a wire directly from the alternator to the battery and bypass the original path through the firewall and ammeter. That's a good mod even if you don't change anything else.

There's a lot of misunderstanding on how this works... but you have to think of electrical draw. A larger capacity alternator isn't going to push more current through your accessories. Stuff like your lights are going to draw the current from the battery and the alternator is going to keep the battery charged. If you increase your draw, like let's say electric fans, a larger capacity alternator might be necessary to keep up with the demand.

But... Back to the OP.

There's nothing wrong.... The alternator and regulator are doing their jobs. It's charging the battery and making up for the draw of the headlights. Do the math.... If you light up 4 headlight bulbs and let's say they are 50 watts each and at 12 volts, that's over 16.6 amps you are drawing. The draw to the battery becomes more and the regulator turns the field on to start making the alternator work a little harder.

So.. the alternator starts working a little harder and the power to drive it has to come from somewhere.... Hence the dip in RPM. More likely, the idle just needs to come up a touch or the car needs to be tuned up.

As Ross says, any added resistance in the circuit will increase the draw, but if everything is "up to snuff", that's probably not a problem.
 
Thank you. Should I upgrade on amperage as well and what is the advantage of dual field over single?
Personally I would not recommend any huge output updates to the alternator unless you are prepared to update the wiring harness under the hood and dash
Increasing amps can fry the harness really quickly especially if there are any ground and connections issues
The wiring will be aging...
So be careful
Don't go too high in output
If you currently have a 35amp consider a 40-45amp max
If you really want lots of power then be ready for harness mods or replacement
This refers to the charging circuit guys...
 
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Thanks for that very detailed explanation-covers lots of ground and I appreciate you taking the time.
There is no advantage. One has an internal ground and is controlled on the positive side of the field by the regulator. The so called "dual" field (a misnomer because there aren't two fields.. just two connections) is controlled on the negative side of the field by the regulator and the positive side of the field is connected to the battery. Chrysler did this because it was cheaper and easier to do.

With the availability of electronic regulators for the internally grounded (single field connection) alternators, the advantage of the later regulator is gone.

So... changing to the later style isn't a bad idea at all, it's just not necessary.

Same with increasing the alternator capacity. Great idea if you need it. If you don't, it does nothing for you. Your car draws what it draws and that's it.

If you do increase the alternator capacity, it is a good idea to increase the wire size, but only because there now is the capability to draw more current. The way to do this is to run a wire directly from the alternator to the battery and bypass the original path through the firewall and ammeter. That's a good mod even if you don't change anything else.

There's a lot of misunderstanding on how this works... but you have to think of electrical draw. A larger capacity alternator isn't going to push more current through your accessories. Stuff like your lights are going to draw the current from the battery and the alternator is going to keep the battery charged. If you increase your draw, like let's say electric fans, a larger capacity alternator might be necessary to keep up with the demand.

But... Back to the OP.

There's nothing wrong.... The alternator and regulator are doing their jobs. It's charging the battery and making up for the draw of the headlights. Do the math.... If you light up 4 headlight bulbs and let's say they are 50 watts each and at 12 volts, that's over 16.6 amps you are drawing. The draw to the battery becomes more and the regulator turns the field on to start making the alternator work a little harder.

So.. the alternator starts working a little harder and the power to drive it has to come from somewhere.... Hence the dip in RPM. More likely, the idle just needs to come up a touch or the car needs to be tuned up.

As Ross says, any added resistance in the circuit will increase the draw, but if everything is "up to snuff", that's probably not a problem.
 
Thank you for the sound advice.

Personally I would not recommend any hugh output updates to the alternator unless you are prepared to update the wiring harness under the hood and dash
Increasing amps can fry the harness really quickly especially if there are any ground and connections issues
The wiring will be aging...
So be careful
Don't go too high in output
If you currently have a 35amp consider a 40-45amp max
If you really want lots of power then be ready for harness mods or replacement
 
Increasing amps can fry the harness really quickly especially if there are any ground and connections issues

Not really... Only if there is a larger current draw. For example, let's say you put a large amplifier and wired into the existing harness. Then your current passing through the harness would increase... but if you aren't increasing the draw, then you aren't changing anything.

Here's an example... You have a 50 watt bulb and 12 volts. You have about 4.2 amp draw. Connect it to a battery with a 100 amp capacity. You still have a 4.2 amp draw. Connect it to a battery with 1000 amps and you still have a 4.2 amp draw. It's the same with the alternator. It doesn't push any more current through the system... The system just draws what it needs. It does charge the battery faster and you should increase the size of the wires charging the battery.
 
OK, thank you everyone for the sage advice. Collectively you guys have already saved me a lot of time and money-from selecting my ride to today.
I think the problem is in the headlight switch. Reliably after 15 minutes or so the low beams would start kicking off and on-regardless of accessories on/off. I caught a whiff of something hot, and as I had already dropped the driver side a/c vent, stuck my hand up behind the dash to feel for heat. The flesh still hanging from the back of the headlight switch tells me it is, indeed, HOT.
 
OK, thank you everyone for the sage advice. Collectively you guys have already saved me a lot of time and money-from selecting my ride to today.
I think the problem is in the headlight switch. Reliably after 15 minutes or so the low beams would start kicking off and on-regardless of accessories on/off. I caught a whiff of something hot, and as I had already dropped the driver side a/c vent, stuck my hand up behind the dash to feel for heat. The flesh still hanging from the back of the headlight switch tells me it is, indeed, HOT.
That does sound like a switch problem alright.
 
Not really... Only if there is a larger current draw. For example, let's say you put a large amplifier and wired into the existing harness. Then your current passing through the harness would increase... but if you aren't increasing the draw, then you aren't changing anything.

Here's an example... You have a 50 watt bulb and 12 volts. You have about 4.2 amp draw. Connect it to a battery with a 100 amp capacity. You still have a 4.2 amp draw. Connect it to a battery with 1000 amps and you still have a 4.2 amp draw. It's the same with the alternator. It doesn't push any more current through the system... The system just draws what it needs. It does charge the battery faster and you should increase the size of the wires charging the battery.
I am referring to the charging circuit wiring
Sorry I should have been clearer on that ...
 
There is no advantage. One has an internal ground and is controlled on the positive side of the field by the regulator. The so called "dual" field (a misnomer because there aren't two fields.. just two connections) is controlled on the negative side of the field by the regulator and the positive side of the field is connected to the battery. Chrysler did this because it was cheaper and easier to do.

With the availability of electronic regulators for the internally grounded (single field connection) alternators, the advantage of the later regulator is gone.

So... changing to the later style isn't a bad idea at all, it's just not necessary.

Same with increasing the alternator capacity. Great idea if you need it. If you don't, it does nothing for you. Your car draws what it draws and that's it.

If you do increase the alternator capacity, it is a good idea to increase the wire size, but only because there now is the capability to draw more current. The way to do this is to run a wire directly from the alternator to the battery and bypass the original path through the firewall and ammeter. That's a good mod even if you don't change anything else.

There's a lot of misunderstanding on how this works... but you have to think of electrical draw. A larger capacity alternator isn't going to push more current through your accessories. Stuff like your lights are going to draw the current from the battery and the alternator is going to keep the battery charged. If you increase your draw, like let's say electric fans, a larger capacity alternator might be necessary to keep up with the demand.

But... Back to the OP.

There's nothing wrong.... The alternator and regulator are doing their jobs. It's charging the battery and making up for the draw of the headlights. Do the math.... If you light up 4 headlight bulbs and let's say they are 50 watts each and at 12 volts, that's over 16.6 amps you are drawing. The draw to the battery becomes more and the regulator turns the field on to start making the alternator work a little harder.

So.. the alternator starts working a little harder and the power to drive it has to come from somewhere.... Hence the dip in RPM. More likely, the idle just needs to come up a touch or the car needs to be tuned up.

As Ross says, any added resistance in the circuit will increase the draw, but if everything is "up to snuff", that's probably not a problem.
This is next to a pile of crap written by someone who knows little to nothing about ohm's law or the workings of an automobile charging system.
 
moving on... here is my head light switch when I pulled things apart a few years ago..
it was melted something nasty... I luckily had bought another headlight switch that included the plug.
20140228_200954.jpg
20140228_200946.jpg
 
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