Please help - Keep blowing ALL bulbs, something is screwy with the charging system

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barsteel

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Hello!

A while back, I posted about having difficult time getting the headlights to work. I kept on blowing the lamps, and it seemed to be cured by re-using the old dimmer switch.

Fast forward to yesterday. I was poking around under the dash trying to get the dash lights to work. I checked that I had power at one of the terminals of the dash dimmer. To check if the switch was bad, I jumped from the hot terminal to the two others. One did nothing, the other immediately blew a fuse. I replaced the fuse and reconnected the plug.

I have no idea if what I did under the dash really screwed something up, but I started having the same issue I had before.

I started the engine, turned on the lights, reved it, and the one operating headlight got incredibly bright and blew. I also blew all the tail lights. I've already replaced the voltage regulator, and the alternator is brand new. The new voltage regulator had no affect at all. I have a volt meter in the car, and it reads just below 12 when I'm blowing lights.

I put a voltage meter on the headlight socket. I was getting around 15.5 volts at idle, but when I reved the engine, the volts jumped to 40+!

Oddly, it stopped happening as quickly as it started. I put in another bulb, and it didn't blow. I rechecked the voltage, and it only went to 16. The headlights didn't blow.

When the car stopped overcharging, it seemed as if the ammeter started working, and the voltage meter read around 14.5 volts.

I've had problems with corrosion in the bulkhead connectors, and I've scraped them as clean as I can get them. Could a bad connection at the bulkhead cause an overcharge condition?

I'm pulling my hair out with this one...

Thanks...

Chris
 
The only thing I can think of is the voltage regulator and while you have said that you have replaced it, it doesn't sound like it is doing its job properly.
 
Wollfen -

I thought about it some more, and it appears as if the voltage regulator is working intermittently.

When the lights blow, the volt meter (NOT the ammeter) show a slight discharge. The ammeter does not appear to move.

When the lights don't blow, the volt meter reads around 14.5 volts, which is about what it should be. The ammeter in the dash appears to work as well.

One question - when I bought the new voltage regulator, the guy at Napa told me that there were 2 options. 1 for 34 or 48 amps (not the exact numbers, but they were close), and one for 60 amps. I cannot ID the amperage of alternator the PO installed, but matched up the voltage regulator with the one that was in the car.

If the PO installed a 60amp alternator, and I had a mis matched voltage regulator, could that cause the voltage regulator to work intermittently?

Chris
 
Chris,
Humor me. About 20 years ago I was driving down the interstate at dusk in rush hour when a guy pulled up behind me and turn off his headlights, I was driving a 68 NYer. I had known that I lost my dash lights, radio and cb. The car was running and I was an hour from where I needed to be. What I didn't know was that everything that was on was blown; headlights, tail lights, marker lights, turn signals, brake lights... You get the picture everything. There wasn't a single fuse blown - none! Finally it chunged and died.

From what you said the only time that you blew a fuse was when you were testing the switch. Is this correct?

My problem was that the wires on the back of the alternated had shorted together and was sending the full output of the alternator to everything instead of sending it through the voltage regulator. When this happened all of the bulbs that were on blew, acting like a fuse because the current flow was going in reverse. Essential the bulbs protected the fuses.

I hope this helps. I know that electrical issues can be a nightmare.:BangHead:
 
live4theking said:
Chris,

My problem was that the wires on the back of the alternated had shorted together and was sending the full output of the alternator to everything instead of sending it through the voltage regulator. When this happened all of the bulbs that were on blew, acting like a fuse because the current flow was going in reverse. Essential the bulbs protected the fuses.

I hope this helps. I know that electrical issues can be a nightmare.:BangHead:
Click to expand...

A couple of things you may want to check:

1. Make sure that the voltage regulator is tight on the firewall. If it's loose, you'll have intermittent ground.

2. Check all of the wires in the engine harness individually. If it's the original harness, it may be compromised from years of temperature cycling.

If you don't already have one, invest in a color wiring diagram from ClassicCarWiring.com. They are invaluable for electrical work.

And a word of advice:

When it comes to electrical issues, learn what is right and fix what is wrong.

Guessing can turn your car into a charred pile of scrap metal.

Hope the input helps.

John
 
Good words of advice. An intermittent connection can and will do the same thing as a flaky regulator, though it sounds like you're saying this condition exists as soon as you turn the car back on?

Your dimmer switch test shouldn't have caused this. Basically the switch has power coming to it and switches that power between the two circuits for high or low. Now, it you inadvertently grounded it by mistake while testing (bumped an alligator clip against bare metal, for example), all bets are off.

OTOH, the circuit that caused the fuse to blow is very likely shorted or at least has a clue to what's going on. I'd figure out if it's high or low beam, check the sockets at the bulbs and work my way back through the lines to see what you find. Having something shorting to ground or together inside a connector or the harness can fry your regulator too, especially if it the problem is not a fused circuit.

Intermittent electrical problems are the worst. Sometimes it's better just to have a fried part, harness section or whatever so you can repair it and move on. Only problem is, as John says - this can also result in a smoldering pile of <former> car.
 
Yes, wiring problems can be a nightmare. I agree with the above replies and suggest checking to make sure that the Voltage Regulator has a good ground and then visually checking the wiring to the Alternator and Regulator very carefully. You could also do continuity tests on each wire in the Alternator/VR circuit, although you'll have to disconnect the wires from them for that.

It does seem like the VR is either defective or just working intermittently, possibly because of a bad ground, loose connection or shorted wiring. The colored wiring diagram is a good idea, but hopefully some PO didn't splice in lengths of different colored wire, as is very often the case with 45 year old vehicles. I would also closely inspect the ignition wiring (to the coil, etc.), since it is connected to the VR wiring and a short there could affect the Charging Circuit.

A short in the wiring in the Charging Circuit, at the alternator or in the wiring to the Voltage Regulator, could cause the VR to be bypassed resulting in the alternator's field not being regulated. The Alternator would produce full output voltage, maybe 18, 20 volts or higher. So, again, I would check that wiring very carefully.

I hope you solve the problem. :)
 
To all -

THANK YOU for the input. At the moment, it's Friday early evening, I have a few drinks in me, and I'm in no mood to crawl under the hood or dash, but I PROMISE I will early next week.

I will follow everyone's advice and see what I can find.

HOWEVER! - I had a thought, please tell me what you think.

I looked at a schematic of the wiring I found online a few days ago. It seems as if the circuit for the VR has a wire from the alternator to the field terminal of the VR, and the other end of the VR goes to the ignition switch, please correct me if I'm wrong.

My ignition switch is very loose. I can insert the key and turn it, but it doesn't always "catch". Sometimes I have to push it in/wiggle it, in order to make it catch.

Could I have a grounding issue in the ignition switch? Would grounding the ignition end of the VR in the ignition switch cause it to stop working and send full, unregulated voltage to the lights?

Just a thought....

Thanks, and I'll dive into in early next week.

Chris
 
What year car is it? On most cars the ignition lock cylinder is separate from the ignition switch so a loose lock cylinder wont cause a electrical problem
 
Sporty - It's a '68. It has a separate lock cylinder that's loose, but I don't know the condition of the ignition switch itself.

Been doing a LOT of reading and research, and need to check that I understand the charging system correctly...please tell me if I am wrong...

As I understand the charging system, current flows FROM the ignition switch, through the VR, and into the field, and through to ground. The VR regulator senses the draw from the electrical system and the battery, and adjusts the current going to the field according to the draw, thus changing/adjusting the output of the alternator to match the demands of the system. Is that correct?

Another question - From what I've read, early (round back, which is what I have) Chrysler alternators came with 3 different amerage outputs, mid 30s, mid 40s, and 60. How do I find the amperage output of my alternator? I want to make sure that I have the correct VR in place.

Thanks...

Chris
 
Yes, You described the basics of the charging system. Except, Vreg does not sense "draw" (implies current). All it senses is the voltage difference between its supply (IGN from key switch) and its case. It tries to keep that at ~14.2 V. If it senses less, it increases the voltage (and hence current flow) to the alternator's field terminal. The other alternator terminal goes to ground (if a round-back). To be totally legalistic, a few 1970's round-backs came w/ the later "isolated field" setup. BTW, you can use a later square-back alternator with your Vreg if you just ground one field terminal (either one), which many do to get more output (especially at idle).

Installing a Vreg meant for a higher output alternator would not be a problem, assuming it is a "grounded field" alternator. All I have seen for the later "isolated field" have a 2-pin triangular connector.

What usually causes over-charging is that Vreg senses a falsely low voltage. That could be from voltage drops in the IGN wire to it (corroded bulkhead connector?), or from voltage drop in the return from case to BATT- (rusty sheet-metal screw?).

If you still have the original "mechanical Vreg" that switches mechanical contacts on/off, those can stick closed, thus causing over-voltage. You can get an affordable electronic Vreg ($11 rockauto for mine). Easy hook-up w/ same terminals.

Finally, in addition to your very useful dash ammeter, get a cigarette lighter voltmeter to monitor as you drive. I have a Eqquis (or such, $15 Amazon) I use in my modern cars on road trips so I'm not "flying blind" on charging. Harbor Freight has a $5 one w/ just LED's that works OK.

This topic is discussed ad infinitum on the A-body forum and asked several times per week. Searching is easiest from google. Your car has the same charging parts as any other Mopar of that year.

Finally, if you wonder why the 2 types of field control. The early mechanical Vreg did "high-side switching" and the 1970's electronic Vreg did "low-side regulating". It is easier to control low-side with transistors and about all they could do then. Today, it is trivial to control high-side too, hence you can get an electronic Vreg that works with your wiring.
 
"All it senses is the voltage difference between its supply (IGN from key switch) and its case. It tries to keep that at ~14.2 V. If it senses less, it increases the voltage (and hence current flow) to the alternator's field terminal."

Bill - Thank you for the reply.

Can you please explain to me the current flow through the mechanical VR? I'm a bit unsure as to what supplies the power to the case, and how the VR actually varies the current. My understanding is that it uses some type of bi-metallic strip, but I'm not sure of the inner workings.

Thank you.

Chris
 
Bill - Thank you for the reply.

Can you please explain to me the current flow through the mechanical VR? I'm a bit unsure as to what supplies the power to the case, and how the VR actually varies the current. My understanding is that it uses some type of bi-metallic strip, but I'm not sure of the inner workings.

Thank you.

Chris[/QUOTE]

I think I may have found what I'm looking for...

Reg.jpg
 
it will work with all three. The main difference is make sure you have a pre-70 alternator. The 70 and up have two plug-ins on the back, Instead of one like the 68'. A symptom of mixing them up is overcharging at high RPM, and discharging at Idle. The 34 is slant six mostly, 48 and 60 usually with factory A/C and options that require a higher load. It sounds like you have a dead short, either behind the Ignition switch, or headlight switch. You said you messed with the dimmer. once that three pronged plugin melts, those normally separate wires will Interact. All the lights would blow,fuses, etc. Unplug the dimmer, and start over. Like mysinbin said, learn what is working, and fix what Isn't.

I Didn't see billgrissom's post before I posted, but it is very good advice. he knows what he is talking about.
 
Ok...this is becoming clearer now, and I appreciate all the help. One additional point of clarification -

I understand that if there's a voltage drop in the ign wire to the VR, due to a bad or dirty connection, the low voltage level will cause the heating coil wrapped around the bimetallic strip to NOT heat up, thus keeping the contact points closed, and current flowing to the field, leading to an overcharge condition.

Is the current that flows from the ign wire through the heating coil the same power that flows through the points and into the alternator's field, thus controlling the alternator's output?

The reason I ask is because I've read that a ground or bad connection at the ignition switch or wire would lead to an overcharge condition. However, if the current that flows through the ign wire into the heating coil, through the VR points and into the field was stopped due to a broken or grounded ign wire, wouldn't that mean that no power was flowing into the field leading to a no-charge condition?

Yes, there would be no current flowing into the heating coil, and the points would remain closed, but there would also be no power flowing into the field through the broken/grounded ign wire.

I'm sorry if I'm confused or not completely understanding the charging system, but I'm trying...

Thanks...

Chris
 
Had some time to dig into it a bit more today.

The VR is properly grounded, and the IGN and Field connections are tight and clean.

I have continuity from the Field wire at the connector to the alternator.

The alternator will NOT charge with the field wire disconnected (looking for a possible internal short)

Here's where I think the problem lies - the voltage at the IGN wire at the VR never varies regardless of engine speed...it stays at a constant 11.9V, so the VR never varies the current to the alternator field.

I'm trying to trace through the wiring diagram to figure out what would cause the VR to receive constant current. Possible short or bad connection that feeds the ign wire constant voltage?

I know that the ammeter on Chryslers is a weak point...I've seen mine work sporadically, but that's it. Could the ammeter be causing the issue?

Still trying to figure this out...

Chris
 
BTW, here's a pic of the back of my alternator. Shouldn't there be a connection from the bare terminal to ground?

alt.jpg
 
That connection is grounded to the case. If it wasn't, the alternator would not charge.

FWIW, that alternator is a square back, 1972 and up version. The rebuilders use that style and adapt the field connections as needed. If it was a 1970 or later, that connection would not be grounded and you would hook the regulator to it. Most likely they went to that style because it's easier to rebuild. The diode bridge is much simpler to change.
 
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