Fallout from a faulty voltage regulator.

[70 Cam Guy]

Has anyone lost their voltage regulator allowing the alternator to run wild charging? Did it toast any of your components?

I lost my regulator on the drive to JCCS down highway 5. Turns out it wiped out my week-old Facet fuel pump and yellow top optima. We diagnosed the regulator and battery on the side of the road. I didn't notice the fuel pump until I had time to start diagnosing the problem. It popped the fuse whenever I keyed on (no start). Figured out the relay was not to blame so now I have a new fuel pump installed.

While I was working on it today, I installed a ZX alternator and Dave's alternator plug from MSA. As a small review, the conversion plug is well worth it, very clean and completely painless. From a cosmetic viewpoint, it made my soldered jumpers look mickey moused and lame. Voltage is not going above 14.5 but it seems high at idle.... still 14+... not sure if it's due to a slightly drained battery or something else. The alternator was just rebuilt by an auto-electric shop we've known for years. The amp meter in the dash looks very steady, a couple needle widths into the positive and holds steady with the headlights.

As the cob webs were blown out of the exhaust and engine warmed up (it was sure nice to hear it rev freely again), I started checking the amp gauge and loading the electrical system. As I tried to load the alternator, I noticed more systems are inop.

Apparently I have no turn signals, hazards, heater blower, or parking brake warning light. The head lights work. I haven't checked fuses with a meter yet but they 'look' ok. I'm worried the over-voltage didn't pop the fuses and took out some components. Anyone have experience with that?

It was getting dark so I decided to call it a day. Tomorrow I will be checking fuses, and likely looking at things under the dash :stupid:

/rant off

[DeesZ]

I had a VR go bad on me and it burned out all lights (dash included) except the headlights. Actually it popped all circuits that were on at the time of the voltage spike. It was dusk and I had the parking lights on but not the headlamps. It also fried my fusible link..... battery croaked several months later. Check the bulbs and whatever else was "on" at the time as a starting place for your inspections.

[260zCaliCar]

I suppose this question will put my knowledge of electricity out there for everyone to see, but why is a faulty VR blowing things like bulbs and fuel pumps out? I would have guessed that it might blow every fuse first. Is it that it takes more voltage/current to blow a fuse then it does to blow these components? Or does a fuse protect from to much of a "draw" as opposed to a "push" (for lack of the appropriate description). Just curious.

[70 Cam Guy]

I had a VR go bad on me and it burned out all lights (dash included) except the headlights. Actually it popped all circuits that were on at the time of the voltage spike. It was dusk and I had the parking lights on but not the headlamps. It also fried my fusible link..... battery croaked several months later. Check the bulbs and whatever else was "on" at the time as a starting place for your inspections.

Thanks! Unfortunately, everything that I had on when the car lost power is now what is not working (fuel pump that is on with the key, hazards as I pulled over, heater blower was on for fresh air, parking brake when I stopped). I am hoping the fuses are the culprit. I will definitely check the turn signal bulbs. Thinking out loud here, our bulbs are dual filament bulbs so I can see why the parking lights work when the flashers do not. I am not sure if the flasher unit will even work without any good bulbs (no load)

Will update later today as I hopefully find more answers

[70 Cam Guy]

I suppose this question will put my knowledge of electricity out there for everyone to see, but why is a faulty VR blowing things like bulbs and fuel pumps out? I would have guessed that it might blow every fuse first. Is it that it takes more voltage/current to blow a fuse then it does to blow these components? Or does a fuse protect from to much of a "draw" as opposed to a "push" (for lack of the appropriate description). Just curious.

Essentially the voltage regulator limits the charge voltage of the alternator. When the regulator fails as mine did, I was seeing 15+ volts at idle and even higher with the engine revving. Electric motors (fuel pumps, heater blower motors) will turn faster with more voltage, and bulbs will burn brighter like the headlights at higher rpm. There is a threshold though where the excessive voltage causes a failure (likely from heat in electric motors). I had been on the road for 120 miles already so all that time on the freeway overcharged the battery to a point that it probably discharged and no longer held a charge. It was showing 1 volt! Yes, I did have my multimeter with me

Anyway, IIRC voltage is considered potential energy and current is the flow of those electrons. You might think of it like a large river with a very slow current (large voltage, small current (amps)). You can also have small streams from, say, snow runoff that are small in relation but flowing very fast. Current is what is really dangerous to us. Stun guns operate at 50K volts but very little current (probably less than a mA). 110 volts is small in comparison but a 20 amp circuit in our homes will pack a deadly punch.

I hope this helps you somewhat, Electricity is hard for me to explain because what makes sense to me is sometimes hard to communicate. I know current pops fuses but I don't know if a high voltage across a fuse will create enough heat for it to fail. Thinking in terms of Ohm's law, DC Current = Voltage / Resistance, a voltage increase with no change in resistance will result in higher current. Was that enough to pop the fuse before part failure? I don't know tbh

[260zCaliCar]

Thanks Cam Guy,

Your explanation was very clear. Even though (honestly) I already knew that aspect of electricity. We both get stuck at the same spot in our understanding based on your comments which I have quoted below. I suppose we got the answer based on your experience... You didn't blow many fuses, but did blow a bunch of components (bulbs and fuel pumps) all of which theoretically were protected by fuses.

I know current pops fuses but I don't know if a high voltage across a fuse will create enough heat for it to fail. Thinking in terms of Ohm's law, DC Current = Voltage / Resistance, a voltage increase with no change in resistance will result in higher current. Was that enough to pop the fuse before part failure? I don't know tbh

[FastWoman]

Andy, the VR in my '78 alternator (internally regulated) was slowly going bad several weeks ago. The regulation point kept climbing, until it reached 16.25 V one day. I ran my headlights on the way home to drag down the voltage a bit. I had a replacement alternator installed the next day. Anyway, my 16.25V didn't seem to blow anything out. Even the battery was fine. Maybe I was just luckly.

Bulbs are probably going to go out long before fuses. Fuse values are appropriate to wire sizes, which are (usually) much more than adequate to feed the bulbs.

FAIW, 14-14.5V is a good, normal charging voltage.

[70 Cam Guy]

Thanks Sarah for the confirmation, too many charging problems with this car to want to take chances with voltage again.

Today's findings:

1 blown fuse: radio's 2A bus fuse

All turn signal/hazard bulbs were blown including brake bulbs. Dash bulbs that were 'on' at the time blew, and partially melted the sockets they are mounted in (both turn signal indicators and parking brake). That is not going to be fun. I'm not sure how to make more room for my hands (found new sockets at Pep Boys that fit the holes)

I keyed on and turned the heater switch to 4. Using my test light, it looks like no voltage is getting to the blower motor (red lead). My next stop is to try and get the instrument control finisher removed to get to the heater switch. I have the (stock) radio knobs removed, radio face, heater switch knob removed and 4 mounting screws removed. The finisher is loose now but it doesn't want to come out for some reason. The FSM doesn't have explicit directions to remove this panel but the couple exploded views don't show anything else that might be holding it on, except maybe 1 screw from behind. Going to have to search on this I think unless someone knows? While I was looking from behind, it looks like a couple wires were starting to melt together.

Doing wiring doesn't bother me too much but I really hate working under the dash, too many sharp edges :stupid:

Edited November 2, 2009 by 70 Cam Guy

[FastWoman]

If you have the original radio, it wouldn't have any special power supplies. It can deliver to the speakers however much voltage is supplied to it. More voltage means more current means you can easily blow that 2A fuse. I'm betting the radio is still good, though.

I'm very surprised at all the carnage in your system. Are you sure all the alternator was putting out was 16+ V? Melted wires (especially) shouldn't be happening. You should check your fuse values to make sure they're correct.

If your instrument panel is laid out like mine (1978), your turn signal and brake lights are in the tachometer. The easiest way to get to it is to remove the tach. There's a screw on the top of the bezel, just in front of the lens, and there's another one maybe a foot deeper on the bottom side, underneath the dash. Once those are removed, the tach pulls out through the front of the dash. The speedometer unscrews the same way, but of course you have to undo the cables through the tachometer hole before you can remove it. The smaller gauges are accessed by removing the blower face plate (term?) and then unscrewing them individually.

Good luck!

[70 Cam Guy]

Thanks,

We were seeing 15-16 volts on the side of the road. When we revved it we saw it spike to 32 volts for a second :eek:. I don't think it was sustaining that but I am sure that will easily smoke some components. I wonder if a sustained 15-20 volts could gradually heat the wiring to the point of softening the insulation. I could only see one wire indenting the insulation of the power white/red. (couldn't reach it)

Good call, I will verify the fuse values on my next work day. The fuses are all seeing 12 volts with the key on

I just looked at the service manual and you're right, it doesn't look that difficult to remove the speedo and tach. They each have 2 nuts on the back side of the gauge. The actual bulb sockets in the tach are 1 wire, grounding on the gauge chassis so they won't be hard to replace. I might try an under dash solder on the single wire (face shield a must) but I'll see how I feel when I actually do it.

still a good amount of work to do

Incidentally, I discovered today we have a dimmer on our gauge lights as I was looking through the FSM today. I have never even noticed the knob till today!

[Zs-ondabrain]

I'm sure it's been said but "The voltage will not blow the fuses, the amperage will." Unfortunately, if the amperage did'nt climb, the fuses didn't blow and the voltage was allowed to flow. And even worse, if you have my upgrade harness's in place, the high voltage is still allowed thru the fuse and directly to teh circuit, where-as a stock weak system with bad connections and wiring would have slowed the damage a little bit more.

So as ws said earlier, if it was on during the faulty mishap, it's a likely candidate for damage. (heater, lights, turnsignals, etc.)

Before you rip the dash plate off (heater control) check for the heaters motor fuse on the right side of the dash in that bundle of wires. The fuse holder typically melts under normal usage but your VR issue may have totally killed it. If it's melted (the holder) just cut it out and replace it with an aftermarket inline fuse holder (12 gauge with ATC Blade type fuse works fine.

Glad to hear the new alt and ZXP went in good. at least you're on the right path now. Think of it this way, you wanted to change those old bulbs out anyways. Right? Maybe? Hope your arms are skinny, that underdash area is a b i t c h.

[70 Cam Guy]

Thanks, Dave!

Thankfully(?), I haven't gotten around to the harness/relay upgrades. Since I did find a socket that will work in the tach and speedo holes, I am less worried, though not thrilled about tackling that. I am trying to stay positive and be patient with this

There are 3 inline bus fuses on the right side of the center console, 1 for the radio and 2 others that I don't know where they go. The 2A radio fuse was blown and the other 2 tested 0 resistance. Is there another fuse I'm missing that's over by the hazard flasher and the body harness connections (the right kick panel)?

I pulled off the red lead to my blower motor to probe the harness side with my test light. With the key and heater switch on, I wasn't getting a light on my probe. The fuses in the panel had 12V with the key on. I was thinking the resistor pack failed but it looks like the heater switch is the blower control. I am also not seeing anything on full blast. I didn't think to check voltage on the other inline fuses. I tested my ground using the radio lead. Lots of things to check, and maybe check again.

The big bummer is this car has 51K miles, and before this, the wiring was perfect. Nothing under the dash is dry or cracked. The heater ducting is even still squishy/springy.

I'm no body builder but my arms aren't very skinny. I have mini bruises everywhere, the red scratch lines are starting to fade finally, and the cuts look to be healing already. My hands barely fit in this dash

Everyone, thanks for your help!