All4EA81 Posted December 18, 2009 Share Posted December 18, 2009 (edited) I think its just a coincidence, but as soon as i put my dash back in my alternator started to act up. I was driving down the hwy at night with my brights and heater full blast and i noticed my volts were slowly starting to die off. At the start of the trip they were about 13.5-14 volts, but by the end they looked to be down around 11 "according to the dash meter". I also noticed my charge light had a very faint glow. I inspected the alternator connections, and the terminal to the battery burnt me. It was putting out voltage at around 15+. I cant remember what the other two wires were at, but none of the voltages were the same as i recall. I took my alternator to Napa and Schuck's and it passed at both places. I thought it might be wiring going to the charge indicator lamp so i pulled the instrument cluster and found that the housing around the bulb had gotten hot enough to start to melt "although it still appears to be functional". Also, if i traced the path of current once the wire connects to the board, it also runns into a few diodes that look to have gotten a little hot. What would cause the alternator to pump so much current? Has anybody else seen the lamp wire melt anything like this? Why did my alt pass inspection? TWICE? The day after, my volts meter started to jump around. I took my alt to Knecht's -and it failed- so I bought a new one, installed it, and volts seem normal. But my console volts meter is still jumping around. It looks like the meter is fed by the ign switch. Why would the meter be jumping around? Edited December 18, 2009 by All4EA81 Quote Link to comment Share on other sites More sharing options...
murph Posted December 18, 2009 Share Posted December 18, 2009 wow , that is wierd , my 81 wagon has some strange stuff going on with the electrical system too . i've melted all kinds of things - the high beams cooked the fuse box one night . she's still takeing me to work when i need her to ! good luck , i can't offer much advise other than grounds seem to very important on my wagon , i've had to clean and reattatch most of them , i've got some rust issues . murph Quote Link to comment Share on other sites More sharing options...
All4EA81 Posted December 18, 2009 Author Share Posted December 18, 2009 My guess is the voltage coming from the alternator was higher than the voltage coming from the ignition and it was able to force its way through the charge indicator lamp and ground at the volts meter. This would explain the faint glow from the lamp. The volts meter probably jumps now because too much current was passing through it to ground. What I want to know is how did this happen and why didn't the designated 5amp fuse stop it from happening? Should I be worried about it happening again after I replace the parts? So far I think I need a volts meter, a fuel gauge, and some new diodes. Who knows what else got affected. Why didn't that fuse blow? Quote Link to comment Share on other sites More sharing options...
heartless Posted December 18, 2009 Share Posted December 18, 2009 just curious - did you have the alt tested in the car, or did you pull it and take it in?? if you pulled it - put it back in, take the whole car over & have them check the whole charging system in car - alt, battery, etc...may not be the alt, but something else...testing in car can help narrow it down. Quote Link to comment Share on other sites More sharing options...
All4EA81 Posted December 18, 2009 Author Share Posted December 18, 2009 I just had the alt tested with it out of the car. Quote Link to comment Share on other sites More sharing options...
All4EA81 Posted December 19, 2009 Author Share Posted December 19, 2009 So I got a new alternator, instrument cluster, and ignition switch. Now my volts read a constant 14 at the battery, the alternator, and even on my dash meter. Only now my oil pressure reads sky high and my seat belt chime works. I'm still curious about the melted bulb though. If the alternator starts to pump too much power isn't that what the fuse box is for? Quote Link to comment Share on other sites More sharing options...
heartless Posted December 20, 2009 Share Posted December 20, 2009 So I got a new alternator, instrument cluster, and ignition switch. Now my volts read a constant 14 at the battery, the alternator, and even on my dash meter. Only now my oil pressure reads sky high and my seat belt chime works. I'm still curious about the melted bulb though. If the alternator starts to pump too much power isn't that what the fuse box is for? supposedly, yes, but it doesnt always happen that way. MY 89 GL had a similar issue once - alt overcharging - 18v! - and it didnt pop any fuses or fuse links - ran as many accessories as I could to get it home (heat full blast, headlights, foglights, etc) - lucky me had a spare alt just waiting to be dropped in. what do you consider "sky high" on the oil pressure?? fwiw - the stock oil pressure guages arent the best & are known to read funny... Quote Link to comment Share on other sites More sharing options...
murph Posted December 20, 2009 Share Posted December 20, 2009 i had high oil pressure one time because the wire from the sending unit grounded itself out on the crankshft pully ( i didn't route it properly ) i know now the sending unit wire grounded out will max out the gauge . maybe this info will help you ? good luck , happy holidays ! murph Quote Link to comment Share on other sites More sharing options...
All4EA81 Posted December 20, 2009 Author Share Posted December 20, 2009 My old oil pressure gauge read about 49 psi when fully warmed up. This gauge that came with the new instrument cluster reads about 67. And it takes a long time to settle into that range. When idling it only goes down to 50 where as my old one read about 25-30 as I recall. I'm going to check for any new shorts in the circuit then try swapping it with my old one. Quote Link to comment Share on other sites More sharing options...
heartless Posted December 21, 2009 Share Posted December 21, 2009 my old wagon would barely register when fully warmed up at idle - would read around 35-40 at highway speeds...50+ on cold start up Quote Link to comment Share on other sites More sharing options...
All4EA81 Posted December 21, 2009 Author Share Posted December 21, 2009 Well, it sounds like these old gauges are more for looks now a days. Maybe I can just wire up an accurate warning light and still keep the stock look at the dash. Isn't there a spot on the pump a simple sensor can be screwed into? Quote Link to comment Share on other sites More sharing options...
eulogious Posted December 22, 2009 Share Posted December 22, 2009 If the alternator starts to pump too much power isn't that what the fuse box is for? Yes and no on this. Power consists of two elements, volts and amps. Think of it like a water pipe. Volts is how big/wide the pipe is, and Amps is how much water/flow/pressure is going through the pipe. Just because something is putting out 18 VOLTS, it can still be drawing the same amount of AMPS, so therefore the fuse will not blow. So in this case your pipes(voltage) got HUGE, but the flow/pressure(amperage) stayed the same. Fuses don't provide protection for over-voltage situations, just for over-amperage situations, hence why your fuses didn't blow in your situation. Bad things happen when there is too much voltage applied, and also when there is too much amperage applied as well, and they can cause damage independently of each other ie just because there is a over volt situation, doesn't mean there will be an over amp situation as well. I hope that helps explain why your fuses are still intact. Quote Link to comment Share on other sites More sharing options...
heartless Posted December 22, 2009 Share Posted December 22, 2009 Yes and no on this. Power consists of two elements, volts and amps. Think of it like a water pipe. Volts is how big/wide the pipe is, and Amps is how much water/flow/pressure is going through the pipe. Just because something is putting out 18 VOLTS, it can still be drawing the same amount of AMPS, so therefore the fuse will not blow. So in this case your pipes(voltage) got HUGE, but the flow/pressure(amperage) stayed the same. Fuses don't provide protection for over-voltage situations, just for over-amperage situations, hence why your fuses didn't blow in your situation. Bad things happen when there is too much voltage applied, and also when there is too much amperage applied as well, and they can cause damage independently of each other ie just because there is a over volt situation, doesn't mean there will be an over amp situation as well. I hope that helps explain why your fuses are still intact. Excellent analogy!! certainly made it much clearer to me. Quote Link to comment Share on other sites More sharing options...
eulogious Posted December 22, 2009 Share Posted December 22, 2009 Excellent analogy!! certainly made it much clearer to me. Thank my EE (electronic engineer) buddy who explained it to me that way. Same analogy can be used with internet bandwidth and speed, but that's a whole other ball of wax I am glad that it helped, I know that it helped me tremendously in understanding the basics of electronics. Alot of stuff fell into place and made WAY more sense after hearing it explained that way. Quote Link to comment Share on other sites More sharing options...
All4EA81 Posted December 22, 2009 Author Share Posted December 22, 2009 So besides the voltage regulator, whats to protect your system from over voltage? A second regulator? If fuses protect from "pressure spikes" what can a guy do to stop a slow flood that doesn't have any push behind it? Quote Link to comment Share on other sites More sharing options...
eulogious Posted December 23, 2009 Share Posted December 23, 2009 Unfortunately nothing. I think the biggest reason is cost. It's super easy to make a fuse. The principals on how amps work and operate make it easy to create a fuse, and therefore it becomes very cheap to manufacture. A "surge protector", like the ones for computers, are ALOT more complicated in comparison. They are "simple" compared to computers, but complicated compared to a fuse, or even a circuit break, so therefore alot more to manufacture. Now in all honesty what has happened to you doesn't happen all that often. And when it does, it's not THAT hard to fix. It's a PITA, but doable for the "average" back yard mechanic. Alternators usually don't fail in the way you described, and when they do, it's not all that often, so I can imagine SOA decided that it was worth the risk and cost to fix it when it breaks, rather than put the R&D into developing a surge protector for the car, and then manufacturing it/stocking it/shipping it/etc. Also I know that most electronics are designed to operate with in a certain percentage of amps/volts for tolerance, since you can't always guarantee that the perfect operating conditions all the time. For instance, before you turn your car on before starting it, it's operating at around 12v, and when you start it, it's operating at around 14v, so the electronics are designed to operate within a certain range of voltage. With that being said, they can also take a little more for a brief period with being destroyed. I also know that most electronics DO have a built in safety, usually with diodes/resistors/capacitors/etc. Most likely one of those fried within yours, but it's just easier to replace parts, than it is to try to fix what went wrong within the circuit board. I also think that is one of the main reason why manufactures also put a volt gauge on the car, so you can see when something isn't correct. Most likely if you would have immediately pulled the car over and turned off the car when you first noticed the problem, you wouldn't have fried anything. I think the manufactures assume that if it doesn't act right, you will just stop to prevent damage. But not all of us stop when we should This isn't a dig at you or anything, just a matter of fact. I am guilty of doing this as well at some point Of course the manufactures could just make 2 voltage regulators in the alternator for redundancy, but again this comes down to cost versus risk, and the cost usually wins. What's good for the company, isn't always good for the customer... The simple answer is that it doesn't happen enough to warrant putting a surge protector in the car or two voltage regulators in the alternator, but it's totally worth it to put in a fuse box. Again, all of this is just my 2 cents... Quote Link to comment Share on other sites More sharing options...
All4EA81 Posted December 23, 2009 Author Share Posted December 23, 2009 Thanks for the explanation. It was exactly what I was looking for. I learned a lot from this thread. Quote Link to comment Share on other sites More sharing options...
heartless Posted December 23, 2009 Share Posted December 23, 2009 Me too! had a limited understanding of it, but the water/pipe analogy just made it crystal clear! Thank you! Quote Link to comment Share on other sites More sharing options...
eulogious Posted December 23, 2009 Share Posted December 23, 2009 I'm glad I could help! I love the internet and I have gained so much knowledge from it that the least that I could do is try to explain things the best I can to spread the knowledge some more. It's kinda like karma, the more I give, the more I can take I am not very good with the mechanical aspects of cars, I am learning , but electrical stuff I am good at and enjoy so I help where I can I am glad I could help you all out! Quote Link to comment Share on other sites More sharing options...
heartless Posted December 23, 2009 Share Posted December 23, 2009 I'm glad I could help! I love the internet and I have gained so much knowledge from it that the least that I could do is try to explain things the best I can to spread the knowledge some more. It's kinda like karma, the more I give, the more I can take I am not very good with the mechanical aspects of cars, I am learning , but electrical stuff I am good at and enjoy so I help where I can I am glad I could help you all out! altho i find the mechanical much easier to deal with, i can do electrical and am rather anal about it when i do - one thing i absolutely hate is a botched or sloppy wiring job!! call it karma, or whatever you wish - what goes around comes around I always say! i - like you - try to help where i can, altho i probably dont contribute as much as others can (& do!)!! Quote Link to comment Share on other sites More sharing options...
Cougar Posted December 31, 2009 Share Posted December 31, 2009 Just wanted to correct something about a statement that was made about when voltage goes up the current will stay the same. Unless Ohm's Law has changed at some point, whenever voltage is increased to a circuit the current has to go up also, it's the LAW. The higher current may not be enough to blow a fuse but it can damage electronic items that are designed to run at a lower voltage. Another thing can happen when the diodes go bad in the alternator and that is high AC ripple voltage. Not a good thing for the battery or electronics. Quote Link to comment Share on other sites More sharing options...
eulogious Posted December 31, 2009 Share Posted December 31, 2009 Just wanted to correct something about a statement that was made about when voltage goes up the current will stay the same. Unless Ohm's Law has changed at some point, whenever voltage is increased to a circuit the current has to go up also, it's the LAW. The higher current may not be enough to blow a fuse but it can damage electronic items that are designed to run at a lower voltage. Another thing can happen when the diodes go bad in the alternator and that is high AC ripple voltage. Not a good thing for the battery or electronics. I highly doubt that Ohms law has changed This is very true, I just didn't state it for simplicity sake since it doesn't really apply here, but very true. Thanks for pointing that out. In this case I don't think that the increase in AMPS brought on the failure since the fuses didn't blow, so I left that part out for that reason and not to confuse anyone anymore than need be. Good catch. Quote Link to comment Share on other sites More sharing options...
Cougar Posted December 31, 2009 Share Posted December 31, 2009 (edited) The fuses in the car are there mainly to protect the wiring and not say for instance, the radio itself. A single fuse supplies power to a number of devices usually on a circuit and can carry a lot more current than a single device on that circuit is designed to handle. It is also the excessive current running through a device that will cause it to be damaged if that current exceeds the design limits of the circuit. Of course this could be caused either by a higher voltage input or the failure of something else in the circuit causing higher current to flow. Having excessive voltage coming from the alternator is a bad thing but even worse is when the diodes go bad in it and that causes excessive AC ripple voltage. That can go real high it some cases and can really kill electronic devices. Edited December 31, 2009 by Cougar Quote Link to comment Share on other sites More sharing options...
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