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Electrical Nightmare

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#1 Blueheeler


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Posted 16 April 2018 - 05:47 PM

Think I've got the car from the devils den. I bought this 72 Monte in Dec. & have pretty much spent time everyday working on it to make it road worthy. My Mom just had knee surgery & needed my assistance for a few days to help her during her recovery period. I thought it'd be a great opportunity to drive the Monte back home & show my old buddies my pride & joy. On the way down when I stopped for gas I noticed a rotten egg odor. Try as I might I could not find a cause or the source off the smell. I just told myself maybe the cars running to rich & that's what's causing the odor. That was a big mistake on my part. A few hundred miles later the car just died. Upon opening the hood smoke was pouring out of the battery. Had no choice but to have the car towed to a local repair center. Two days later I was shocked at and for the 1st time started to regret ever buying the car. Many of the items I had just purchased & replaced were now trash. Based on the info told to me by the repair shop in 1972 the Monte had a alternator & a voltage regulator. Starting in 1973, all GM alternators now had the regulator built internal, therefore a separate regulator was not needed. At some point in time, the original alternator on the car failed. The replacement alternator was the new style which had the internal regulator. That meant the external regulator should have been removed & the wiring at the regulator modified. That was never done. As a result, the alternators internal regulator & external regular fought each other. The result was the alternator kept charging the battery & just cooked it plus other electronics. Here's the list of items lost, Battery, distributor, radio, tachometer, amp gauge, TomTom navigation unit, remote trunk latch. I'm wondering if other electronics were damaged too even though there now working. Per the repair shops recommendation (no time to really think about it) I agreed for them to switch the alternator from a 3 wire system to a single wire. Also had to installed a new distributor, & battery just to get the car back on the road. So far so good, seems to have done the trick. I will be leaving Cincinnati in the morning & heading back home to Danbury CT. so I suppose the real test is soon to happen. Hopefully by reading this maybe someone else will be spared what I'm going through.

#2 Rock


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Posted 16 April 2018 - 06:04 PM

Yeah, that totally sucks. When ever we add an internally regulated alt the VR needs to be by passed. How much of the wiring was sacrificed? Can you just buy the hood harness?
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#3 Mo's70MCs


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Posted 16 April 2018 - 08:13 PM

Count your could have been worse, a small spark near that overcharged battery and everything in the vicinity would have blown to smitharings.


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#4 Andy's Auto

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Posted 17 April 2018 - 05:33 AM

  I get alternators my parts guy calls the swamp buggy units. One wire and done, as long as you wire the big fatty on the post on the rear of the unit directly to the battery. Never been a fan of amp gauges. Even my restored 70 SS454 Chevelle is not  wired for the factory amp gauge.

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#5 Blueheeler


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Posted 18 April 2018 - 11:20 AM

To the best of my knowledge I didn't melt any wiring but I sure did fry some electrical components. While I'd like the amp meter to work I can live without & if I can figure it out always mount a remote voltage gauge. Losing the other items is a killer, especially since most were brand new, like the trunk latch, & stereo. But by far the biggest loss was the tach. I really don't want to pull the dash again. I keep hoping since the distributor was replaced & upgraded & switching the alternator from a 3 wire to single wire and removing the voltage regulator that maybe the tachs still good & I just have something miss wired or not connected. Trying to look at the wiring diagram is extremely difficult & confusing. For now the cars just sitting as I've found it's not a good ideal to work on it when your in a bad mood.  

#6 monte70car


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Posted 19 April 2018 - 04:31 AM

Now if i understood correctly you said you have a 72. My understanding is in 72 the voltage regulator was internal. Now I could be wrong and miss understood the person. I know my 70 had an external voltage regulator which was removed for a one wire alternator which was then wired up as a three wire alternator. My 72 was brought as a roller but there was no regulator on the core support nor the firewall. If the battery leaked that sounds like the alternator was over charging the system to me. Not sure on what tach you have but if its the stock gauges you could have burn out the PCB on the cluster. There is fuseable links built into the harness which is supposed to burn out before any damage is done to the electrical devices. I've re-wired cars, moved cars over to 1 wire alternators then convert them to three wire as there is an internal regulator that you can access by removing a plug.  



#7 Leghome


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Posted 19 April 2018 - 07:44 AM

My 72 had a regulator which went bad and now have a 100 amp alternator with one wire hookup and an internal regulator. It only cost me $54 to get my old one rebuilt and changed over.

Edited by Leghome, 19 April 2018 - 07:45 AM.

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#8 cbolt


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Posted 19 April 2018 - 03:55 PM

My 72 was externally regulated. I swapped to a 1 wire setup a long time ago and have had no issues. Those stupid external regulators fail pretty consistently and always at the wrong time. Those of you who know me know I drive my car often. I cannot have an unreliable externally regulated charging system.

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#9 Blueheeler


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Posted 19 April 2018 - 07:20 PM

The real problem here is that I have very limited mechanical knowledge. I just swap a part for a like part. I was completely unaware & never thought that changes needed to be made. As a teenager in high school I worked at a gas station pumping gas & working on my own car but that was many years ago. One of the reasons for buying the car was to recapture some of my youth & have some fun fixing up a older car. It's beginning not to be so much fun & I'm starting to think that it might be cheaper in the long run to just drop the car off at a repair shop & let them fix it.

#10 Rob Peters

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Posted 19 April 2018 - 07:37 PM

There is a ton of information here on the site. by asking questions here and all over the internet.  Many of us here have learned by doing.  Never be afraid to try to fix something yourself, that is how you learn.  The more you learn, the easier things will bet to be to fix in other areas of the car.  A lot of things in troubleshooting a problem is pure logic.  The more you can repair yourself the more money you will have to spend on other areas of the car.  When you get frustrated, take a break.... or throw a wrench across the garage (just don't let the Monte, a human or another vehicle be in the path of the flying wrench.  Sometimes adult beverages help in repairs but not always.


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#11 cbolt


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Posted 20 April 2018 - 01:59 AM

Tom, no need to be upset just yet. Let's think about this in small portions rather than a big problem. I assume you made it home in the car okay? Are you only missing the tach, stereo, trunk pop, and ammeter? If that is the case you can tackle one at a time. The stereo issue may simply be a blown fuse. The tach and ammeter may be related, so ask yourself if the tach and ammeter were working up until the car died. The ammeter feeds off the voltage regulator, and if you swapped to a 1 wire it may not work if I am not mistaken. The tach feeds from your distributor and you may very well have neglected to install the feed wire on the new distributor correctly. Retrace your steps there for starters.


I am not familiar with the trunk pop system so I cannot steer you in the right direction there.


Trust me when I say I love working on cars too, but have had many, many days of frustration while troubleshooting various issues. I don't like venturing behind the dash either, however had done it so many times out of necessity I could write a book. Ugh. My advice to you is step back, take a deep breath, and just think about what you have and decide the best first step. Like Rob said, there is a wealth of knowledge here on the site. All you have to do is ask.

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#12 overdrive


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Posted 21 April 2018 - 05:43 PM

Sorry that you had this problem. It must have been daylight. You didn't mention any problems with light bulbs. I would expect bulbs to blow when the voltage gets too high. I would not expect the fuses to blow. When voltage goes up, current goes down, as long as the load (resistance) stays the same. The fuses would have less current passing through, not more, and should be fine. Any time you smell sulphur, or the rotten egg odor near a vehicle, that's a definite indicator that the charging system is overcharging the battery. It's the gases from the sulphuric acid in the battery.

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