Alternator wiring

Deano

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I removed the alternator to have it tested. Tested good. Battery gauge is bouncing and all lights (exterior and interior) are pulsing at idle. I'm hoping that I have reconnected the wiring correctly. I'm not real worried about the battery to alt wire, but how about the blue and green? Are they correct, or do I have them backwards? There's also a threaded hole on the front of the casing (black arrow) that says "grnd". What does this connect to or is it necessary?

This is not a pic of my alt.



71XROdN3JVL._AC_SL1500_.jpg
 

volare 1977

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Has the regulator been replaced or been tested? Sounds like a issue ( short) in your wiring though. I think my blue wire on my car is on the top terminal but believe the plug can go either way from what I remember. Others here would know for sure. BTW, check under the dash at the base of the column and see if any of the connectors or wires are melted or burnt.
 
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Hayzoos

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The blue and green connections are reversible with no change in performance. The gnd is not used in any installations I have seen. The alternator grounds through the mounting bolts to the engine block. The engine block is connected directly to the negative battery terminal. The regulator grounds through it's mounting bolts to the firewall (body) there is a grounding strap between the engine block and the body. I mention all this because the whole charging circuit relies on good grounding. So all points I mentioned should be checked for good contact. Steel will rust and introduce resistance into the circuit and interfere with proper charging system operation. BTW copper corrosion is nearly as conductive as copper itself so don't waste time cleaning copper corrosion. Also check for good clean connection at the battery posts, lead corrosion does introduce resistance.
 

Deano

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Bought a new battery about a month ago and just put a new positive/ negative cables from the battery to engine block/ inner fenderwell a few days ago. I'll try a new voltage regulator in the coming weeks.

Where is the ground strap from the engine to the body? I haven't seen one, but I really haven't been looking for one, either.

The battery gauge doesn't bounce a lot. It stays on the center mark, but still pulses.
 

BudW

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There are two ground wires to engine. One is a large one going straight to the battery:
20170803_114522 a.jpg

Sometimes the connection to cylinder head gets rusty, so take the time to remove the bolt, wire brush the terminal (as well as head and da bolt) and reattach to cylinder head. Sometimes the battery terminal needs cleaned. Sometimes the battery cable (negative) can go bad over time (or corroded, etc.).

On back side, there will be a secondary ground cable (pink arrow):
20170803_114551 a.jpg

These are often left disconnected after engine repairs (or missing). Most of our cars, this is a bare braded stainless-steel cable (like this one). Again, sometimes the cable needs to have ends cleaned (for rust or corrosion) or when reattached to a fresh engine, one might need to scrape off engine paint to get a good ground (just like above).

When Chrysler built these cars, they attached the negative battery cable onto engine, then painted the engine (so part of cable got painted) - just to make sure there was a good electrical connection.
340 Paint a.jpg

White arrow.

BudW
 
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Aspen500

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We used to add a ground wire from one of the regulator mounting bolts to the engine on Mopars at work, just to be sure the ground was good. Pulsing lights at idle is often caused by the regulator. The problem anymore is finding a good one. I had an automotive instructor who always said "new just means new, it doesn't necessarily mean good", and I'll be darned if he wasn't right.
 

BudW

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I have always wondered why Chrysler didn't attach the rear engine ground wire directly to the regulator (which makes the most sense). Later found out Chrysler attaches the rear ground wire onto the engine before install and voltage regulator (and underhood wiring harness) is (also) installed (to body) before engine install.
The rear ground wire is just a couple of inches too short to reach to the voltage regulator.

Not mentioned, but the voltage regulator ground might also be an issue.
If you still can't find the problem, maybe making a short jumper wire and bolt to voltage regulator base to the rear engine body ground bolt might help. Grounding items to body - when there is paint in the way, doesn't do much for long term and trouble-free grounding.
BudW
 

Mikes5thAve

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Sounds like a ground. Could be regulator or its plug. Telltale sign of bad regulator is lights go dim at stops and bright once you speed up.

There is also ground on the bottom back of the engine on the passenger side that clips to the k frame.

A lot of 88/89s ive seen have a short insulated ground cable that goes from alternator to intake. I don't know if mine did or not because I didn't do anything with that 318 before pulling it out but I've grabbed it from a couple cars now.
 

Deano

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Seems like a jumper ground from the VR case to the block would be easiest and quickest. Hoping it'll be that easy. Probably not.
 

Deano

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What would be a good way to check for good ground? I have a multimeter that has continuity selection. Touch the VR case with one probe and say, the engine block with the other?
 

Aspen500

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That would work. A better way is to use the volt scale with the circuit energized. Touch one probe to the regulator case and the other to the neg battery post with the engine running. You should see less than 0.1 to 0.2 volts. Much more than that means the meter is providing additional grounding.

Basically, a ground ckt with continuity doesn't mean it's sufficient with the ckt under load.

Hope that makes sense the way I tried to describe it. I've run into this many times at work where a ground ckt that checks good with ohms, fails when the load is applied. It's similar to checking supply voltage with the load on and checking connections using a voltage drop test. There can be 12 volts at the terminal but when the load is on, there will be none, which means the wire can carry voltage but no amperage.
 

ChryslerCruiser

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I don't have enough technical experience to voice any suggestions regarding electrical troubleshooting and repairs...

I can say that my experience with a new "Standard automotive parts" voltage regulator was disappointing. I eventually ended up getting an "adjustable" voltage regulator from Ebay, and it worked correctly the with out me doing any adjusting. Just plugged it in, and the problem was solved.

Your results may vary, but I am going with the adjustable type VR from here on.
 

Mikes5thAve

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When all else fails you can try temporarily adding grounds to see if it makes a difference. Strip the ends off a wire and stick one end under an engine bolt and the other under whatever convenient screw or bolt is on the part you think is having problems. The voltage regulator, alternator etc.. make sure it's a part that's supposed to be grounded and doesn't have + power. A wire with clips on the end is even better. Make sure ground from battery to engine is good first.
 

AJ/FormS

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An Ammeter indicates which power source is powering your car, either alternator or battery.
The regulator is there to Command the alternator to maintain a slightly higher output-pressure (voltage) than the battery.
If the ammeter is bouncing on the switch-point, it could simply be because the idle-speed is too low. But if it continues to bounce as the rpm increases, something may be wrong.
The Regulator has the primary job of sensing battery voltage, and maintaining the battery at a predetermined voltage. It does this by turning the field coil on, and checking the voltage again. When the voltage goes over it's set point, it shuts the field coil off, and checks the voltage again. Then when the voltage falls, it turns the field coil on again. It does this continuously at a high rate of speed, and so a sensitive ammeter will show the handiwork of the regulator.
Usually the ammeter is electrically damped, and kindof a slouch. But in your case it seems not to be damped at all. No big deal; I think.
But to be sure, you should do an Amp-Draw test, to rule out an inordinate power draw, or a short, somewhere in the system. The heater is often a major player, with the headlight circuit coming in a close second.
 
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