Charging system issue

[73vertproject]

OK, I replaced the alternator harness with an NOS that I got a great deal on from Jeff73Mach1. It's beautiful.

But I must have forgotten something. I've started the car probably 10 - 15 times since replacing the harness, and last weekend it turned over kind of sluggish. At WalMart, it barely turned over once and wouldn't start. Got a jump from kind stranger and she fired right up. Drove home and wouldn't turn over.

I'll post up pics when I get home, but does the round steel tab near the alternator end of the harness need to be bolted to a ground or something? It's just hanging free in the air. I've got 12.07 volts at the battery right now, and haven't tested anything yet. Where to start?

New alternator, battery, etc. no squeals, everything new except voltage regulator.

 

[Mister 4x4]

There's a stud toward the 'bottom' of the backside of the alternator (as installed). The 'tab' thing bolts onto that stud, then the fat wire with the eyelet goes to the 'BAT' terminal, and the other goes to the 'FLD' terminal. (I had mine attached to the 'STAT' terminal, and no chargey - and I have no idea what the colors are).

Sorry for the over-use of technical verbiage. rofl

 

[73vertproject]

There's a stud toward the 'bottom' of the backside of the alternator (as installed). The 'tab' thing bolts onto that stud, then the fat wire with the eyelet goes to the 'BAT' terminal, and the other goes to the 'FLD' terminal. (I had mine attached to the 'STAT' terminal, and no chargey - and I have no idea what the colors are).

Sorry for the over-use of technical verbiage. rofl

LOL Eric. OK, I'll attach that tab to a stud on the back of the alternator. The fat wire is attached to the BAT with a nut, and then I have two skinny wires attached to FLD and STAT terminals with their press-in connector thingies.

Any testing I can do to determine if it works besides wait and hope that the battery charges?

 

[wwhite72]

I believe Painless has most Fords on their site...alt connections for almost all Ford V8 vehicles from the 70's will be the same: mustangs, torinos, cougars, pickups, vans....all basically the same. Painless wiring has color diagrams and details if you want to see them on the internet. And there are tons of reference manuals available if you want to keep one in the garage and get greasy prints all over it, which is also funny to keep.

 

[MechEng]

Round steel tab? Is this on your negative battery cable? The negative battery cable should go from the (-) terminal, the metal tab should then be secured to the chassis under the voltage regulator, and then the end of the cable should be bolted to the engine.

 

[73vertproject]

Here's a couple pics:



You can see the orange-capped wire but not the black-capped one down below. And you can't see the silver tab at the intersection of all the wires near the alternator.



Also, there are four male spades coming out of the VR, but only three female connectors in the VR plug. The fourth spot is a blank:





More ideas?

 

[wwhite72]

btw the rubber thing with the tab is called the "strain relief" by Ford. It absorbs the rocking motion of the awsome American V8 when you pump the throttle and make the engine shake under the hood! Fun hobby right?

 

[73vertproject]

btw the rubber thing with the tab is called the "strain relief" by Ford. It absorbs the rocking motion of the awsome American V8 when you pump the throttle and make the engine shake under the hood! Fun hobby right?

OK, thanks for the info. Sounds like it doesn't serve any purpose related to charging the battery, but I'll strap her down anyway.

 

[wwhite72]

I think it might serve a grounding purpose as well, but im not sure.

 

[73vertproject]

OK, update. Getting 12.18 volts at the battery terminals with the car running.

I forgot to hook this wire up, so that may be the culprit. Where does it connect to the solenoid area?

 

[MechEng]

That wire goes to the small silver box that should be on the always hot side of the starter relay. It is a main power line for your seat lock solenoids and some other high current sources in the car. Nothing to do with charging though I'm afraid. Does your car have A/C? I believe the VR connector was slightly different for models with and without A/C could explain the missing terminal in the connector.

 

[RacerX]

Sounds like you might have bad VR. Should have more than 12.18 volts. Rev it to 1500 while checking the charge voltage. Should see about 14.2 volts.

If not, jump wires 1 and 3 on the voltage regulator. This will make the alt. output max charge. If this works, VR is bad for certain. Don't leave this connected for long, will overheat the alternator.

 

[midlife]

There should be a ground wire attached to the alternator, and I believe that is what is not connected. Without that ground wire, the Voltage Regulator won't know what is being sent from the alternator for it to control it.

It is very common to have only 3 of 4 lugs on the VR plug, particularly if the car has an ammeter. 4 lug variants are used for the alternator idiot light in the dash.

 

[Mister 4x4]

There should be a ground wire attached to the alternator, and I believe that is what is not connected. Without that ground wire, the Voltage Regulator won't know what is being sent from the alternator for it to control it.

It is very common to have only 3 of 4 lugs on the VR plug, particularly if the car has an ammeter. 4 lug variants are used for the alternator idiot light in the dash.

OK, so even if the alternator harness doesn't have a ground wire included, we should hook up a ground wire from the 'GND' lug to a good grounding point? I'm asking because I'm also getting 12.8 (which runs up to 13.8-ish when the engine revs go up).

Also, wouldn't the chassis of the alternator serve as the ground? Or is the grounding of the alternator itself isolated from the alternator chassis itself?

Good stuff, guys!

BTW Doc: since mine's a '71, I only had 2 wires running through my alternator harness - which hyena's explanation over the weekend got me through (FLD vs. STAT for me). Apparently, yours has both - which I remember having both on my '82 Mustang (it used to eat Stators every 8 months or so... so I became proficient enough to change out its alternator in about 9 minutes).

 

[72HCODE]

i'm thinking pull the alternator and have it tested just to rule out that it is charging.

after that i would suspect the Voltage regulator and replace it. reconnect and then retest if the battery is charging.

if it still isn't charging then you ruled out the VR,Alternator and Alternator Harness, and the problem has to be on the main harness side maybe a broken wire at a connector point.

ground should be the engine block which has a ground connection back to the battery via the neg battery cable.

Now if you painted the engine or it was resprayed many people do not clean the paint off the contact points and then there is no ground. you may need to go back pull things apart and clean up the bolt locations of paint to get a solid ground.

you could check how solid the ground is using a continuity tester or a ohm meter. disconnect ground from the battery , place one tester on the battery ground wire and touch the other to the alternator body and if you don't get a reading then the ground isn't solid.

 

[wwhite72]

But if the alt is bloted to the block and the VR is grounded to the fenderwall and the battery neg cable its gotta be the harness, either a broken wire or the contacts. You can replace the alt harness for cheap. Or do the meter testing and sandpaper and solder.

 

[midlife]

Ground lug on alternator is basically on the chassis of the alternator. DO NOT count on the mounting of the alternator to the engine to act as your ground point, as it is not secure enough (electrically). The other important grounding point is the voltage regulator: make sure the paint is scraped beneath the ring connector that goes between the VR flange and the fender apron.

 

[MechEng]

Ground lug on alternator is basically on the chassis of the alternator. DO NOT count on the mounting of the alternator to the engine to act as your ground point, as it is not secure enough (electrically). The other important grounding point is the voltage regulator: make sure the paint is scraped beneath the ring connector that goes between the VR flange and the fender apron.

I can attest to the importance of this. I had a bad ground to my chassis because of repainting the fender skirts and not cleaning the contact area. Real pain in the but because it messed up a bunch of my cabin electronics even though the car ran alright. Use a little of the terminal grease too, helps prevent moisture from getting in there and corroding the bare metal.

 

[Mister 4x4]

Ground lug on alternator is basically on the chassis of the alternator. DO NOT count on the mounting of the alternator to the engine to act as your ground point, as it is not secure enough (electrically). The other important grounding point is the voltage regulator: make sure the paint is scraped beneath the ring connector that goes between the VR flange and the fender apron.

Good to know - thanks! Looks like I'll be running a ground wire to the GND lug on the alternator this weekend. ::thumb::