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Electrical help! ...again

Cntymnty77

Cntymnty77

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Ok, once I got the truck put back together and drove it around, I noticed the headlights looked really dim. Every mother time I've had this happen, it's been the alternator. The next day I went to O'Reillys and had the battery and alternator tested. The battery was good and it said the alternator was bad. Both were new in April (2017), so I swapped out the alternator with another one.

Now, I still seem to have problems with a low battery (like it's not getting charged). I obviously have electrical issues with this thing and I'm getting them ironed out as I go and I guess this is the next one on the list.

After looking at the wiring diagram for this truck (1983), I've noticed a poss going back to the battery and a poss going to the term block on the firewall. My truck has a single poss going back to the battery and then the poss to the term block coming from the battery terminal. Could this be why my alt keeps going bad/ the battery not getting charged? I also noticed there is a ground on the alt but I don't have a ground wire to connect to it. Would this create the lack of battery charging some how? I don't have any extra accessories on this thing to create a draw while it's not running (as far as I know). I just want to get this fixed, I'm tired of putting it on a charger every night!
 
Grounds are vitally important. Ground from block to battery, frame to block, frame to body. Good words and clean do nections.
 
The housing of the alt is the ground. So when you bolt it to the block it's grounded. Then there should be a ground strap that goes from the engine block to the frame which in turn should go back to the battery.
 
rampage said:
The housing of the alt is the ground. So when you bolt it to the block it's grounded. Then there should be a ground strap that goes from the engine block to the frame which in turn should go back to the battery.
Click to expand...
I figured, I just wanted to make sure I wasn't overlooking something.
 
Use a volt meter - analog or digital - set to DC VOLTS - anywhere over 24 volts should do.*

* Most modern-day digital meters are self-ranging, so you may not have to do that voltage setting for them.

Probe from the NEG (-) battery post to any piece of metal under the hood.

DON'T USE THE OHM METER! You could hit 12 volts and fry the meter innards.

Pay special attention to the engine block, the firewall, the master cylinder, the radiator, the hood (yes, the hood) the inner fender wells, and if you see any voltage showing on your meter.... you have a problem.

From over 50 years experience, I can say that MOST electrical problems are from bad grounds.

Just for giggles, disconnect the negative (-) battery cable (s) and then perform an OHM test on the alternator output lug to the positive side of the battery. You had better see zero Ohms .... or very close to zero Ohms on that circuit!

Why?
Because an OPEN or PARTIALLY OPEN circuit there will damage the alternator fairly quickly. Alternators do not like pushing current into infinite resistance.

They need to be loaded with the battery as resistance and ultimately as the feedback to it's own internal voltage regulator. This is how the regulator works..... it "sees" the load and changes the charging rate to accommodate the battery.

Alternators will not tolerate (for any time - even a moment or two) NOT having the battery load on them at all times.

Now, if everything checks out good, reconnect any disconnected wiring that was disturbed by the previous tests.

With the engine running --- test the alternator output lug, with either meter lead, going to ground with the other meter lead and using your digital* meter's AC test position - read the AC voltage of the alternator output. It must not exceed 0.03 VAC for the alternator to be considered GOOD for use!

* An analog meter may not be able to read this very small AC voltage.,
 
Joe In Montana said:
Use a volt meter - analog or digital - set to DC VOLTS - anywhere over 24 volts should do.*

* Most modern-day digital meters are self-ranging, so you may not have to do that voltage setting for them.

Probe from the NEG (-) battery post to any piece of metal under the hood.

DON'T USE THE OHM METER! You could hit 12 volts and fry the meter innards.

Pay special attention to the engine block, the firewall, the master cylinder, the radiator, the hood (yes, the hood) the inner fender wells, and if you see any voltage showing on your meter.... you have a problem.

From over 50 years experience, I can say that MOST electrical problems are from bad grounds.

Just for giggles, disconnect the negative (-) battery cable (s) and then perform an OHM test on the alternator output lug to the positive side of the battery. You had better see zero Ohms .... or very close to zero Ohms on that circuit!

Why?
Because an OPEN or PARTIALLY OPEN circuit there will damage the alternator fairly quickly. Alternators do not like pushing current into infinite resistance.

They need to be loaded with the battery as resistance and ultimately as the feedback to it's own internal voltage regulator. This is how the regulator works..... it "sees" the load and changes the charging rate to accommodate the battery.

Alternators will not tolerate (for any time - even a moment or two) NOT having the battery load on them at all times.

Now, if everything checks out good, reconnect any disconnected wiring that was disturbed by the previous tests.

With the engine running --- test the alternator output lug, with either meter lead, going to ground with the other meter lead and using your digital* meter's AC test position - read the AC voltage of the alternator output. It must not exceed 0.03 VAC for the alternator to be considered GOOD for use!

* An analog meter may not be able to read this very small AC voltage.,
Click to expand...
Thanks for the help! I guess I need to get a meter. I started looking at it today and I think I'm missing the ground from the block to the frame.

The only ground I see (in the engine compartment) is from the alt bracket to the Neg terminal, the Neg terminal to the core support and then core support to the frame. I don't see anything coming from the block to the frame.

IMG_0081.JPG

IMG_0082.JPG

IMG_0083.JPG
 
Take a picture with the heater hose out of the way. or from a different angle. It looks like the positive has split going to the starter. Can not tell. But something does not look correct. Deffinately missing the frame to block ground. Needs to be a 4 gauge or bigger(smaller number.

While you are in there, change the positive wires out for red. Or at least put red shrink tube on them.
 
Could also get the meter and just measure voltage between the two battery terminals while it's running. If the alternator is charging, it'll read about 14V. If it's not, it'll be closer to 12.
 
There is a braided ground strap from one valve cover bolt to the firewall factory also--if its missing or not connected it can cause weird electrical issues ..some trucks had another ground strap from the transmission pan bolt to the frame also...
 
ktmoutfront said:
Take a picture with the heater hose out of the way. or from a different angle. It looks like the positive has split going to the starter. Can not tell. But something does not look correct. Deffinately missing the frame to block ground. Needs to be a 4 gauge or bigger(smaller number.

While you are in there, change the positive wires out for red. Or at least put red shrink tube on them.
Click to expand...
This is as good as I can get it the way the wiring is on this thing. The positive from the alt, to me, looks a little small.

diesel4me said:
There is a braided ground strap from one valve cover bolt to the firewall factory also--if its missing or not connected it can cause weird electrical issues ..some trucks had another ground strap from the transmission pan bolt to the frame also...
Click to expand...
I looked high and low and couldn't find anything going to the frame, other than the neg from the battery and then splits to the core support.

IMG_0086.JPG

IMG_0087.JPG
 
I see was is going on now. Makes more sense. Add the block to frame wire like has been said. Then see what happens. And by a cheap meter.

Walmart has them for under $20.
 
ktmoutfront said:
I see was is going on now. Makes more sense. Add the block to frame wire like has been said. Then see what happens. And by a cheap meter.

Walmart has them for under $20.
Click to expand...
Thanks for the help! Looks like I need to make a Walmart run. Haha!

Carcinogen said:
While you probably need to add the ground permanently anyway, you can quickly test it with a pair of jumper cables.
Click to expand...
Are you talking about using the cables as a temporary ground from the block and/or alt to frame and then testing it?
 
Jumpers will work nicely!

I never liked that small braided cable to the firewall either.

Most Negative cable replacements I have seen are a #4 or #2 cable plus the #0 or #00 cable that goes to the alternator bracket too. Again, I never liked going to a large sheet metal screw on an alternator bracket for an engine block ground.

I usually try to find a threaded bolt hole on the head and make the ground connection there.

The second, smaller, shorter cable IS INTENDED to go to the inner fender somewhere - depending on Y/M/M and you cannot go wrong with both a frame and a body/fender connection.

Having said that, I've found some serious issues with corrosion at the fender-to-frame ground integrity on older units. Yours may be in that category and it can be fixed either new, bright connections and new ground wires from the battery itself .

HTHAL
 
Wanna have a little Fun?

Pick up your test light and put the spring clamp on the positive/+ battery post.

Then touch the probe to your radiator hose clamps.

Some won't get results.... but many will see something very interesting.

Report back if you DO see an interesting phenomenon.
 
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