Bad ground strap to alternator

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TX87R10

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I have been tracking down an electrical gremlin this weekend and I found when checking with my multimeter that touching the ground strap on the alternator it is good but when I touch the block or alternator it is not connected or smth. I get the beep only on the block not frame or anything

All lights work but when I try to turn it over I get a single click and then lights die. I was pretty sure it was going to be a ground issue.

Anyway I checked the alternator and the bolt the ground connects to seems to be freely spinning. Going to see if I can fix that but wanted to ask - would it make sense to just add another ground strap either way to the block? If so what is the best place? I am not an electrician just a weekend diy car guy
 
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TX87R10 said:
I have been tracking down an electrical gremlin this weekend and I found when checking with my multimeter that touching the ground strap on the alternator it is good but when I touch the block or alternator it is not connected or smth. I get the beep only on the block not frame or anything

All lights work but when I try to turn it over I get a single click and then lights die. I was pretty sure it was going to be a ground issue.

Anyway I checked the alternator and the bolt the ground connects to seems to be freely spinning. Going to see if I can fix that but wanted to ask - would it make sense to just add another ground strap either way to the block? If so what is the best place? I am not an electrician just a weekend diy car guy
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Your alternator ground has nothing to do with the condition you are describing. You could have something as simple as dirty battery cable connections or a bad battery. I would charge the battery and clean the battery cable connections 1st. If you've already done that or after you do that post back,we can help you trouble shoot further. You can add a ground strap any where you want on that alternator assuming it's factory. The whole case is a ground the bolt that tightens it to the adjustment bracket has always been a good enough ground for me. Take a pic of what you are dealing with. If your B+ post is spinning you probably aren't charging the battery.
 
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What makes you think it’s unrelated? I’m getting 12v to the starter s post I checked with multimeter

Battery is at auto zone charging now to be sure but I had it tested the other day and it’s good. I’ll clean the cables again to be sure
 
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TX87R10 said:
What makes you think it’s unrelated? I’m getting 12v to the starter s post I checked with multimeter
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You can take the alternator off the car and it will still start. Just because you have 12v doesn't mean you have a good enough connection to carry the amperage needed to start the car.
 
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Ricko1966 said:
You can take the alternator off the car and it will still start. Next question? Just because you havec12v doesn't mean you have a good enough connection to carry the amperage needed to start the car.
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I’ll have to try that actually, I figured if you had no ground to the block the starter wouldn’t get power in that scenario
 
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TX87R10 said:
I’ll have to try that actually, I figured if you had no ground to the block the alternator wouldn’t get power in that scenario
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The alternator just charges the battery. The battery,cables,starter and starter wires start the car.
 
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Ricko1966 said:
The alternator just charges the battery. The battery,cables,starter and starter wires start the car.
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You were able to quote me before I fixed that, the starter not the alternator.
 
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Ricko1966 said:
The alternator just charges the battery. The battery,cables,starter and starter wires start the car.
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Just to be clear you are saying that even if there is no ground to the block via the alternator and hence none to the starter that it can still start? I am going to pick up the battery in a few will test that out first.

That definitely contradicts a lot of what I’ve read in this forum so just wanted to be sure
 
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Okay so the ground from the battery to the alternator BRACKET is bad. Okay yes that could cause your problem. You can relocate that ground probably easiest is just use a nut and a bolt or a larger diameter self tapper to fix what you have. Pics are a big help. You need to be sure you have a ground cable from the battery to the body,usually the radiator support a ground to the block and a ground to the frame. Probably simplest would be buy a new ground cable with 2 leads a big one and a small one,also a cable with 3 eyelets 6 gauge. Runnthe big lead to any good mounting point on the block,attach one end of the 2 eye cable there also,connect the other eye to a clean solid spot on the frame. Connect the small cable from battery negative to the radiator support.
 
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Red arrow that nut seated on the alternator housing free spins. Checking continuity here is good though.

Blue arrow checking continuity no good
You must be registered for see images attach



That **** is hard to do on a phone lol
 
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TX87R10 said:
Red arrow that nut seated on the alternator housing free spins. Checking continuity here is good though.

Blue arrow checking continuity no good
You must be registered for see images attach



That **** is hard to do on a phone lol
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That is your alternator B+ post. Your alternator more than likely is not charging your battery.Best advice is replace the alternator. This is why pics are important everybody.
 
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Ricko1966 said:
That is your positive post. Your alternator more than likely is not charging your battery.Best advice is replace the alternator.
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Not sure if you saw my original post but the battery wasn’t dead headlamps everything working good only seems to “die” when engaging the ignition. Condition only exists when engaging the ignition and lights come back right after releasing it. Tested with a multimeter and there is 100% an issue with continuity only to the block, which the starter gets its ground from. I’m going to take the alternator out of the equation completely by grounding the block elsewhere to verify but was looking for a good place to do so

Battery died last night bc I got frustrated and left the keys in it after testing the power to the starter again.
 
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TX87R10 said:
Not sure if you saw my original post but the battery wasn’t dead headlamps everything working good only seems to “die” when engaging the ignition. Condition only exists when engaging the ignition and lights come back right after releasing it. Tested with a multimeter and there is 100% an issue with continuity only to the block, which the starter gets its ground from. I’m going to take the alternator out of the equation completely by grounding the block elsewhere to verify but was looking for a good place to do so

Battery died last night bc I got frustrated and left the keys in it after testing the power to the starter again.
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The connection in your picture,is not a ground. And the alternator is not keeping your truck from starting. Take a jumper cable hook it to negative battery cable and clamp it on an intake bolt,fuel pump bolt,something attached to the block. Now try to start it. No start still, it isn't your ground. It starts rework your grounds like my previous post. I suspect your battery isn't charging because of the alternator B+ post the battery still has enough juice to turn on the very small amp draw lights,but not enough juice to turn the giant amp draw starter.
 
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Look at your pic in number 10 the red is not a ground the blue is the alternator case which is supposed to be grounded.
 

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Battery can have enough juice to turn on lights, etc, but not have enough amps to turn over the engine. Bad battery is possible, bad connections are possible, bad grounds also possible.
 
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