2G bad ground???

[wesnaiska23]

i have a feeling there is a bad ground. i used my meter and checked for source voltage at batter and got about 12.4 at the battery(after charging battery). then i left a lead on positive terminal and used a bolt for ground and got source voltage, did te same thing with alternator casing. then i checked it with the alternator relocation bracket and didnt get source voltage. what do you think

 

[weebz1]

it doesn't hurt to check the grounds... it's a cheap fix if that is actually the issue.

Also, did you test the battery with the car on or off? You checked voltage at the alternator? what did you come up with for a value?

Check the voltage at the alternator, then the fuse box, and then the battery..let us know what you come up with.

 

[wesnaiska23]

first i tested with car off
got 11 volts at battery
because car was running and alt wasnt charging the battery. i checked the power cable and still finding source voltage.
now when i started the car i tested the battery and it was at 12v.
now i tried something and i dont know if this will mess anything up but i took a 6guage cable and grounded the body of the alternator to the negative battery post and i noticed that the voltage shot up to almost 14v. so what do i do now?

i am kinda nervous of doing that again. would that be able to fry me ecu? cause there was spark

 

[weebz1]

Check the grounds thoroughly not just visually, just because they look okay doesn't mean they are connecting right. make sure your negative terminal is tight and free of corrosion. same with the grounds.

Also, what was the main issue you were having that made you feel you should check this out? lights dimming orrr what's the MAIN issue here other than your not getting the correct voltage

 

[steve]

If your using an alternator relocation bracket you should check the resistance between the alternator casing and the battery negative terminal. You should do this with the car off and read very close to 0 ohms resistance.

Given the results you have so far it wouldn't surprise me if you got the same result with a ground strap between the alternator case and the engine block but if you don't you'll know to look at the engine grounding.

When initially charging the battery you're going to see around 14v on the electrical system if the alternator is working.

 

[weebz1]

^ didn't even see that he had the relocation bracket..

 

[wesnaiska23]

i will check this later today and let you guys know the results

 

[zeirocool]

Your battery should be at 12.6 volts your alternator output should be 14.4 volts

 

[wesnaiska23]

i checked continuity negative battery post to alternator casing it was 0. and i checked negative post to engine block and no continuity

 

[steve]

Don't see how it's possible for you have have continuity between the alternator casing and the negative terminal but not to the engine block from the terminal. The started also depends on the engine block (at least the transmission casing) having a solid ground.

 

[boost97gst]

It wouldnt start if that were true. Retest. You got a bad connection on the block. Check it at the starter bolt. And dig the probe in, theres alot of grease everywhere and dirt.

 

[wesnaiska23]

i was so confused by that also. ummm does the alternator have
to be grounded to the block or can i just take a 5 or larger guage wire and ground that to the chassis?
if i cant do that then i think i will take everything apart and sand down the block a little then put the relocation bracket back
on

 

[psx]

Get some sand paper and clean all the grounds related to charging/starting. It takes like 15 minutes it might help you.

 

[steve]

does the alternator have to be grounded to the block or can i just take a 5 or larger gauge wire and ground that to the chassis?

You just need good grounds. How you do it is flexible.

The alternator is just one of the critical ones because of the amount of current that flows just like the battery but the engine needs a good ground too since the starter, some sensors, and ignition require a ground to work.

The chassis ground is made by the cable from the battery to the firewall. That connection depends on the threads of the bolt in the firewall being clean unless you expose some clean metal on the firewall.

The engine block ground is from the transmission mounting bolt to the battery. The bellhousing, bolt head and threads, and cable terminals need to be clean.

There is another engine ground via the strap from the intake manifold to the firewall, to make sure the head, IM, and TB are grounded.

The alternator normally grounds via the mounting bracket to the block. Giving it a ground back to the battery will improve the path.

 

[wesnaiska23]

You just need good grounds. How you do it is flexible.

The alternator is just one of the critical ones because of the amount of current that flows just like the battery but the engine needs a good ground too since the starter, some sensors, and ignition require a ground to work.

The chassis ground is made by the cable from the battery to the firewall. That connection depends on the threads of the bolt in the firewall being clean unless you expose some clean metal on the firewall.

The engine block ground is from the transmission mounting bolt to the battery. The bellhousing, bolt head and threads, and cable terminals need to be clean.

There is another engine ground via the strap from the intake manifold to the firewall, to make sure the head, IM, and TB are grounded.

The alternator normally grounds via the mounting bracket to the block. Giving it a ground back to the battery will improve the path.

i found a good ground that had 0mv resistance. i took a 5guage wire and grounded the alternator to the new ground i found. i jump started the car because the battery was extremely low before. i measured the voltage at the battery while car was running and the voltage was at about 13v but it was consistent. if i put a fully charged battery will it be at the 14v that its suppose to be?

 

[steve]

The voltage will vary depending on how much current is required and the temp of the alternator so I wouldn't worry about the voltage right now.

A fully charged battery is less load on the alternator so the voltage might rise if the alternator was not able to provide enough current right now (like a really dead battery)

I do want to point out that a reading of 0 mv is a voltage measurement and meaningless in the context of measuring resistance where the units are ohms. This might have been a typo or an indication that you weren't actually measuring resistance which would make the conclusions invalid.

If you're not sure how to use your meter, post a picture of it.

 

[wesnaiska23]

sorry thats what i meant. i set it to ohms and setup the meter to beep when theres a good ground from negative post to my other ground

 

[steve]

Cool. The beepers on a lot of meters will go off when when there is some resistance in the link but if your reading 0 ohms between that point and the negative battery terminal it sounds like a good ground connection.

 

[wesnaiska23]

imma put in a new battery and see how everything works out. thanks for the help