Car dies from electrical issue

[justin0469]

Ever since I have had the car, I have had problems with voltage levels and the alternator. At idle it is common to be well below 12v and never about 13.8v while driving (even after new alternator), and thats not even all the time. The only time it will go above 12.5v at idle is when I start it for the first time after it has been sitting all night. Today in the McD's drive thru, out of no where, my car just dies like there is no electrical power at all. I open the hood and jiggle around the wires coming off the battery. I heard relays click and I get back in the car and it is fine now.

Is there specific wires that I should replace and tighten down, or just all of them coming off the battery?

 

[luv2rallye]

Remove, clean with wire brush and sandpaper, and retighten all cable ends going to/from battery (both ends of each cable and what they attach to including battery posts, terminals, and body ground connection). Also big one on alternator (remove battery positive cable before doing this). Also negative cable end that goes to starter casing bolt. Bend big cables to make sure they are not stiff and brittle. Then measure voltage right on the big alternator terminal when car is running and on the battery + terminal. They should be the same or you have a bad cable. In fact measure this before you clean anything so you have a reference.

 

[95blackGsTurbo]

You should never go below 12V at anytime with the car running. I could be at a stoplight with the stereo, AC and headlights on and still have 13.2V at idle. Good idea to check voltage at both places. You can also check resistance in the wire. That will tell you if it is corroded.

 

[justin0469]

Isn't the negative cable for the starter a flat blade connector? Would it hurt to just run all new wires from the battery?

 

[luv2rallye]

Yes. No - that's fine (especially if they are old). Measuring resistance requires a meter that can read 0.01 ohms which most people don't have. You also have to disconnect one cable end which may have just affected your problem and give missleading results. It's easier to just see if there is any voltage drop across the cable (end to end) when current is passing through it (example: when lights on, starter engaged, etc). If you measure any, the cable is bad (has resistance) and needs to be replaced (or terminals need cleaning).

 

[justin0469]

When looking for new connectors for the + and - on the starter and alternator, is pretty much any terminal for a 4 AWG going to be big enough to stick a bolt through or do I need to be looking for a specific size hole?

 

[jott5555]

you cold get one of those sweet grounding kits on e-bay.. but basically clean all your ground's and grounding points your car will be much happier

 

[justin0469]

Anyone know a good way to ground the starter with larger gauge wire since it uses a flat blade connection? happen to know if your average female flat blade will fit on the male side on the starter if you just used the same gauge wire?

 

[grnchevyz]

Car running you should see 13.8v to 14.4v. If you see below this on a new alternator, I'd start with the ground wires as mentioned before. Changing them is a good idea but not necessarily requried.

There should be 2 ground wires on the battery from the factory, one about 10" that goes directly to the firewall and another about 24" or so that goes to the block. Make sure there is no corrosion on either end of the connector and that everything is clean/tight.

Once this is confirmed, check voltage again.

If the same result happens, replace wire that goes to the alternator with either an 8g or 4g wire directly from the + side of the battery.

If problem goes away, then the issue is loss of voltage between the battery to starter to alternator link.

You can leave it that way and call it a day, or replace the wire to the alternator - starter, check again and replace the wire from alternator - battery and check again.

Hope this helps...I had this issue on a client's car and replacing the alternator wire to go directly to the battery solved it.

 

[justin0469]

So there is a positive wire going from battery to alternator, battery to starter, and a negative from battery to firewall and battery to block and thats it? Where does the negative from the starter and alternator go from the factory? They are grounded to the body some where?

 

[justin0469]

Is it better to use the factory 80A fuse for the alternator or get a new inline one? I am not sure if a 4AWG wire will fit the factory fuse box.

 

[grnchevyz]

When I change wiring the way I do it is the following:

4 gauge from Battery Positive to Starter
4 gauge from Battery Positive to Alternator
8 gauge from Battery Positive to Fuse Box

4 gauge from Battery Negative to Ground distribution block that is grounded to Frame
8 gauge from distribution block to block
8 gauge from distribution block to alternator
8 gauge from distribution block to tranny
8 gauge from distribution block to head or valve cover
8 gauge from distribution block to throttle body


As for the fuses, keep the factory ones there...they are there for a reason.

hope this clarifies it!

 

[justin0469]

Is it really necessary to ground all that? Didn't you forget the starter?

I haven't had the chance to really look at my under hood fuse box, but where does that B+ go to the box? Also, since there is an alternator fuse, shouldn't that mean that the positive should go from the battery to the fuse to the alternator? "They are there for a reason," right? I just suggested that the wire just have an inline fuse for simplicity.

The alternator I have is 135A. Should I get a larger then stock ampere fuse?

 

[luv2rallye]

I haven't had the chance to really look at my under hood fuse box, but where does that B+ go to the box? Also, since there is an alternator fuse, shouldn't that mean that the positive should go from the battery to the fuse to the alternator? "They are there for a reason," right? I just suggested that the wire just have an inline fuse for simplicity.

The alternator I have is 135A. Should I get a larger then stock ampere fuse?

Battery + (two 10ga white wires) goes to the front side of the large 2nd from the left fuse which should be 100A (not 80). It also (another two 10ga white wires) goes to a different bus bar in the fusebox.

Yes the alt should have a fuse (in case of short). The 100A fuse serves this purpose and supplies a couple other fuses also.

You never use a larger than stock fuse unless ALL the relevant wires downwind are increased in size to handle it (or individually fused at what they can handle).

 

[justin0469]

Will 4ga wire fit into the fuse box where 10ga wire was previously? There are two wires that go to the front of each fuse, but I could replace them with 1 4ga wire?

Yes the alt should have a fuse (in case of short). The 100A fuse serves this purpose and supplies a couple other fuses also.

So then I shouldn't make a wire from the B+ to the alternator + with an inline fuse or not since this 100A fuse is the line going to the alternator? Or should I just forget the fuse box connections and run a new wire to the alternator with an inline fuse, and since that is the only connection on that wire, it can be a 135A fuse?

To put the project all together, is this how it should be:
New wire from B+ to alternator + with 135A inline fuse
New wire from B+ to starter + with ??A inline fuse
2 new wires to the B+ connections on the fuse box

New wire from B- to frame
New wire from B- to block
New wire from alternator - to good ground.

I'm just trying to sort out all the different information I am reading.

 

[justin0469]

Any one know what ampere fuse the starter would need?

 

[grnchevyz]

Any one know what ampere fuse the starter would need?

Depending on the draw of your alternator I'd go 150 - 200 on the in-line.

The more grounding points the better...the ground off the alternator is already there so no need to change it...

Never had an issue with the gorunds I mentioned and I definitely see a little more response out of the engine and the car overall.

Hope i've been helpful

 

[justin0469]

If its a 135A alternator, I think I'm going to go with 120A inline fuse. Part of the point of this project is replacing wires that aren't good enough because they are old and crappy, including the grounds.

Can anyone comment on my plans?

New wire from B+ to alternator + with 120A inline fuse
New wire from B+ to starter + with _____A inline fuse
2 new wires to the B+ connections on the fuse box

New wire from B- to frame
New wire from B- to block
New wire from alternator - to good ground.

 

[luv2rallye]

B+ to starter has a magnetic switch (starter solenoid) on the starter and should not have an inline fuse. The reason is because it may draw hundreds of amps for the first millisecond (since windings are almost a short circuit for the first ms.). After a ms it settles down to 50-90 amps. So any fuse you put in will probably blow sometime and a way too large one defeats the reason for having it since the car may burn down before it blows. The magnetic switch is the only thing that should be in that circuit. You can put larger wire there if you want.
The alternator ground is through it's bracket to the engine block so unless you have a very bad connection there, no wire is needed (a large block to B- will suffice).

 

[justin0469]

Well, right now there is a ground wire coming off the alternator. I suppose I am assuming it is a ground wire but it does disappear into a wire harness. Is there just two lines coming off of the B- ; one to frame, one to the block?

So you are saying I can just run a new wire from B+ to starter

And since the two white 10gauge wires that go to the fuse box attach at different places (correct?) for power that is seperate from the alternator fuse, I couldn't replace them with a single 4 gauge wire and would be overkill to use two 4 gauge wires, so I should just leave them after making sure they are good wires?

 

[luv2rallye]

Well, right now there is a ground wire coming off the alternator. I suppose I am assuming it is a ground wire but it does disappear into a wire harness.

How do you know it's a ground wire? Did someone connect to the alt casing or mounting bolt? The stock alt has two 10ga white wires on the big post (which you can replace with one 4ga if you want which handles more current) and a 4 wire connector on the front. I don't know what a non-stock alt has.

Is there just two lines coming off of the B- ; one to frame, one to the block?

Yes.

So you are saying I can just run a new wire from B+ to starter

Yes.

And since the two white 10gauge wires that go to the fuse box attach at different places (correct?) for power that is seperate from the alternator fuse, I couldn't replace them with a single 4 gauge wire and would be overkill to use two 4 gauge wires, so I should just leave them after making sure they are good wires?

I would just leave them but you can replace each pair with a 4ga if it bothers you (four 10ga wires carry more current than one 4ga which is why you can't have only one 4ga). Remember the biggest current by far flows to the starter and from the alt. (unless you have some 1000W stereo but that would have to have it's own wiring to the battery).

 

[justin0469]

How do you know it's a ground wire? Did someone connect to the alt casing or mounting bolt? The stock alt has two 10ga white wires on the big post (which you can replace with one 4ga if you want which handles more current) and a 4 wire connector on the front. I don't know what a non-stock alt has.

I was just assuming. But it was on the stock alternator when I took it off. I can take a pic of it when I do my oil change later. I know the B+ is at the top of the alternator and is covered by a cap and the connector is in the front of the alternator, it is not either of those.

 

[grnchevyz]

I was just assuming. But it was on the stock alternator when I took it off. I can take a pic of it when I do my oil change later. I know the B+ is at the top of the alternator and is covered by a cap and the connector is in the front of the alternator, it is not either of those.

NEVER assume something like that. ALWAYA check wires for polarity if you are unsure. Any hardware store will have a 12v trouble light. Stick the clamp on B+ and probe that wire, if the light goes on, then it's a ground, otherwise, it's power (obviously ).

So you are saying I can just run a new wire from B+ to starter

Yes run a 4ga wire from B+ to Starter +. Also run one from B+ to Alternator +. It will ensure a good connection and allow for more power to run through without melting wires.

As far as the wires going to the fuse box, you can also replace them but they are fine jsut the way they are. The important ones are the ones coming from B+.

And yes, ground as many points as you possible can. 4 or 5 is perfect as I mentioned before.

Good Luck and let me know if you need more help.

 

[justin0469]

NEVER assume something like that. ALWAYA check wires for polarity if you are unsure. Any hardware store will have a 12v trouble light. Stick the clamp on B+ and probe that wire, if the light goes on, then it's a ground, otherwise, it's power (obviously ).

I suppose you are correct but since I knew there were no positive wires in the area other than the one that was already connected to the alternator, and this wire was already hooked up to the old alternator, if it was a positive wire, the old alternator would have blown up.

 

[justin0469]

Here are the pics of the alternator and where the wire was. If its not for grounding, what is it for? It's just a bolt on the case, it doesn't go into the alternator.