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Discussion Starter #1 (Edited)
Alright fellas, I have some questions about the big 3 and I imagine this question pops up a lot. I can’t find any clear answers to my questions and I have been digging. A lot. I have purchased a 320 Amp Mechman Alternator because I am tired of going 80 mph on the interstate and having my lights dim almost to nothing because of my system. My system isn’t even that powerful but I will probably be adding on so I figured why not.

So my first question is, Where is the engine to chassis ground strap located? I can’t find it on any diagrams or pictures or videos. Can I replace that strap? Or Should I just go from the alternator bracket to a different, new location on the chassis? Because the alternator is basically grounded through the engine correct?

Second series of questions. What wire do I need to thread through the current sensor on the negative side of the battery? Why does not feeding that specific wire through the current sensor trip that battery saver warning? Will 1/0 wire fit through that ring?

I want to do this nicely and neatly considering this is a big investment. So I want to do my research and make sure to do this correctly. I just can’t find the specific answers I’m looking for and I have been DIGGING. Thanks in advance for the responses fellas!

Edit: I guess I should be more specific. The car in question is a 2015 limited lt 3.6L v6.
 

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Alright fellas, I have some questions about the big 3 and I imagine this question pops up a lot. I can’t find any clear answers to my questions and I have been digging. A lot. I have purchased a 320 Amp Mechman Alternator because I am tired of going 80 mph on the interstate and having my lights dim almost to nothing because of my system. My system isn’t even that powerful but I will probably be adding on so I figured why not.

So my first question is, Where is the engine to chassis ground strap located? I can’t find it on any diagrams or pictures or videos. Can I replace that strap? Or Should I just go from the alternator bracket to a different, new location on the chassis? Because the alternator is basically grounded through the engine correct?

Second series of questions. What wire do I need to thread through the current sensor on the negative side of the battery? Why does not feeding that specific wire through the current sensor trip that battery saver warning? Will 1/0 wire fit through that ring?

I want to do this nicely and neatly considering this is a big investment. So I want to do my research and make sure to do this correctly. I just can’t find the specific answers I’m looking for and I have been DIGGING. Thanks in advance for the responses fellas!

Edit: I guess I should be more specific. The car in question is a 2015 limited lt 3.6L v6.
I have an 06 impala ltz which is the 3.9L. So my setup will differ from yours but will be similar. I have a 300amp singer alternator, the mechman is externally regulated so it might make the battery light on your dash stay on. As far as how I ran my wires is something I would recommend (I’m running a 4.5k at a half ohm and have minimal voltage drop). I ran 4 gauge from alt to starter back to battery which is how it was from the factory, I just replaced their “8” gauge with 4. Then a run of 1/0 from alt directly to battery. The current sensor fit 1/0 just fine in my car. You need to have that around the power wire that runs off of the starter. I used to have 1/0 from alt to starter to battery but it’s unnecessary and very difficult to actually get on the starter bolt. Then I have another run of 1/0 from alt to a dual fuse block which has 2 runs to the back battery. There wasn’t a ground to chassis, the ground wire from the engine went straight back to the battery and battery grounds to chassis. I did however add that ground, I put it on the same engine ground location and ran it to the sway/impact bar near the top of the suspension. Obviously is scrapped my grounds. Check out my garage, you’ll kind of be able to see how I have everything setup. And also I have 2 runs of 1/0 to the dual fuse block that runs to the back. Keeps that batteries in parallel and doubles the reserve capacity. Let me know if I can further assist you! Hope this helps
 

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Discussion Starter #3
See my question is, you say that the positive current wire needs to be run through the current sensor, but my current sensor is on the negative side with negative wires running through it. Why do I need to run any positive wire through that current sensor?
Here is my plan for this set-up. I want to leave all factory wiring alone. I want to run a positive wire from the alt to the battery(1/0). Then I want to run a 1/0 wire from the grounding post on the alt to the chassis so that acts like an engine to chassis ground. Then I’ll run another wire from the alt ground post to the battery negative, this wire I plan on running through the current sensor. Then one more wire to the chassis from the negative battery post. I think this plan is pretty good but the only part I’m unsure of is the current sensor.
 

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Discussion Starter #5
That's pretty much how I have it too. I'm thinking I have 2 options. I could solder the stock negative harness to a 1/0 lead and put it to the battery so I just stick the 1/0 through the sensor and I don't really see that being too much of a problem. The other option is to see if I can just wire up another current sensor to the stock wiring in series. That option seems pretty intrusive though. I wouldn't mind either option but I just want to be informed on either decision.
 

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Discussion Starter #6
I suppose I should give an update to this thread. I installed the alternator, and that part went pretty well. Other than the fact that belt accessories are inherently a PITA to work on, it went well. I ended up having to cut off the factory battery post clamp to get the current sensor off (should have just bought a new one and disconnected the old one, but we live and learn. I got hung up on how to connect the factory harness back the battery securely.) If anyone is curious, the alternator comes with a data sheet that tells you exactly what to do with the current sensor. The data sheet says for all 2005 and up GMs (Trucks it said specifically but i assume cars too) should have the current sensor on the ground wire that comes from the alternator ground to the negative battery terminal. I drove the car all over town yesterday with no dimming while driving and the voltage never dropped below 14.2. There is no battery saver message on the DIC. If anyone wants photos just ask and I'll post them in this thread, I need to clean up the wiring still, I left the wires to long Also if anyone has questions about anything that pertains to changing an alt or the big 3 or 4 just ask. I'm happy to help wherever I can.
 

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I have the same 3.9l and am in the beginning stages of the big 3 . I was told to keep all the factory grounds and then add 0/1 from battery to alt bracket and 0/1 from battery to chassis, the 0/1 power wire with 200 amp inline fuse to alt power terminal..id love to see your set up before I get too deep ha .thanks
 
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