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Is that what I think it is around the ground cable off the battery?


*image taken from google

I am not sure where that ground goes, directly to the starter I assume? There is another ground off the battery that does not pass through that coil looking sensor thing. Does GM not trust their output command to the starter, do they need a feedback loop to tell if the starter is running?
 

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Is that what I think it is around the ground cable off the battery?
Yes


I am not sure where that ground goes, directly to the starter I assume?
It goes to a ground point. I'm not sure exactly how the car uses the sensor. I think it's part of checking the charging current. The other wire going to the terminal I think goes direct to the BCM for voltage monitoring. I don't think there's any significant current that goes though that.
 

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Yep commonly called a current transformer, reason it's on the negative is that was the easy way to get all loads except for the smaller other wire on negative, don't matter if + or - is monitored--same current, just easier there, the various modules use this current draw, one is the charging-drop the alternator load scheme another is auto shutdown and I'm sure there is more use of it
 

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The current coil monitors charge as compared to battery voltage. When the battery is charged the Computer lowers the voltage and charge to lessen the alternator load which saves gas and increases battery life. Battery voltage can be monitored on the digital monitor where you can see voltage lowered to a low of 12.3 volts. In older cars without this the alternator output never lets voltage get below 13.7 volts.
 

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Discussion Starter #5
Following up on this post:

I just browsed the Channel list in HP tuners, did not come across anything in regards to current.

Next I looked up the schematic and confirmed the small wire off the negative terminal and of course the [Battery Current Sensor]:
 

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I came across this while researching BAS systems for work:

Not your father’s charging system | Search Autoparts

"The current sensor looks a lot like an inductive amp clamp’s jaws permanently installed around the battery cable. Typically mounted close to the battery, these sensors show up in two versions: stand-alone (SARVC) and non-stand-alone (RVC) models. The stand alone has its own logic functions. Acting in concert with the PCM and BCM via the CAN bus, this current sensor with multiple wires actually controls the field wires connected to the voltage regulator in the alternator."

"The real magic of GM’s RVC as opposed to other PCM-controlled smart charge systems is the use of the current sensor to supplement the “intel” for charging. If the vehicle knows just exactly what the system and the battery needs to be healthy and happy it can work harder when it needs to (slightly over 15 volts) and take it easy when it can. This taking-it-easy approach to charging voltage control allows for lower outputs from the alternator, which of course means the alternator is easier to turn. That spells a fuel economy gain. Even if the gain is very small, add it to several more changes on the vehicle to help with economy and you have some noticeable gains. Besides increasing MPG, the smart charge systems can float back to just over the 12.6-volt mark to maintain battery state of charge, thus increasing the battery’s life. Light bulb life and switch life are increased as well when the voltage levels are slightly lower."
 

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Note that separate wire is to the body control module ground, it is the buss master for most of the car computer run systems, they do not want any spikes coming back to this important module, therefore the separate ground wire
 

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I thought the separate ground was to help it get an accurate reading of the battery voltage (as opposed to the system voltage).
 

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Can I upgrade the negative wire to a one gauge if so do I have to go to that sensor replaced my battery but I'm still getting battery Sensor active light
 

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Can I upgrade the negative wire to a one gauge if so do I have to go to that sensor replaced my battery but I'm still getting battery Sensor active light
I had an issue with my 05 Silverado that also uses that sensor. I made a big3 kit and ran the 1/0 wire outside of the sensor and it caused overcharging issues. Once I ran the wire through the sensor, all was well again. I would suggest you run it through and not risk causing any more voltage issues in your car.
 

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I already did the big 3 upgrade and upgraded the battery I'm thinking the sensor is bad?but you're saying it is OK to upgrade the negative terminal just go through the sensor
 

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I already did the big 3 upgrade and upgraded the battery I'm thinking the sensor is bad?but you're saying it is OK to upgrade the negative terminal just go through the sensor
those sensors aren't known for going bad all too often, but it is possible. Maybe try disconnecting your big 3 and see if that fixes your issue?
 
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