Big 3 upgrade question?

[Brandon2489]

So I have been looking into doing a big 3 upgrade for awhile but it seems all the videos or tutorial I see have a different setup. It's not that I need a tutorial but more of an observation. Most other Tahoe's I have seen this done to are from 2007-2009. They have the 175 amp fuse located on the firewall. Mine is in the positive battery post. It also seems nobody takes into account the battery current sensor and running the added ground through this. I have only seen one video and one tech tip from mechmanalternators.com. In Mechmans tech tip they only have one wire going through the sensor( negative terminal to forward right of engine block) and not the small ground wire from negative terminal to frame. Also what about the ground strap from the firewall to the aft left of the engine block. Most don't talk about this either. So what's the right configuration supposed to be? I have attached pics of my current factory setup. I will say the big ground strap going through the sensor currently is actually of decent size.

 

[iamdub]

You're overthinking it. Let's simplify it:

First off, the system is only as strong as its weakest (smallest) link. So, even if that ground appears to be "of decent size", it could still be improved and MUST be improved if you upgrade the other wires. Otherwise, they're all a waste.

The point of the Big 3 is to improve the positive connection between the alternator and battery, the negative connection between the battery and frame and the negative connection between the engine block and frame. The engine block is used to complete electrical circuits, primarily the starter, which is the largest load your battery will see. This is why the block-to-frame ground is included in the 3. That relatively small braided one from the engine block to the firewall is to ground the body/sheetmetal, as the smaller electronics are grounded to the body all throughout the vehicle.

I forget the size, but I think it's 0 gauge or 1/0 that will fit through that RVC sensor. It might be a snug fit, but a fit nonetheless.

I left all the factory grounds in place and just added the Big 3 cables. I completely replaced the alternator charge cable with the larger cable. My engine-to-frame ground is on the driver side. It's a really short run from under an engine mount bolt to the boss that the brace for the power steering pump screws in to. I left that factory ground to the passenger cylinder head. I also left the factory ground going through the RVC sensor.

I'm not familiar with your positive battery connection setup. Is yours a PPV or do you have the dual batteries?

Does that large positive cable connected to the 175A fuse go to the alternator and fuse/relay center, etc. and the red one goes to the starter? If so, you'd upgrade the one going to the alternator.

I upgraded my starter cable just 'cuz.

Mine: https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1567413 and https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1567416 and, finally https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1570382

 

[Doubeleive]

I increased the cable size from alternator to battery as dub noted above, I have a dual battery system so I connected both battery grounds together at the main battery terminal and added a ground from the alternator mounting bracket to the frame. This way I didin't have to run 2 cables thru the sensor or a larger one, I am assuming the sensor can still pick up the load from the one cable since they are married at the terminal.

 

[Brandon2489]

You're overthinking it. Let's simplify it:

First off, the system is only as strong as its weakest (smallest) link. So, even if that ground appears to be "of decent size", it could still be improved and MUST be improved if you upgrade the other wires. Otherwise, they're all a waste.

The point of the Big 3 is to improve the positive connection between the alternator and battery, the negative connection between the battery and frame and the negative connection between the engine block and frame. The engine block is used to complete electrical circuits, primarily the starter, which is the largest load your battery will see. This is why the block-to-frame ground is included in the 3. That relatively small braided one from the engine block to the firewall is to ground the body/sheetmetal, as the smaller electronics are grounded to the body all throughout the vehicle.

I forget the size, but I think it's 0 gauge or 1/0 that will fit through that RVC sensor. It might be a snug fit, but a fit nonetheless.

I left all the factory grounds in place and just added the Big 3 cables. I completely replaced the alternator charge cable with the larger cable. My engine-to-frame ground is on the driver side. It's a really short run from under an engine mount bolt to the boss that the brace for the power steering pump screws in to. I left that factory ground to the passenger cylinder head. I also left the factory ground going through the RVC sensor.

I'm not familiar with your positive battery connection setup. Is yours a PPV or do you have the dual batteries?

Does that large positive cable connected to the 175A fuse go to the alternator and fuse/relay center, etc. and the red one goes to the starter? If so, you'd upgrade the one going to the alternator.

I upgraded my starter cable just 'cuz.

Mine: https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1567413 and https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1567416 and, finally https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1570382

Ok so to recap.

You left all factory wiring/grounds.

1. Added 1/0 ground wire from negative terminal then through RVC then to under strut mount bolt.

2. Added 1/0 ground from forward left side of block to frame under engine mount bolt.

3. Replaced positive wire from battery to alternator with 1/0 wire.

Yes you are correct that fusible link has 3 wires coming from it. One to the fuse/relay box. One to starter and one to the alternator. I do not have a PPV or dual battery setup. That is why I was kind of confused on the this setup because the fusible link location was different. I'm guessing GM had gone to this design on the Tahoe around 2010. It doesn't even have the studs to mount the fusible link on the firewall anymore.

 

[iamdub]

Ok so to recap.

You left all factory wiring/grounds.

1. Added 1/0 ground wire from negative terminal then through RVC then to under strut mount bolt.

2. Added 1/0 ground from forward left side of block to frame under engine mount bolt.

3. Replaced positive wire from battery to alternator with 1/0 wire.

Yes you are correct that fusible link has 3 wires coming from it. One to the fuse/relay box. One to starter and one to the alternator. I do not have a PPV or dual battery setup. That is why I was kind of confused on the this setup because the fusible link location was different. I'm guessing GM had gone to this design on the Tahoe around 2010. It doesn't even have the studs to mount the fusible link on the firewall anymore.

Left all factory wiring/grounds.

1. Added 1/0 from negative to under strut mount bolt. The factory ground is still going through the RVC sensor. Actually, I think there are two grounds going through it, but, anyway.

2. Correct. It was short and easy to access since that side of the engine only has a steering shaft versus the right side that has battery wiring and A/C lines

3. Correct.


I've never paid attention to that being a difference in the 2010+. Regardless, you do the Big 3 just the same. Actually, with your setup, you would only need three wires to do the basic Big 3. Mine needed four since the alternator was connected to the fuse on the firewall, then I needed to go from the other end of the fuse to the positive battery terminal. It's still three legs of connections, just one is broken up by that fuse. Since you have a stud on the "outlet" side of the fuse, you can land your alternator-to-battery cable there. I'm sure that the one that's molded into the battery terminal is the starter cable. You can leave this as-is, but, if you wanna upsize the starter wire, you'd have to get a different battery terminal, like the one I used.

 

[Brandon2489]

Left all factory wiring/grounds.

1. Added 1/0 from negative to under strut mount bolt. The factory ground is still going through the RVC sensor. Actually, I think there are two grounds going through it, but, anyway.

2. Correct. It was short and easy to access since that side of the engine only has a steering shaft versus the right side that has battery wiring and A/C lines

3. Correct.


I've never paid attention to that being a difference in the 2010+. Regardless, you do the Big 3 just the same. Actually, with your setup, you would only need three wires to do the basic Big 3. Mine needed four since the alternator was connected to the fuse on the firewall, then I needed to go from the other end of the fuse to the positive battery terminal. It's still three legs of connections, just one is broken up by that fuse. Since you have a stud on the "outlet" side of the fuse, you can land your alternator-to-battery cable there. I'm sure that the one that's molded into the battery terminal is the starter cable. You can leave this as-is, but, if you wanna upsize the starter wire, you'd have to get a different battery terminal, like the one I used.

So did you not put that added ground through the RVC sensor? Reason I ask is I was under the impression that if you add any extra grounds from the negative terminal and it doesn't go through the RVC then it can cause issues. Let's say if the 2 factory ground cables or one for that matter going through the RVC failed. It would give a battery charge message on the display. But since there is an added ground not going through the sensor the system is technically operating normal since it has the added ground. If this were to happen it would cause some trouble shooting issues. It would also not be able to regulate the voltage correctly since it's not going through the sensor. Just so we are clear I'm not saying you are wrong at all. I'm just trying to wrap my head around the RVC system and this is the way I understand how it works. Although in a nutshell lol Thanks again for your help. and yes I am probably still overthinking it haha.

 

[jeremiahm]

This is what I did taking into account the sensor:

Charging system upgrade

Hello all, first post, thanks for all the help! I have a 2007 Yukon Denali XL with every known issue accept the DoD stuff, just discovered I am one of the chosen with a smooth engine valley cover and no DoD on my 6.2! Been having issues with what feels like stutters, but no codes thrown...

www.tahoeyukonforum.com

Jeremiah

 

[iamdub]

So did you not put that added ground through the RVC sensor? Reason I ask is I was under the impression that if you add any extra grounds from the negative terminal and it doesn't go through the RVC then it can cause issues. Let's say if the 2 factory ground cables or one for that matter going through the RVC failed. It would give a battery charge message on the display. But since there is an added ground not going through the sensor the system is technically operating normal since it has the added ground. If this were to happen it would cause some trouble shooting issues. It would also not be able to regulate the voltage correctly since it's not going through the sensor. Just so we are clear I'm not saying you are wrong at all. I'm just trying to wrap my head around the RVC system and this is the way I understand how it works. Although in a nutshell lol Thanks again for your help. and yes I am probably still overthinking it haha.

Actually, I applaud you for your forethought and trying to fully understand something rather than just "modding away". People doing mods seemingly just to lengthen their mod list are how manufacturers of throttle body spacers, "the Tornado", the cheap "cold" air intakes, etc. stay in business. A self-thinker is a refreshing find, so thank you.


Electricity takes the best (most conductive) path. The sensor is there to read the current flowing through the system. Having a much bigger (more conductive) path around (literally!) that sensor will drastically reduce the amount of current traveling along those factory grounds going through the sensor. So, you are correct in the RVC system not accurately reading and, therefore, compensating for the loads.

I'm aware of this but haven't even bothered enough to watch my voltage gauge to see if the RVC is cycling as often or as much as it used to. I don't even remember if I had tried to route that big wire through the sensor. I actually like the concept and function of RVC, so I'm gonna make it a point to revisit my setup when I reclaim my Tahoe.

If my 1/0 wire fits through the sensor, I'll route it there and use the original main ground wire to upgrade the engine/frame-to-body circuit. The smaller factory ground (that I think is for the core support/headlights) will just be routed to the frame or something where it'll function just the same. This will make all of the electrical system monitored by the RVC, restoring factory operation. It'll also clean up the wiring on top of the battery.

 

[Brandon2489]

Actually, I applaud you for your forethought and trying to fully understand something rather than just "modding away". People doing mods seemingly just to lengthen their mod list are how manufacturers of throttle body spacers, "the Tornado", the cheap "cold" air intakes, etc. stay in business. A self-thinker is a refreshing find, so thank you.


Electricity takes the best (most conductive) path. The sensor is there to read the current flowing through the system. Having a much bigger (more conductive) path around (literally!) that sensor will drastically reduce the amount of current traveling along those factory grounds going through the sensor. So, you are correct in the RVC system not accurately reading and, therefore, compensating for the loads.

I'm aware of this but haven't even bothered enough to watch my voltage gauge to see if the RVC is cycling as often or as much as it used to. I don't even remember if I had tried to route that big wire through the sensor. I actually like the concept and function of RVC, so I'm gonna make it a point to revisit my setup when I reclaim my Tahoe.

If my 1/0 wire fits through the sensor, I'll route it there and use the original main ground wire to upgrade the engine/frame-to-body circuit. The smaller factory ground (that I think is for the core support/headlights) will just be routed to the frame or something where it'll function just the same. This will make all of the electrical system monitored by the RVC, restoring factory operation. It'll also clean up the wiring on top of the battery.

Thanks for understanding and taking the time to explain. As you said as well my goal is to have all the electrical system monitored by the RVC and function as factory. I have no doubt people have done the big 3 and have had success but I can't help think that some have induced electric issues like a ground loop while doing this mod by placing ground straps wherever they see fit. So instead of adding any extra wiring I think what I will do is just keep all factory ground locations and just replace factory ground wires from negative terminal with bigger 0/1 and maybe 4 gauge for the headlight harness ground wire(the smaller cable going through the RVC) and replace the battery positive terminal wire to alternator since they all seem to be working for the most part other than headlights dim for a split second when fans kick on. Reason for this thread and another one which by the way I will start off with a new battery as someone suggested and go from there. Thanks again for the insight.

 

[Doubeleive]

So did you not put that added ground through the RVC sensor? Reason I ask is I was under the impression that if you add any extra grounds from the negative terminal and it doesn't go through the RVC then it can cause issues. Let's say if the 2 factory ground cables or one for that matter going through the RVC failed. It would give a battery charge message on the display. But since there is an added ground not going through the sensor the system is technically operating normal since it has the added ground. If this were to happen it would cause some trouble shooting issues. It would also not be able to regulate the voltage correctly since it's not going through the sensor. Just so we are clear I'm not saying you are wrong at all. I'm just trying to wrap my head around the RVC system and this is the way I understand how it works. Although in a nutshell lol Thanks again for your help. and yes I am probably still overthinking it haha.

The rvc sensor is just there to prevent over charging/fuel economy, if you unplug it there are no dash errors or lights, also if you had 2 wires going thru it and one broke it wouldn't alert you, if the alternator failed and it was not charging that has nothing to do with the rvc sensor. If the one existing ground failed it also would (probably) not alert you, the vehicle would simply not start