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Discussion Starter #1
Ok, I know this isn't diesel related but I hope someone here may be able to answer my question

Traded off our 2011 Tahoe for a 2016. I think I may have made a mistake. The owners manual says to disconnect the negative battery cable after getting it ready to tow. Is the only reason to disconnect the negative battery cable to make sure the steering stays unlocked or is there some other reason? The '11 didn't have the locking steering so all we had to do is put the transfer case in neutral and go. Didn't have to pull fuses or anything. Most states require auxiliary brakes and breakaway brakes on tows more than 3000 lbs. You can't have either if the battery is disconnected. If the only reason is to keep the steering unlocked, I can disable the lock on the column. Any one know for sure why the battery must be disconnected.
 

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Discussion Starter #2
Hmmm, this is the same response I get from GM.
 

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https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.gmc.com/content/dam/GMC/global/master/nscwebsite/en/home/Experience_GMC/Trailering_and_Towing/Towing/01_images/TT-Release.pdf&ved=0ahUKEwjAqKPwicjKAhXFFz4KHebqDkcQFggbMAA&usg=AFQjCNFvcI-ot_m6emqLojT54nIQDbn6MQ&sig2=rVjIXpYIeZg4klWlU4AQuw

You will damage the steering column with the battery connected (and not following the sequence). As for brakes, there are actuators for that. I see no reason that a disconnected battery will prevent braking.
 

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Discussion Starter #4
If the only reason to disconnect the battery is because of the steering lock, I had the dealer disable that. As for braking, in the case of a breakaway, the aux. braking system uses the towed vehicles 12v source to activate since it is no longer connected to the tow vehicle.
Someone said it would damage sensors and modules. But if you dolly tow the vehicle, the books doesn't say you have to disconnect the cable. Wouldn't the same sensors and modules be affected?
 

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Couldn't you simply disconnect the truck negative, connect the auxiliary braking to the same battery, and, keep the chassis battery "up" with the 7 pin charge wire?
 

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Discussion Starter #6
I thought so but the both M&G and Invisibrake will not guarantee that their systems won't backfeed and make a negative connection. If I knew that the ONLY reason to disconnect the battery is to unlock the steering wheel, I have the problem solved. But if there are sensors on the front that can be damaged by towing with the cable connected, I still have problems. I don't know what sensors on the front would be powered with the ignition off, but who knows what the engineers have thought of. Obviously the back doesn't have any sensors or you would have to disconnect the cable when dolly towing.
 

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Ok, in the event of a breakaway, unless you have someone riding in the "toad", you're gonna have to worry about more than sensors, regardless of braking system.
 

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Discussion Starter #8
True. Mainly lawsuits if I don't have a working breakaway brake system. Hence the problem of disconnecting the power. Some have added a 12v motorcycle battery charged by the coaches 7 way plug. What I need to know is if there is anything that is going to be damaged (other than the steering lock) by keeping the cable connected. The steering lock has been disabled by having the locking ring turned down to where the locking pin doesn't have anything to engage with so the steering wheel cannot lock any longer.
 

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First, I cannot answer why to disconnect the battery. But, disconnect the truck negative, and use the Tahoe battery to power the brake actuator. The way I listed above solves the dilemna.

For a "why" answer, go to gmupfitter.com and email in your question.
 

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Discussion Starter #10
Thanks for the link. I'll try that.
 

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I maybe wrong on this, but don't the "15s+ have electric assisted power steering. And who knows what the engineers over at the GM shop have put in alone with it. And does the stabilitrac system work all the time with key on? Inquiring minds need to know!
 

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Discussion Starter #12 (Edited)
I tried the GM Upfitters but all they said was that their understanding as to why was to prevent the accidental engagement of the transfer case and to prevent "possible" damage to the electric steering. The accidental engagement of the transfer case idea doesn't work because the same problem would still exist when dolly towing yet you don't have to disconnect the cable when dolly towing. As to damaging the electric steering, except for the steering lock what could be damaged if the cable is connected as opposed to being disconnected. Surely the electric steering system doesn't pull power when the ignition circuit is off, does it? I talked to another GM dealer and they said they don't see any problem with leaving the cable connected since the steering lock is disabled. The system for the transfer case is the same as the 2011 Tahoe had and we didn't have to disconnect anything to tow it. There is a relay I can pull on the transfer case but they said they didn't see any real reason to do that. They said I could do the same thing to my 2014 Silverado ( which they sold to me)and it has the electric steering. I would like to know exactly what components of the electric steering could be damaged so I would know what will not be warranted but I guess I'm out of luck since no one seems to know for sure why the negative cable has to be disconnected.
 

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If that is the case, does the electric steering assist go via a ckt breaker or relay? If so pulling it would do the same thing IMHO.
 

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Discussion Starter #14
I haven't found a relay for it yet but I agree that it should work if I can find it. There's bound to be one somewhere. I just don't understand how having the battery hooked up could damage it any more than without the elec. The front wheels are going to turn either way.
 

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I just read the Roadmaster installation instructions and I don't see any issues with it back feeding anything. The only point of back feeding is tail/turn signals and they are protected from doing so with diodes. But if you are still worried that it could back feed some how why not simply install a set of auxiliary lights for the towing system instead of using the vehicle tail lights. This would allow you to disconnect the battery from the vehicle with no chance of back feeding anything.
 

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Discussion Starter #16 (Edited)
I have already installed auxillary lights. My installer contacted Roadmaster direct and he said they would not guarantee that the unit would not backfeed. Disconnecting the battery leaves the vehicle without a breakaway system, which is required in most states, unless you install a separate battery. If the dealer had known his product, I wouldn't have traded the '11 off. The dealer said that towing the new one would be just like the old one. WRONG!!!!
 

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Again, why can't you use the truck's battery, which will be disconnected from the truck, to power the breakaway system :banghead: ?

First, connect breakaway to truck battery positive. Now, and here's the hard part, disconnect the truck negative, and, install the breakaway negative to the truck battery. It can't be much simpler. Take one negative off and put a different negative on.
 

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