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Old 09-18-2017, 03:15 PM   #1
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Negative Battery Disconnect

I currently tow a 1998 Jeep Grand Cherokee 4 down. I just purchased a 2017 Cadillac Escalade with 2 Speed Transfer Case, that is Dingy towable. From the owner's manual it states that the Negative side of the battery must be disconnected and you lose your presets. No problem with disconnecting battery, I already knew from previous research I would have to disconnect. I want to use a RM-766 solenoid to remotely disconnect the battery which states, not to use on negative side of battery. Also, would like to maintain ground for braking system and lights. I've talked to dealerships and tried to talk to GM on whether or not I can disconnect the Positive side of the battery instead. They all say "I don't see why not, but the manual says the negative side, so we don't recommend it." I suspect it is for safety reasons - to keep someone from touching the wrench to the chassis and shorting the battery. Does anyone know why the negative side needs to be disconnected or have experience disconnecting the positive side on a newer car with all the bells and whistles?

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Old 09-18-2017, 03:37 PM   #2
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It makes no difference other than safety reasons which cable is disconnected from the battery , as long as there is only one connection to be removed. Some vehicles have more than one wire (cable) going to the battery terminals. If the individual wires are removed one at a time , that's when you could run into problems.

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Old 09-18-2017, 04:18 PM   #3
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Hi ! Welcome to IRV2! We're sure glad you joined the gang!

I think you're right about accidentally touching the wrench to ground! Keep her between the ditches!

Good luck, happy trails, and God bless!
Joe & Annette

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Old 09-18-2017, 04:29 PM   #4
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Keeping the negative side connected has nothing to do with "to maintain ground for braking system and lights". All the cable does is connect the ground system to the negative side of the battery.
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Old 09-18-2017, 05:36 PM   #5
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"sky_eye".....Yes, it's just a safety thing so someone doesn't do something stupid. I tow a GMC Canyon that has the same requirement. I use a solenoid like you want to do, to disconnect the positive side. The solenoid also lets me connect the hot side of my braking system to it.

The reason they want the battery disconnected is to protect the power steering. Even when the key is off, the electric power steering will try to center if the wheel is turned.

Lastly, I mounted the solenoid switch in a discreet spot that someone won't push accidentally or out of curiosity. A good spot was inside the glove box. I opened the glove box and mounted it along the lip of the opening.
Don & Mary
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Old 09-19-2017, 07:31 AM   #6
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If you want to keep your presets buy one of these OBD II 12volt Battery Backup Memory Savers and plug it into to the OBD port under the dash to preserve ECM and all other codes etc. Fully charge it first (you'll need a 110V outlet to do this) then plug it into your OBD port. There about $50 or so at Pepboys. Then disconnect the neg bat cable. Do NOT buy one of the other cheaper 9V battery backup systems. They do not work.

This unit will con't to supply enough power to the ECM and other components so you don't lose settings. I use this every time I have to disconnect to work on the MH. This unit when fully charged should have no problem suppling power for several hours till you get to your next destination and then you'll have to recharge it again before you pull out.
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Old 09-27-2017, 08:16 AM   #7
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I am currently having a problem with towing my Chevy Colorado that may "require" the positive cable to be the one removed. Because I have a charging wire from my Coach run to the battery and the ground to the truck ground/frame, even with the negative cable disconnected, all the power remains on, at least in the cab due to the negative being supplied by the Coach. I can't say if the power steering is powered up, but the dash lights and power seat all work.
I am hoping that disconnecting just the positive will allow everything to work as needed allowing the common ground to be supplied for the tail lights and battery charging.
Just because you can, doesn't mean you should!
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Old 09-27-2017, 08:57 AM   #8
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It might depend on which supplemental braking system you use as wel. Our SMI specifically requires the positive to be removed because it uses the existing negative for a grounding point.

Also, I would be cautious about using devices to keep the cars computer powered up since the purpose disconnecting the battery is to prevent back flows of power to things you do not want power to get to (such as transmission components) while towing. Using such devices while stationary is probably fine, not so much while moving.

We lose our presets when towing and the tranny shifts a bit different when reconnecting until it relearns how we drive.

Proceed with extreme caution changing electrical things. You must keep voltage from getting back to the tranny. Use diodes or some other means when wiring rear tailights and supplemental braking systems. The towing and original wiring must remain separate.

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battery, battery disconnect

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