Doing that bypasses the IBS, which keeps track of the flow in and out of the battery. The data from the IBS is used by the system to regulate charging.
The Red A! is telling you the Aux Battery failed the startup test. You can charge each battery and reset the IBS, and get a little more use out of them, but they are at the end of their life.
The ESS is always active, and will still function with the Aux Battery deleted. Using a Tazer, or...
It's a design quirk. Most of the time it was not a big issue. I bought one of the relay harnesses that plugs into the factory wiring. It disables the license plate lights when it is in reverse.
The 56584 harness connects between the trailer plug and factory wiring. It provides a five pin connector with the Tow Wiring for lights. The 58540 harness breaks it out into the separate lines. I used it to connect the reverse lights I added. It should work for a brake light.
There are already holes in the back corners of the bed that can be used. A Curt T harness can be used to connect it to the Tow Wiring to keep the factory wiring from being damaged.
Jeep is the warranty provider. They clearly state that the transmission needs no maintenance, under normal operating conditions. Changing the fluid sets you up for the possibility of a warranty denial, especially if you do not use the Mopar Transmission Fluid. It all depends on the dealer.
The reverse clunk is common and not really an issue. The shifting may become an issue. Changing the fluid just sets you up for a warranty denial, especially since the dealer has already said there is nothing wrong with it right now.
Both of mine have had the reverse clunk with a cold...
There's no direct warning about low voltage, but there are some alerts.
At each startup, the Aux Battery is separated from the Main Battery and a voltage reading is taken. If it is below a certain point, the Red A shows up along with a ESS Disabled message.
When the voltage level is low...
I find these threads interesting, but it's always a repeat of the same stuff. A lot of wishful thinking, and no real acceptance of the reality of the situation. Even with the inside man telling them it's not going to happen, the dreaming continues.
The current design cannot remove enough...
That comes when the Aux Battery fails the startup test. It may be in better shape than the Main Battery. Disconnect the Aux Battery Negative cable from the IBS to measure it.