702Rubi

Recently, my 2105 Rubi died in the boonies. That situation is documented here:

https://www.jk-forum.com/forums/stoc...d-help-323925/

At one point, a friend tried to explain over the phone a method of starting the vehicle by jumping 12VDC directly from the battery to some place on the starter and/or starter solenoid.

Of course I was not at the vehicle when I was talking to him, so I couldn't tell him what things looked like on my jeep and have him walk me through the process.

Though it may or may not have helped me then, this sounds like a useful thing to know! But my knowledge of vehicles and their systems is spotty enough that I didn't instantly understand how to do this.

On the internet, I've found either very generic info about this trick, or info that's very specific to some vehicle other than a late-model JK. Some of this advice sounds very sketchy, such as shorting terminals with a screwdriver, etc. And it's often aimed at older vehicles.

I'm sure I could identify the starter on my vehicle, but I'm not sure where I'm supposed to apply the juice. For all I know, everything may be sealed and inaccessible. (As I type this, the Jeep is in the shop.) Also, I don't know if the key or transmission shifter needs to be in a certain position to allow a start. Etc.

Would anyone be able to explain, or even illustrate with photos or video, how to do this safely? Or point me to something that is fully applicable to my vehicle? I have a 2015 Rubi Unlimited with an auto trans.

Note I always have a "Jump-n-Carry" with me, which could serve as another source of 12 VDC.

I imagine I would only do this as a last resort to get the vehicle out of the boonies. I wouldn't plan to do this in my driveway or anywhere in range of my free roadside assistance.

702Rubi

So none of you gurus have any idea how to do this on a 2015 JK? Or if it can be done? Or if it SHOULD be attempted, even as a last resort?

planman

I don't recall anyone ever needing to try this.

From your other thread, it seems likely that something relating to the aftermarket alarm installed by the dealer was the instigator of the problems.

I don't know that it is very common for aftermarket alarms to be installed on JKs that have stock alarms.

702Rubi

This is an old trick for starting vehicles, not necessarily related to my specific problem, or to Jeeps in general. I've never had to use it and I'm not sure how to do it or if it can be done on a 2015 vehicle like mine.

Given the level of knowledge demonstrated elsewhere on this site, I'm surprised no one can address this!?

Off topic: As for my specific breakdown, at this point, we don't know what caused it. Since something is still preventing the vehicle from cranking, the aftermarket alarm (even though it's supposedly disabled) is suspect.

It wasn't my idea to install the aftermarket alarm. Sahara in Las Vegas, NV installs these stupid Karr Alarms on every vehicle they get on their lot. I didn't like it. But this was the only Rubi equipped the way I wanted it that was available in town at that time. And I was without a vehicle and driving a rental car so couldn't wait weeks for another vehicle to show up.

MikeRM

If the reason it wouldn't start was due to the alarm, even if you jumped the starter, the computer may not signal fuel and spark to run.

tom_callahan

Very likely this is possible on your 15 Rubi, here's the details.

When starting the vehicle (with a key) as you turn the key you are powering several sets of circuits. In order they are something like "Accessory", "Ignition", sometimes Ignition2 or Ignition3, and then the final turn is cranking the starter (supplying 12v to started circuit). Once you let go from the final cranking key position, the key falls back into the Ignition power location, which keeps the power supplied to both Accessory and Ignition while the vehicle is running.

If you wanted to jump 12v straight to the started, you need the key to be in that powered position for Accessory and ignition, and then would need to power the 12v feed to the starter manually. It's a short pulse, so you don't keep it connected, you apply 12v until the engine fires up.

If the vehicle has power, but is not cranking, likely you have an alarm system that has a "starter kill" system in place. This is simply a relay that interrupts the flow of 12v to the starter, and is 99.999% of the time located just under the dashboard near your feed. Simply removing the relay will not defeat the starter kill, you need to manually reconnect the starter cables. Another option is to determine if the relay is activated by power or ground from the alarm and then disconnect it from the alarm and provide the power or ground directly. This will switch the relay and enable the starter to fire again.

Hopefully this makes sense. Crappy aftermarket alarms are notorious for failing, and then leaving a vehicle unable to start because the starter kill cannot be deactivated. Understanding how a starter kill is wired and how it works will help you out in the field if for whatever reason it fails. This can be the difference between driving away and being towed for something you can address with some basic wiring.