MK5 Battery Cut Off Location

[MakoGT350]

Hey All - I can not find anything in the manual on battery cut off location for the MK5 and I am just looking for some recommendations.
I get, that ultimately, I can place it where ever I want - but I am having a "creativity block" because there is so much uncertainty about how the dash fits, etc that I am having trouble visualizing what would work best.
I saw Ricksters placement in his build thread, and that may be how I proceed, just wanted some other options.

If it helps, I am doing a complete kit MK5, BP 347, battery at the front, power steering and FFR remote booster

I would like it accessible in the passenger compartment, preferably from the driver's seat - but discreet

[2nd2none]

This is a pic I took of the MK5 in the Factory Five booth at SEMA a couple weeks ago. Looks like the battery cutoff is under the dash on drivers side.
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[Dave Howard]

I bought aluminum pieces from Snakebite to cover the bottom of the transmission tunnel. This makes a nice compartment when the FFR supplied front transmission cover is in place. I’m routing electrical harnesses in this area and have installed the Coyote PDB in this area along with the 250A fuse. I bought the FFR cut off switch and decided not to use it. I’m using a smaller switch with a removable key. It will be mounted on the FFR supplied front transmission cover just under the dash. Tackling the electrical elephant now. Lots of modifications to the harnesses.

[MakoGT350]

Thanks! I was there, but I am terrible about taking photos.

[michael everson]

Personally I wouldn't use it. Just one more failure point and more high energy wires to run. The battery is very easy to get to if you just want to disconnect it.
Mike

[rickster991]

I placed mine for convenience /storage. I can shut it off when I’m working in the car and when I leave it in storage. Having it near you when driving would be ideal for safety purposes. I may move it some day.

[Mike.Bray]

Mine is under the hood, in theory I can lock the hood for a little extra security. In theory.

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[ironman16nc]

On the MK5, it looks like they intended it to fit here. The bracket they provide fits and there's just enough room between the squares for the amazingly large switch itself.225059

[Pete&Scott]

Battery cut-off switches are currently backordered until sometime in April-May 2026. From what I gather, the previous supplier is no longer making them or is unable to make them, and they had to find a new supplier. I will probably skip adding one in the cockpit. Maybe add one when I receive one somewhere in the engine bay, just to make it easier than having to disconnect the battery.

[Jeff Kleiner]

Battery cut-off switches are currently backordered until sometime in April-May 2026. ...

No needto wait for FFR. They are readily available elsewhere, both with fixed handles and removable keys with prices ranging from under 20 bucks to over 100. Check out Summit, Speedway, Jegs, West Marine, Amazon and more. I put one on my old Mk3 and a couple of the cars I've built but most have not (none on my Mk5). They offer very little in the way of theft deterrence and as Mike said create another failure point.

Jeff

[CraigS]

I had my MkII for about 16 years. The first 8 or so I had a switch in the trunk. The last 8 or so I had moved the battery to the engine compartment and skipped the cutoff switch. I never missed it.

[edwardb]

Aside from whether a switch is needed or not (your choice, I'm not going to debate it) my Mk5 kit came with one and I installed it near to the top of the RH footbox. Discussed where and how I wired it in my Mk5 build thread. Same location as I installed one in my Coupe. It's mostly hidden there and available when you want to use it. The Mk5 does seem to have an intended location on the transmission tunnel. There's a bracket with a hole. But I didn't want it there. Not mentioned in the build manual that I could find.

In the past they didn't come with the kit and I used a Ron Francis MS-1 switch. Robust piece that I've recommended in the past and widely available.

[Myron Nelson]

I didn't run one. A switch is inherently five more connection points for failure. Plus I went with the deluxe gauge package with the clock and didn't want to have to keep resetting the clock or run an additional hot to the clock which kind of defeats the purpose. To each their own.

[edwardb]

I didn't run one. A switch is inherently five more connection points for failure. Plus I went with the deluxe gauge package with the clock and didn't want to have to keep resetting the clock or run an additional hot to the clock which kind of defeats the purpose. To each their own.

If you're installing an EFI system, most want the PCM power to always stay on. Ford Performance for the Coyote specifically says don't power it off. There are a couple ways to do that with a master disconnect for the rest of the car. It doesn't have to be a binary decision. The clock can be part of that "always on" connection. But, like you said, another option is to not have a switch in the first place.

[MARIAH]

A Mark I so battery is not easily accessed.
My cut off switch is behind the Driver seat.
Very easy to reach with right hand to reach the Red Key.
I turn it off EVERY TIME I am away from the car and when she is at Home. Very Easy.
When traveling I remove the Key overnight.

[rich grsc]

If you're installing an EFI system, most want the PCM power to always stay on. Ford Performance for the Coyote specifically says don't power it off. There are a couple ways to do that with a master disconnect for the rest of the car. It doesn't have to be a binary decision. The clock can be part of that "always on" connection. But, like you said, another option is to not have a switch in the first place.
Don't know about the Ford PCM for a Coyote, but that isn't true for any of the aftermarket EFI's I have seen. They don't need a standby 12v, all info is on a non-volatile memory chip

[Mike.Bray]

Don't know about the Ford PCM for a Coyote, but that isn't true for any of the aftermarket EFI's I have seen. They don't need a standby 12v, all info is on a non-volatile memory chip

Yep, I've never run across this in aftermarket ECUs like DFI, Fast, or Holley. I have a Terminator X that I was going to install on my Cobra but have repurposed if for my Camaro. It has sat on my credenza for months and when I recently powered it up the tune was all 100% intact.

[BEAR-AvHistory]

I didn't run one. A switch is inherently five more connection points for failure. Plus I went with the deluxe gauge package with the clock and didn't want to have to keep resetting the clock or run an additional hot to the clock which kind of defeats the purpose. To each their own.

If you jump the switch with a light duty fuse all your need to stay hot items will continue to function with the switch turned off. The fuse will fail if there is an attempt to start the car with the switch off. Mine is between the seats on the Ujoint cover.

[edwardb]

Don't know about the Ford PCM for a Coyote, but that isn't true for any of the aftermarket EFI's I have seen. They don't need a standby 12v, all info is on a non-volatile memory chip


Yep, I've never run across this in aftermarket ECUs like DFI, Fast, or Holley. I have a Terminator X that I was going to install on my Cobra but have repurposed if for my Camaro. It has sat on my credenza for months and when I recently powered it up the tune was all 100% intact.

Thanks guys. I stand corrected. I can only confirm that Ford Performance is very clear about the Coyote control pack. Clearly the Coyote PCM has non-volatile memory. Disconnecting power doesn't affect the tune (aka calibration). Maybe more. But in the section of their instructions for hooking up battery power: "Note: This lead MUST be hot at all times (HAAT). If this lead is connected through a switch, the Keep Alive Memory (KAM) of the PCM will be cleared whenever the switch is opened. This will result in loss of diagnostic trouble codes, adaptive fuel parameters, and other information stored in KAM by the PCM." I've heard of guys ignoring this and switching their systems off and claiming no issues. But for my Coyote builds, I just wire it to the hot side of the switch as I previously described and switch everything else. Easy.

[rponfick]

Personally I wouldn't use it. Just one more failure point and more high energy wires to run. The battery is very easy to get to if you just want to disconnect it.
Mike

I am with Mike, I use the simple one attached to the battery post under the hood. No complications running extra wires, and easy enough to get to. May not be very convenient is battery is in the trunk.
Ralph

[Jeff Kleiner]

If you jump the switch with a light duty fuse all your need to stay hot items will continue to function with the switch turned off. The fuse will fail if there is an attempt to start the car with the switch off...

On the cars that I have incorporated a battery cutoff I've used a low amperage self resetting circuit breaker between the terminals. 5 amps is plenty to keep the clock or keep alive memory powered up but will trip if there is a high energy malfunction. If you forget to turn the switch back on and attempt to start the car it will pop but then reset itself (something that I've done on a few occasions :p) whereas with a fuse you'll have to access and actually replace it.

Jeff