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Fuel pump kill switch

Nixxxster

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Hello,
Does anyone know where the fuel pump wire is located? I wanted to install a kill switch going to the fuel pump. Any help would be greatly appreciated. Or is there a better way to install a kill switch
Thank you
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Left Field

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I put in a kill switch on the fuel pump for theft deterrent and it's been simple and reliable. Didn't want to cut into the wire harness so took advantage of fuse block access. Started with an old fuse, using a file and saw blade to remove some of the upper plastic and fuse element, then soldered on wires that connected to an in-line fuse and the remote switch. Made sure to put the in-line fuse on the 12V 'hot' side to avoid a fire if something got damaged or shorted. The switch was rated at 15-20 amps and fairly heavy wire used as the pump draws significant current. Keep in mind if there is anything left to Murphy you can end up on the side of the road or worse.

Since then I've noticed that 'Fuse Extenders' are available on eBay, Amazon, etc. that might make it even simpler (if one can be found that fits the fuse box).

Jeep Wrangler JL Fuel pump kill switch Fuse Extensio
 
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Nixxxster

Nixxxster

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Thank you the reply. So you tap it from the fuse box and ran the kill switch into the cabin?
 

Left Field

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Yes, brought the wires through the firewall and mounted the switch in a discrete and physically protected location. Mostly only use it when parked in dodgy areas. When it cranks and won't start I eventually remember to turn on the switch again, lol
LF
 

Htfan

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I put in a kill switch on the fuel pump for theft deterrent and it's been simple and reliable. Didn't want to cut into the wire harness so took advantage of fuse block access. Started with an old fuse, using a file and saw blade to remove some of the upper plastic and fuse element, then soldered on wires that connected to an in-line fuse and the remote switch. Made sure to put the in-line fuse on the 12V 'hot' side to avoid a fire if something got damaged or shorted. The switch was rated at 15-20 amps and fairly heavy wire used as the pump draws significant current. Keep in mind if there is anything left to Murphy you can end up on the side of the road or worse.

Since then I've noticed that 'Fuse Extenders' are available on eBay, Amazon, etc. that might make it even simpler (if one can be found that fits the fuse box).

Jeep Wrangler JL Fuel pump kill switch Fuse Extensio
So you basically cut the top of the custom loop you fabricated and inserted a switch installed inside the JL? Or did you use a relay?
 

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Left Field

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The picture is of one of the fuse extenders available online, but is essentially the same as what I made. For the pictured extender, the loop would be cut and wires extended to a relay or a switch. I used heavy wire (#12 if I recall) directly to a switch.
 

WashingtonWetWheeler

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@Left Field am I wrong in that the fuse necessary "F04 – Fuel Pump MTR/FPCM
20 Amp Yellow – Micro" located in the fuse box near the battery, is a micro and I can't find any "micro" extensions available online. Looks like the smallest is the "mini".
 

Left Field

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I think you are correct, unfortunately. I've had no luck with an off-the-shelf extender for the newer 'Micro' fuses either. My last application was Mini. If a micro version doesn't materialize soon its likely going to be a 'build my own' solution for my upcoming JL. Might be a good excuse to buy that 3D printer I've been looking at... :)


@Left Field am I wrong in that the fuse necessary "F04 – Fuel Pump MTR/FPCM
20 Amp Yellow – Micro" located in the fuse box near the battery, is a micro and I can't find any "micro" extensions available online. Looks like the smallest is the "mini".
 

WashingtonWetWheeler

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Anyone have any idea where the fuel pump relay is? Might just interrupt that circuit with a kill switch.
 

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TroyBoy

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What about just putting a kill switch in between the start button?
 

Left Field

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I did a little more research on kill switch options. Interrupting the start button is intuitive and might well be the ideal solution but I'm a little nervous about messing with it because of potential complications with the remote start function and the RFID backup start feature. No idea if these are valid concerns.

Looking at the schematics, there were three circuits that seemed like decent alternates:

1) Fuel Injector power
2) Fuel Pump power
3) Starter solenoid power

For those intrepid enough to open up the wiring, all three circuits can be accessed under the PDC fuse board. There are four connectors that attach to the underside of the PDC fuse board:

Jeep Wrangler JL Fuel pump kill switch PDC Connectors


Within each connector the pins are laid out in an 'A-B-C...' x '1-2-3...' grid.

Some info regarding each option below. Note that making mistakes is one of my primary features, so if proceeding, best verify the options using the schematics posted by @x7tristan here: [ Don't burn up that beautiful JL!! ]

https://www.jlwranglerforums.com/forum/threads/jeep-jl-wrangler-wiring-diagrams.19185/


1) Fuel Injector / Coil power
Connector C3, pin B4
Fuse: F70, 25 Amps
Wire size: 14 AWG (equiv.)
Wire color: Brown/yellow
Schematic: Fuses / Relay - ASD - [engine]

2) Fuel Pump Power
Connector C2, pin B5
Fuse: F04, 20 Amps
Wire size: 14 AWG (equiv.)
Wire color: Dark Blue / Orange
Schematic: Fuses / Relay - Miscellaneous [engine]

3) Starter Solenoid Power
Connector C1, Pin F2
Fuse F02, 40 Amps
Wire size: 13 AWG (equiv.)
Wire Color: Yellow / Grey
Schematic: Fuses / Relay - Miscellaneous [engine]


When opening the PDC on my '21 JLUR 392 I found that the fuses, connectors, wiring and colors appeared to match the schematics for the other listed engine platforms.

I haven't implemented a kill switch yet as I'm not 100% comfortable with hacking the wiring on a new vehicle, but if proceeding will probably lean towards the 'Starter Solenoid' option as it seems the simplest and least likely to mess with any computer monitoring or diagnostics. The down sides are that its a relatively difficult (short) wire to access in the PDC and that its fused for substantial current (probably requiring a 10AWG wire run with a beefy high amperage switch, or maybe a remote relay).
 

21JLURDG

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I'm not a diesel expert so I'll gladly take any suggestions here.

1. I believe our 3.0L use an electric fuel lift pump and a mechanical high-pressure pump (CP4.1). Therefore, I assume interrupting fuel pump power at F04 will turn off the lift pump but allow the CP4 to continue running until it runs out of pressurized supply--depending on the engine demand. Pulling on this thread (puns, oh yeah!), it seems a very likely reason for the documented expensive CP4 failures is aeration in Duramax diesels that don't use lift pumps. https://www.xtremediesel.com/blog/2021/09/01/what-is-a-cp4-pump-and-why-does-it-fail/ My thought is turning off the electric fuel pump could be a disastrous $10-15K error.

2. Disabling the starter solenoid will stop someone starting the engine with the start-stop button; however, someone can still easily start it by jumping the contacts directly on the starter. Once the engine is started, the starter solenoid is no longer required. This seems like a weak anti-theft solution?

3. I'm less familiar with fuel injector/coil power. Diesels don't use coils, right? I'm assuming/hoping that interrupting power to F70 will just stop the individual solenoids from opening the injector and forcing the diesel to return to the fuel tank, thereby keeping the engine from starting or running. I'd like to know if this is true, any potential harm to our expensive rides, and any thoughts.

I'm really looking for a safe and reliable way to keep my Jeep from being stolen by the average thief--not by the dedicated expert who will get it no matter what.
 

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I did a little more research on kill switch options. Interrupting the start button is intuitive and might well be the ideal solution but I'm a little nervous about messing with it because of potential complications with the remote start function and the RFID backup start feature. No idea if these are valid concerns.

Looking at the schematics, there were three circuits that seemed like decent alternates:

1) Fuel Injector power
2) Fuel Pump power
3) Starter solenoid power

For those intrepid enough to open up the wiring, all three circuits can be accessed under the PDC fuse board. There are four connectors that attach to the underside of the PDC fuse board:

Jeep Wrangler JL Fuel pump kill switch PDC Connectors


Within each connector the pins are laid out in an 'A-B-C...' x '1-2-3...' grid.

Some info regarding each option below. Note that making mistakes is one of my primary features, so if proceeding, best verify the options using the schematics posted by @x7tristan here: [ Don't burn up that beautiful JL!! ]

https://www.jlwranglerforums.com/forum/threads/jeep-jl-wrangler-wiring-diagrams.19185/


1) Fuel Injector / Coil power
Connector C3, pin B4
Fuse: F70, 25 Amps
Wire size: 14 AWG (equiv.)
Wire color: Brown/yellow
Schematic: Fuses / Relay - ASD - [engine]

2) Fuel Pump Power
Connector C2, pin B5
Fuse: F04, 20 Amps
Wire size: 14 AWG (equiv.)
Wire color: Dark Blue / Orange
Schematic: Fuses / Relay - Miscellaneous [engine]

3) Starter Solenoid Power
Connector C1, Pin F2
Fuse F02, 40 Amps
Wire size: 13 AWG (equiv.)
Wire Color: Yellow / Grey
Schematic: Fuses / Relay - Miscellaneous [engine]


When opening the PDC on my '21 JLUR 392 I found that the fuses, connectors, wiring and colors appeared to match the schematics for the other listed engine platforms.

I haven't implemented a kill switch yet as I'm not 100% comfortable with hacking the wiring on a new vehicle, but if proceeding will probably lean towards the 'Starter Solenoid' option as it seems the simplest and least likely to mess with any computer monitoring or diagnostics. The down sides are that its a relatively difficult (short) wire to access in the PDC and that its fused for substantial current (probably requiring a 10AWG wire run with a beefy high amperage switch, or maybe a remote relay).
Post of the day, thanks for this info.
 

DaltonGang

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Make it easier on yourself. Just disable the electricity, to the starter switch, or disable the battery. Less things that could go possibly wrong.
The battery disabling would be, is it wasn't being used for a while.
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