Im no wiring expert, if you were going to wire an inline switch to disable the EFI fuse/relay where would you do it? I have attached a wiring diagram with 4 possible locations that I can see, are any of these better than the other?

Which one would be the lowest amp rating that would not require a hefty switch to effectively disable? I was hoping to use a 16 amp switch i have on location 3, but have no idea if that is a good spot to do it..

The "From "IGN" Fuse (2-2)" is run off a 7.5 amp fuse, which seems to be actuated when the key is in the on position ( i think).

 

Position 3 involves the least current; just the draw of the relay coil, which is probably much less than 0.5 amps.

You are correct about the 7.5a IGN fuse; it is downstream of the ignition switch.

 

Can you think of any I'll effects caused by interrupting the efi relay at position 3? I hope the ecu would have no lasting impact if it were attempted to be started with that relay inoperable.. Any codes or damage possible?

Thanks for the quick reply scope!

 

Concur.

Final answer: point 3
No ill effect. That's the proper place for one of the many kill switches you can install.

However, please do NOT post where you're finally inserting and mounting kill switch.

 

The wire between your marks 1 and 2 (a Black-Green wire, if you care) provides "always on" power to the ECM. If you opened the circuit at 1 (or took out the EFI fuse), the ECM would lose power, and I expect it would lose fuel trim from one time to the next.

As you might know, the injectors have 12v always to one side, and they are opened by the ECM grounding the terminals labelled #10 and #20. The 12v side of the injector is powered from the ignition switch. SO, if you turned the ignition switch on but kept the EFI relay from closing (so no power to the ECM), do terminals #10 and #20 go to ground (which would open the injectors) or "open circuit"? I expect the latter, as that would be the safest way to design the circuit, but I don't know the answer.

 

Rad, thanks very much for the confirmation on this. I will move ahead and try this out, will be nice to have some more hoops for those thieves to get through.

Scope, sorry I don't fully understand, are you suggesting interrupting the signal to the injectors as another type of kill switch? I had thought about this but wasn't sure how delicate the signaling to the injectors were and thought there could possibly be some degradation of the injector pulses if i added a switch in there. Probably over thinking it tho.

 

I'm saying don't use position #1; you'll lose fuel trim data.

I don't know if cutting power to the EFI relay (which removes main power from the ECU) leaves the injectors closed or open, but I'm almost certainly it would leave the them closed (meaning: #10 and #20 would be "open circuit" with no power to the ECU). Otherwise, turning on the ignition switch with no power to the EFI relay would cause the injectors to spray fuel (from residual pressure; the pump won't start) into the cylinders.

I don't know the answer for sure, but I'm pretty sure that WON'T happen and your plan is fine.

 

Ahh ok that makes sense scope. Thanks for clarifying that.

I dug around in my kick panel and found the correct wire to interrupt, confirmed with my multi-meter. Looking good, thanks again guys for your help!


Bonus Question:

What does it mean when a wire has red tick or slash marks on it? I notice some wiring has this and others don't. Its not referenced (as far as i can tell) in the wiring diagrams.

That it splits at some point?

 

Concur. "W-L" wire into EFI ECU needs to stay on. This must be the one that preserves ECU data. Cutting point 1 will remove power to ECU.

I believe that's correct, too. ECU needs to power up from pins B & B1 coming from EFI main relay. With that off, ECU will not be able to ground pins #10 & #20.




Cool!
Haven't figure what the re slash means, so would appreciate if you shared what you find out.

Bonus idea...
kill switch to interrupt green wire between C.O.R. and AFM contacts would also be a nice, low-power and puzzling kill area Truck will have combustion, but only when ignition is in start position.

 

Why not scrap all that and interupt the starter feed wire.

Same effect as in it won't start, and if your wiring fails while driving the engine will not die and therefore lose your power brakes and steering. Could you steer and stop your vehicle without these in a panic situation of having them go out on the freeway......could your girlfriend/wife/friend/little brother, etc that may drive the vehicle one day?

There is a reason that NOT ONE alarm company in the world interrupts the ignition circuit on any alarm now or ever.

Same work and effect. 100000 times safer for you and everyone that you could potentially hurt. I have never understood everyone that wants to interupt the circuit that drives the functionality of making the vehicle safe to drive.

 

Because it's easy to find and bypass.

That's why everything one does to the truck should be clean and robust.

Yes, the faster the truck is going, the less need for power steering. The faster the truck is going, the less sharp you want to steer it.

Hell no; my wife does not and refuses to learn stick shift - LOL!

Yes there ARE. My Honda Civic can crank but not have combustion when mechanical key without transponder is used. Meaning either fuel or ignition system is interrupted when transponder key is not used. Same concept as when alarm is armed.

 

I so enjoy living where the key can stay in the ignition switch all night.

I still like the chain around the steering wheel and clutch pedal or brake pedal maybe a pain to install but it does work .

 

Was occasionally blowing efi fuse when engaging clutch , now it will pop just after starting truck. any suggestions?

 

Going out to check wiring around ecu & grounds. will check back later , any suggestions greatly appreciated thanks .65Junker

 

I saw a trick once where someone welded a chain link to the trans and xfer shifters, allowing them to be padlocked together when the trans was in reverse and the xfer was in low.

You can steal it, but you'll have to drive backwards slowly!!

 

Wrong thread/post. This post is what to do SO TRUCK WON'T RUN

 

I like the "interrupt power to the starter idea" and a switch under the hood is cool for that method.

 

If your going under the hood anyway, I run a giant marine grade battery disconnect on all my vehicles accept my daily driver. It does reset the ECU, but I've never really had an issue with that. I never have a dead battery no matter how long the trucks set neglected.



You can also get ones that require a key to turn.