IDM Relay Security Mod/Re-Modified
<HR style="COLOR: #d1d1e1; BACKGROUND-COLOR: #d1d1e1" SIZE=1 itxtvisited="1"><!-- / icon and title --><!-- message --><!-- BEGIN TEMPLATE: ad_showthread_firstpost_start --><!-- END TEMPLATE: ad_showthread_firstpost_start -->Ok, you guys might think I am insane, or genius... dunno which..
This is kind of in depth as far as electrical circuits etc. goes, so those that are more adept at wiring diagrams etc. please help out.

I looked at the wiring schematic for the IDM Relay/ Security Mod ( https://www.ford-trucks.com/forums/forum5/ )

I wanted to modify this idea so that I didn't have to remember to click the switch "off" in order to protect the vehicle from theft. I also wanted to keep it reversible.

To do this, I wanted to use a momentary switch as opposed to a rocker or toggle switch.

The wiring diagram is about finished.
When looking at the wiring diagram, the 2 relays on the left side convert a momentary pulse of 12v+ to a constant 12v+. This will enable the IDM relay to remain on until vehicle is turned off.

The relay on the right then converts that 12v+ to a (-) output which is wired to terminal 86 on the IDM relay and activates the relay just as the original Mod did.

Here is the link for the wiring diagram (Unfinished obviously)
https://www.ford-trucks.com/forums/album.php?albumid=419&pictureid=1992

The critical bit of info I need to finish this is:
In stock form, what happens to the 30,87,87a,85 terminals on the IDM relay when the truck is turned off?
(I need to either remove the ground or 12v+ signal from the middle relay to reset the system)

Second question is: Is anyone interested in performing this Mod once it has been tested and verified to work? Or (in your opinion) am I over-engineering things?

 

Subscribing.

 

Me too. I like the idea of not having to remember to push the kill switch when I get out.

 

so you need to push a hidden button to start the truck? I like this idea aslong as everything works (ie glowplugs)

 

You could just add another relay and use it as a latching relay to enable-disable the original set up.

 

This mod just disables the IDM so the truck won't start. When the button is pushed everything will work like it is supposed to.

I have no idea what that means Jim. Did you look at his diagram? It looks like he is using an extra relay. I don't know if it's latching or not.

 

I did look at it quickly. Where it's not finished, it's tough for me to see exactly where he is trying to go with it reguarding the ignition.

A latching relay has the coil on a relay energize with the push of a button and deenergize with the same button.

 

Wouldn't a latching relay require you to hit the switch again to shut it off? Thats what I am trying to avoid.

 

It would but if the feed comes from the ign switch then you would have to turn the ign on then hit the switch to energize the relay. When you shut the truck off then the relay would automatically de energize.

 

Why not use an oil pressure make switch to hold a relay in and hold a momentary switch til oil pressure built

 

I put together something similar.

It's described here:
SpringerPop's Disabler

As Jim suggested above, it uses a latching relay. It's a dual coil.

Pop

 

Springer Pop: Read your article quick, find it very interesting... Will have to consider it. Another thing I was thinking was an RFID setup which could be cool and even harder to disable, but if you lose the tags, pretty well skrewed.
RFID Reader with Tags - RadioShack.com

 

I prefer disabling the starter motor. Won't even crank. Everything works but the starter. That is what I did with a switch. Only problem is remembering to throw the switch to open position to disable starter but that can be overcome with the ideas here. Easy to do on any 99-01 that has a starter relay mounted under the hood.

 

The only problem, Robin, with simply disabling the starter, is that it's a super-simple work-around for any car thief, even joy-riders, as this is the most common method to disable a vehicle. A short piece of jumper wire is all it takes to get around it.

I'd go for something a little more complex to slow the bastages down.

Pop

 

The only advantage I see to the IDM Robin, is the thief will recognize there is a kill switch if the starter is disabled, and we know they can defeat the alarm systems that have the starter kill function. With the IDM, they will just assume the truck has something wrong with it since the engine will spin, but won't start.

People might ignore an alarm going off in a parking lot, but natural curiosity will cause you to look when you hear someone cranking on a starter too long with the vehicle not starting.

Edit: Pop beat me to it.