Kill switch, 1997 k1500 pickup

[618 Syndicate]

Interrupt the starter wire with a normally open push button. Hide it somewhere within reach of the driver seat. Button must be pressed while the key is in the start position or no power goes to the starter.

 

[aj_08]

Interrupt the starter wire with a normally open push button. Hide it somewhere within reach of the driver seat. Button must be pressed while the key is in the start position or no power goes to the starter.

Thanks. To clarify, you mean the power wire going to the starter which is of thicker gauge, or the signal wire that goes to the starter?

 

[evilunclegrimace]

Thanks. To clarify, you mean the power wire going to the starter which is of thicker gauge, or the signal wire that goes to the starter?

Install the button on the signal wire that goes to the solenoid

 

[aj_08]

Install the button on the signal wire that goes to the solenoid

Ok, makes sense since the thick wire comes from the battery, whereas the signal wire is in the dash.

 

[95Noobie]

citing my ignorance here, what is the purpose of the kill switch? If it is a theft deterrant then I assume the switch or relay has to be very well hidden? Where is it usually hidden? I saw a picture on another forum of an added 'toggle' on/off switch above the cargo light switch that someone had wired in, I assume that logically that would not be a kill switch?

 

[Caman96]

Install each of these. Virtually impossible to steal your truck.

http://www.dlcparts.com/images/BoschGuide.pdf

 

[618 Syndicate]

Thanks. To clarify, you mean the power wire going to the starter which is of thicker gauge, or the signal wire that goes to the starter?

Install the button on the signal wire that goes to the solenoid

What he said.

 

[Road Trip]

Interrupt the starter wire with a normally open push button. Hide it somewhere within reach of the driver seat. Button must be pressed while the key is in the start position or no power goes to the starter.

Hello aj_08,

618 Syndicate has the best idea. Using the following wiring diagram from the
Factory Service Manual, let's see what would be the best way to implement
the 'denial of starter usage' function while you are away from your vehicle:

You must be registered for see images attach

Alright, when it comes to a relay, we can either disable it's functioning (the control side)
-or- we can allow the relay to function but interrupt the power to the load that the relay
is controlling.

To keep this short enough that it will actually be read, when you look at the circuit above,
the RED and PPL (purple) wires would be your target if you decided to interrupt the actual
current being sent to the starter solenoid. (NOTE: Note that both of these wire colors are
marked as a '3' in metric wire diameter. If you check out the attached conversion table
this translates to '12 gauge' wire that is commonly used by sparky types.)

Instead, my recommendation would be to interrupt the control side of the starter solenoid.
This way, instead of the 'momentary on' switch having to reliably carry amps of current, instead
we'll task it with making/breaking the milliamps of current required to operate the solenoid.

In addition, the RED & PPL wires are physically run between the Underhood Fuse Block and the
starter solenoid, so having to route this 12 gauge wire from the Underhood fuse block to a
switch reachable from the driver position is more work. And the shorter that a 'high current'
circuit is, the better.

**** How to test kill switch functionality prior to implementation ****

First, locate the Ignition Switch on the diagram. Notice that the switch must be turned by
the human all the way to the Start position. If you follow the wire from the Start terminal,
it then goes through the CRANK fuse. (#8 in the IP {Instrument Panel} fuse block.)

Pull that fuse, and verify that the starter is now disabled when you attempt to start your
K1500. Note that the wire feeding the fuse is yellow, and after the fuse it is a 18 or 20 gauge
purple wire. (Remember it's a lower current control signal for the relay.)

At this point, once you've proven to yourself that you can actually disable the starter with
the CRANK fuse, now you know where to wire the switch you choose in series in this circuit.

And if your truck is an automatic, I think that this is the best overall way to implement the
'denial of starter' to a thief. To further thwart a thief if your vehicle is a stick (and the engine
can be pop started via the clutch) then I'd implement a switch to interrupt the power to the
fuel pump. (And since there's no pressurized fuel accumulator, unlike a carb with local storage
{fuel bowl(s)} a fuel injected GMT400 won't run for more than a handful of seconds at most
before starving/stalling out.)

****

The nice thing about all of the above is that you can prove/disprove this approach in a minute
or so for no parts cost.

And I typed in the above because anyone trying to make it harder for idiots to steal
their GMT400 shares my outlook on life. The less nonsense in life the better.

Good on you for deciding to implement a kill switch. Do your best to make the switch
location and look as counterintuitive as possible. (!)

Hope the above gives you a better understanding of what's involved in getting your
starter spinning.

Cheers -

 

[aj_08]

Hello aj_08,

618 Syndicate has the best idea. Using the following wiring diagram from the
Factory Service Manual, let's see what would be the best way to implement
the 'denial of starter usage' function while you are away from your vehicle:

You must be registered for see images attach

Alright, when it comes to a relay, we can either disable it's functioning (the control side)
-or- we can allow the relay to function but interrupt the power to the load that the relay
is controlling.

To keep this short enough that it will actually be read, when you look at the circuit above,
the RED and PPL (purple) wires would be your target if you decided to interrupt the actual
current being sent to the starter solenoid. (NOTE: Note that both of these wire colors are
marked as a '3' in metric wire diameter. If you check out the attached conversion table
this translates to '12 gauge' wire that is commonly used by sparky types.)

Instead, my recommendation would be to interrupt the control side of the starter solenoid.
This way, instead of the 'momentary on' switch having to reliably carry amps of current, instead
we'll task it with making/breaking the milliamps of current required to operate the solenoid.

In addition, the RED & PPL wires are physically run between the Underhood Fuse Block and the
starter solenoid, so having to route this 12 gauge wire from the Underhood fuse block to a
switch reachable from the driver position is more work. And the shorter that a 'high current'
circuit is, the better.

**** How to test kill switch functionality prior to implementation ****

First, locate the Ignition Switch on the diagram. Notice that the switch must be turned by
the human all the way to the Start position. If you follow the wire from the Start terminal,
it then goes through the CRANK fuse. (#8 in the IP {Instrument Panel} fuse block.)

Pull that fuse, and verify that the starter is now disabled when you attempt to start your
K1500. Note that the wire feeding the fuse is yellow, and after the fuse it is a 18 or 20 gauge
purple wire. (Remember it's a lower current control signal for the relay.)

At this point, once you've proven to yourself that you can actually disable the starter with
the CRANK fuse, now you know where to wire the switch you choose in series in this circuit.

And if your truck is an automatic, I think that this is the best overall way to implement the
'denial of starter' to a thief. To further thwart a thief if your vehicle is a stick (and can be
the engine can be pop started via the clutch) then I'd implement a switch to interrupt the
power to the fuel pump. (And since there's no pressurized fuel accumulator, unlike a carb
with local storage {fuel bowl(s)} a fuel injected truck won't run for more than a handful
of seconds at most before stalling out.)

****

The nice about all of the above is that you can prove/disprove this approach in a minute
or so for no parts cost.

And I typed in the above because anyone trying to make it harder to for idiots to steal
their GMT400 shares my outlook on life. The less nonsense in life the better.

Good on your for deciding to implement a kill switch. Do your best to make the switch
as counterintuitive as possible. (!)

Hope the above gives you a better understanding of what's involved in getting your
starter spinning.

Cheers -

Amazing, I like this approach. Great write-up.

I agree that the feed side of a relay that delivers power to the component, like a fuel pump or starter motor, is a riskier venture as these wires are thicker for carrying more power. Interfering with the red and purple wire highlighted in the diagram can work, but more things may go wrong and increases the probability of risk.

The manipulation of the control side of the relay, similar to the VCM telling/signaling the fuel pump relay to turn on, and in this particular case, the ignition switch yellow wire allowing current to flow once in the starting position to the crank fuse, and then a smaller gauge purple wire used as a signal to the starter relay (goes to the transmission range switch in an auto trans), at the top left of the diagram.

 

[k1500 97]

Yes, I see what you are saying. Good thing about the fuel shutting off mid drive is the truck will stop. Thieves may just ditch it there. With the spark, if the switch does fail the truck isn't going anywhere, in addition, there is always current running in that switch and is a higher risk for problems. A starter switch draws power once for every start and does not need to be on after it starts which is less risky I believe.

Ah i understand what your saying too,