Cruise "on" light (GM cruise control adapted to another vehicle)

[steam powered]

Hi Guys. New here. I'm a Mechanical Engineer with some electronics knowledge, but I thought instead of nutting this one out myself, I'd ask the world.
I have adapted a later model GM cruise control unit (Cable throttle style) to another car. The circuit that advises that the control unit is "on" is different to the earlier (and larger) units. Earlier units can basically switch a globe on, the later ones tell a Body Control Module that the cruise is active and it tells the instrument cluster to turn on a light.
I don't have all that so want a small circuit that can interpret the signal.
I'm also presuming that the BCM input would be a high impedance / resistance, hence minimal current capacity through this wire.

Note that the cruise module / system works. All I'm after is an indicator light to show module is powered up. Indicator light currently intended to be a 12V LED (LED, BEZEL & resistor purchased as a unit)

Signal:
Ignition off (& cruise module off): 0.0V
Ignition on, cruise module off: 12.0V (Basically battery voltage)
Ignition on, Cruise module on: ~ 5.9V


Any takers for basic circuitry to light my led?

Andrew

 

[Bluejets]

Pnp transistor with a 5v1 zener on the base, power via ignition.

 

[dorke]

Welcome to EP.
The simplest way would be connecting a "6V LED".

You can purchase one "ready made" or make your own.

If you DIY,
you need to know the LED nominal current and Vf(both very with type,color,size etc.)

Then calculate the resistor value by
R=(6-Vf)/iLED

 

[steam powered]

dorke. Thanks. I tried this and it worked.
Used a 2V LED in a bezel and an appropriately sized resistor.
(I did the same for the cruise engaged signal that was 12V. same bezel, different color LED and different resistor value so they matched)
Thanks.

Bluejets, Thanks for taking the time to reply. dorke's was simpler so I gave it a go first.