I have a 1997 dodge diesel and i am trying to accomplish a high idle system similar to new trucks where you can hit the 'on/off' cruise button to activate then 'set' to increase idle which is seriously needed when it is -35 right now in sask, canada and the snow brush pushing on the pedal isnt cutting it anymore. so i have a system fiqured out to do this but i just need the triggers from each button, would be easy if there was three wires but
-there is only one input(V32) of 5v from the powertrain control module and then one output(V37) wire with varying voltages depending on button.

ON/OFF button is 1.51volts
SET is 3.8v
RESUME is 4.4v

so my question is how can i have each one of these buttons activate say.. a relay. i dont want to be tearing into my steering wheel to tap into the internal switches if possible.
thanks

 

Does the Led come on when the cruise control is on, and stay on until it's switched off? looks to me as if the led is providing a low voltage positive path for the switches terminal 1, and the input uses the resistors to drop the voltage for the cruise input terminal4,

and the ground path is on terminal 3 of the steering control?

So a resistor divider could be used on terminals 1,4,...

 

your right with the led, it does turn on when 'on/off' is pressed and turn off when its pressed again. It seems as this is required first to allow a voltage potential for the other buttons. your correct on voltage drop over the switches as well. so now for say once its powered up, and you use either the 'set' or 'resume' button which i plan on using to trigger two different relays for 'idle up' or 'idle down'. when set is pushed 3.8v is available at (4) and when resume 4.4v is available at (4). is there something that can differentiate the two voltages to trigger two different relays?

 

I would just put the high idle solenoid control on a dedicated switch under or on the dash rather than mess with the cruise control system buttons.

Either that or install the old fashioned mechanical throttle lock system the old commercial trucks used. Pull out and turn to lock at whatever RPM you want.

 

Yes, you can use a window comparator to detect the different voltages, using op amps lm358, lm3914 etc..