Sampling CA ThO Throttle Output with Arduino Circuit Problem

[hillzofvalp]

Hey guys.

I am sampling the Throttle signal from the CA in order to automatically control headlight and brake light.

The code logic is as follows:
0-1V (shutdown lights)
1-1.25V (solid LED brake light, turn on headlight);
1.25V+ (blinking red brake light, turn on headlight);

Here's the issue:
The Arduino and CA seem to be interfering. I'm seeing the throttle voltage slowly ramping up. What is the best way to address this? I figure some isolation but not sure the best method (opto isolator?).


I have some of these guys:
http://www.farnell.com/datasheets/89573.pdf

THanks

 

[hillzofvalp]

I'm now tapping the throttle before the CA and getting great results. Only thing is that the throttle voltage rises from .94V to 1.00V. but I can correct that in CA.