Quote: Originally Posted by Canuck_2k
It's just one wire for the LED on the HVAC to the toybox. One to ground.. one to toybox. ta-dah
Haha. It's not quite that simple. There are two options.
1. Drive the LED from the PCM in parallel with LED already in the Toybox.
2. Drive the LED from an extra pin on the Toybox microprocessor.
Potential problems with 1: I'm not sure if the PCM has enough drive to handle two LEDs in parallel. I will need to make measurements to see how the PCM handles it. Odds are good that they used a big enough driver to handle way more current than we need for two LEDs. In that case, you would just need to put a 1k resistor in series with your LED and hook the other end to 12 volts.
Potential problems with 2: I intended to drive the second LED from a spare pin on the microprocessor to avoid the problems with solution 1, but it turned out that I needed that pin more than I would have liked for the display dimming solution. So, it might turn out that the LED would be sort of on when off and sort of off when on. It might not show a big difference between off and on, making it hard to read.
So, you see why I need to do more tests and try these two options out...
