I recently installed a 7" Android Head Unit. I would like to get the steering wheel controls on my 1999 Blazer working with it. I have determined with an ohm meter two wires that show resistance when the steering wheel keys are pressed. They each have a unique impedance and are the only wires that are effected when the steering wheel buttons are pressed. The wire colors on the radio harness connector are blue and green. I connect them to the Key 1 and key 2 connections on the head unit but it has trouble learning them. For example when I set up for volume up, the volume up is continuous, as if the button is being held down. I was also able to program the mute button. but that was all. No other bottoms could be programmed.
I have also tried connecting only one wire to Key 1 but I get no response from the radio at all when connected that way..
Do I need an interface for this? If so which one? Is there an alternative to using the interface? Am I making the wrong connections?
I have scoured the internet and forums for information on this with no luck. Any help is appreciated.
Thank you.

 

If memory serves me right, when I hooked my Pumpkin up, I actually grounded one of the factory wires going to the steering wheel controls, and then the other wire went to either Key1 or Key2. Basically the radio is looking for a resistance to ground on the circuit. You then program what function each button does through the settings in the radio, and then it knows which button's resistance value ties to the function you want the radio to perform.

So going to the factory steering wheel control wires, try ground and Key1 first, if that doesn't work try ground and Key2. I don't think polarity makes a difference, so it doesn't matter which you hook to the blue or green. If there's an extra smaller wire labeled Ground on the radio, use this wire for your steering wheel controls ground source instead of having to tap into the thicker main ground going to the radio, as that's exactly what that smaller ground wire is for.



For what it's worth, I don't know if my radio is just stupid or if the OEM steering wheel controls are on the fritz, but I've reprogrammed the buttons a dozen times, and they still only work half the time. It's almost like the button's resistance value changes with temperature change, so after about 10 minutes of driving with either the AC or heater on to change the interior temperature, they will flip out and either send the wrong command or just flat out not work. In my case, I think the radio is looking for such an exact resistance value that the tiny changes are just confusing it. With the same steering wheel controls, I never had the issue with a Pioneer radio using an Axxess ASWC-1 adapter. I may try to go back to using that adapter if I can make it communicate with the Pumpkin android radio.