A012 is the low side temp sensor circuit fault. These are the small sensors on the upper high side line-both sides of the orifice tube low side temp being closest to evaporator. I believe these are 5 volt sensors, you might be on the pressure sensor. It sounds like you may know how to access the on-boards, if you can access ACP data, parameter AD28 is low side temp. Check it's reading, if it is high(94 to 102), disconnect and see if it registers -40. If it does, replace the sensor. These sensors fail, sometimes the orifice tube is installed backwards and it shears off the thermistor, and there could also be connection faults with the micro terminals. GM offers a replacement connector with leads that attaches in place of existing connector with butt connectors(or solder is an option). When you remove these sensors, the system needs to be discharged. You can try swapping one sensor with the other and see if your code changes. A011 would be the code for hi side.
Wednesday, September 2nd, 2009 AT 10:13 PM