[dhpnet]

With the green screen radio, there are only 3 wires on the controls connector. Pin 1 is B+ voltage. Pin 2 is ground. Pin 4 is communication wire that connects to pin 3 on the green screen. The radio communicates with the screen and the screen communicates with the controls.

I would first test the ground connections
- Connect a meter between terminal 2 and ground. If you get less than 10 Ω then the ground is good. If you get more than 10 ohms, test for less than 2 Ω in the ground circuit end to end. If more than 2, repair the open in the ground circuit. If less the 2, repair the ground connection.

Next, I would test the B+ circuit.
You can test for voltage on Pin 1, but the preferred method for doing this is a test lamp. The test lamp will load the circuit (a meter does not load the circuit). Connect the test lamp between pin 1 and ground. If there is any resistance, the lamp will not light. If the lamp doesn't illuminate then there is a short (and a blown fuse) or open in the B+ circuit somewhere or a problem with the BCM, power relays or related circuits. If the lamp illuminates, then the B+ circuit is good.

Next, I would test the data circuit
Turn the ignition on and test for 2 to 11.5 volts between the data circuit (pin 4) and ground. If there is less than 2 volts then there is either a short to ground in the data circuit, or the screen is bad. If more than 11.5 volts, then there is either a short to the voltage circuit, or the screen is bad.

If you are going to just swap parts, then I would suggest buying used parts on ebay. It will be much cheaper than buying new parts, and if you find that the part isn't the problem then you didn't spend as much.

 

[dhpnet]

Again - do you have side detection sensors. If you do, and they have shorted, they can wreak all kind of weird havoc inside the car.

Is it possible to have the side detection system with the green screen radio? I thought that required My Link. I think those were both part of the technology package?

 

[dhpnet]

Can't even bench test these things any more, data link sends a code to the radio to turn it on, very similar to the remote on your garage door opener. Claim they do this for a thief deterrence to protect you from this, only your dealer has the tools to check that code.

Just like the computer you are typing on, can be a software or a hardware problem, so you try to reinstall the software to learn if this solve the problem, again, only your dealer can do this, called a reflash. Luck is have a low voltage or a power on reset problem, this you can doing something about, anything else, take it to your dealer.

Its not a radio, its a computer, with firmware stored in flashram.

There are a couple guys on YouTube that setup systems to bench test the OEM radios. One guy setup a ECM, BCM and a bunch of other components to simulate the car's actual working environment. The other guy just connected it to a laptop with a serial connection of some sort. He found out that the BCM needs to send a code to the radio every few seconds to let it know that it should keep working.

GM should be required (by statute) to make all of the serial data information freely available to anyone who owns a GM car. They are trying to make it impossible to take the car to anyone else for repairs, and that should not be allowed. I should be able to take it to anyone I want, and that person should not have to buy a GM scanner or pay GM for access to the data. The data is not really that complicated, it is just proprietary, and GM is not sharing. Some people have reverse engineered the data.

Also, there is no reason to include car configurations in the radio. That could all be done through the DIC. If they separated the car configurations from the radio, and had an industry standard for communications with the radio, then people could more easily install aftermarket radios without problems. This too should be regulated in my opinion. Imagine if Apple or Samsung were able to build aftermarket car stereos that could easily plug and play with your car and your phone. You would have something much better than what GM created. But GM doesn't want you to upgrade your stereo. They want to sell you a more expensive car to get better technology, and the car to become old and obsolete so that you buy a new one.

Aftermarket radios could still have theft deterrent systems that register your VIN from the serial data. That wouldn't be very hard at all if the car manufacturers made the communications standard and shared the information.