Nope, the radio is long gone....But I have disconnected the battery many times since. I really don't care that it comes on quite often, it's that it screws up the mpg and range computer readout everytime I try to use them. Is there a way to just bypass the damn "SYS" thing? What is the "SYS" referring to?
I can help you out with the SYS light if it is an aftermarket stereo. After much help from Jake I know exactly what steps to take to eliminate the SYS light. By the way, from looking at my wiring diagrams of my 94 LT1 a DTC code 72 will fault in module 9 if the SYS light is caused by the stereo. What needs to be done is a simple mod, you need to splice two 1K ohm, 1/2 watts resistors to a hot wire, and the other ends to two separate wires. That will fake out the dimming circuit as almost all new aftermarket stereos do not have a dimming circuit.
Here's a quick check, during daylight, put your finger over the ambient light sensor located directly left of the "Trip Monitor" words. Hold your finger there and see if the SYS light flashes. If it does you have to do the mod. I can guide you through the entire thing. I have a lot of experience reading wiring diagrams so looking at the DTC codes I got I did some research in my FSM. The DTC code 72 on the EBTCM module may look like it is a faulty transmission speed sensor but that circuit is tied in DIRECTLY to the radio system because the stereo volume is supposed to increase when the car is sped up. The DTC code 72 (coincidence) in the CCM is the ambient light sensor. Don't throw any parts at it until you do the mod.
I can tell you how to use the trip monitor panel to reset the codes, drive it a mile or so and interrogate it again and then we will see what modules are giving what DTC's. I will be happy to help you if you do not have an FSM.
Chevy was very clever in the way they used the OBD plug in conjunction with the trip monitor buttons. You can tell it to run a complete check on almost every single system on the car. Relays will click, things will activate, etc. It is cool. JUST like an airplane. I love this thing now that Jake has enlightened me on how to use it and I would be totally lost without the FSM.
That radio and the SYS light and the accompanying DTC's are almost entirely because of the new stereo. There are so many wiring diagram connections to the CCM that will cause a DTC which are all linked to the stereo, I could not believe it until I spent an evening cross referencing every single wiring diagram that relates to the radio head. What a complicated mess. I just wish I knew if there is a stereo out there that has auto dimming, and auto loudness.
Let me know if you need the help. I have the TSB and the diagrams and detailed instructions on how to do it. I plan on doing mine as soon as I can take it out of service and I am going to take detailed photos and make a detailed description on how to do it. In fact, today I brought the diagrams and the TSB to Best Buy to help any future C4 owners that will be scratching their heads over the SYS light.
Much thanks goes to Jake and others who pointed me in the right direction.
Paul