Have 1997 xk8 with mutfiple electrical glitches too numerous to mention. Worse one is identifying the shell shaped indicator of some type that is located just left of the P (parking indicator) on the shifter panel. When it glows red most electrical systems shut down including the starter. Eventually (overnight) the indicator turns off and power is restored.

 

kayaker48, your symptoms are most likely caused by 1 of 2 things. The easy one is you may have a battery that is starting to fail and is outputting too low of a voltage, causing all the computers to see incorrect readings, leading to the christmas tree of lights that you are seeing. You can remove the battery from the car, take it to a local auto parts store and they can do a load test on the battery. It should be up above 75% capacity. If you are below that, then it is time for a new battery and then see what you have then.

From there, you most likely have a bad ground wire. now, this can be the battery cable itself that is causing the issue, but it could also be a ground that is running between the cabin of the car and the engine and/or cabin to the frame of the car. When you get one of these issues, you may find that if you run say just the car, all will be good. But, as you start applying more electrical load (ie, dash fan on high, seat heaters, etc), the problem raises its head. What is happening is at low currents, where the ground wire is failing is capable of handling the current without getting too warm. But, as you apply more load/current, the high resistance spot starts affecting the voltage, leading to erroneous problems. I had a 79 Dodge Colt that had this problem. You start the car, it was fine. Turn on the headlights, they were fine. You turn off the headlights and turn on the radio, that was fine. But you turned on both the radio and the headlights, all hell broke loose. I found it by turning on everything electrical in the car. I suddenly got a light to turn on in the engine bay. When I went to check out this light (as there was no light bulb in the area), I found a wire the diameter of a pencil glowing white hot, sitting right next to the fuel line. Yep, pucker factor right there. Not that I am recommending finding the problem that way, it may be about the only way to find it. The resistance I am talking about is around 0.1 to 0.3 ohms. Far smaller than what most multimeters can determine. This is where you are going to have to do it a different way and apply some decent current and then measure the voltage drop from end to end of wires (specifically ground wires). A good wire will have less than 0.5 VDC drop from one end to the other. If you are over 1.0 VDC, then that wire needs to be removed and upgraded to either a new wire or to a larger diameter wire. You start getting too high of voltage and a good current, you can develop toaster elements in the car. Think of it this way, power is the multiplication of voltage times current. So, think about an incandescent bulb that is rated for 60 watts. Think about how hot that got after 10 minutes of use. Now, if you have a ground wire with 1 VDC drop and is pulling 60 amps, that wire is dropping 60 watts of power in the form of heat. So, imagine how hot that wire is. Now, how close is it to a fuel line or something else that can catch on fire inside the car?

If you want to try and figure out this problem down to a wire, let me know and we can go from there. Just need to know your electrical abilities as this is one of those problems that it will be a challenge if you are not electrically inclined.