2000 C5 Auto Transmission. Bone stock.
Battery and alternator was replaced last November by previous owner.

Two days ago, when going to turn the on the car, there would be a loud whining sound and then after the 2nd time trying to start the engine, the engine turns on and runs and idles fine.
This morning I went to turn on the car and then the engine turned on but a loud whining sound and then I immediately popped open the hood and there was white, electrical smelling, smoke coming from the battery side of the engine bay. Then the engine shut off on its own within 10 seconds. Now the engine will not start and showing the P1518 code.
According to the forums and other sources, the P1518 code pops when there is a missing signal between the TAC module and the PCM.
I do not think the PCM is bad, but maybe the TAC module is now, or at least connected wiring.

According to the battery voltage gauge, the voltage is around 12V.
I removed the inspection panel located behind the passenger side front wheel to inspect the TAC module and PCM, and there is a moderate amount of corrosion due to battery acid leaks over the years I assume.
I need help with tracing where exactly this white electrical smoke may have came from so I can try and move forward with my troubleshooting and replacing the bad part.
I checked fuse #17 in the engine bay for "Throttle Control" as that is associated with the TAC module.
When key is turned for the ignition to be on, I can hear the fuel pump prime still, but once I turn the key to crank the engine, there is no sound and the lights on the dash turn off until the key is turned back into the "ON" position.

Any other requested information to assist in troubleshooting can be provided. Thanks all!

 

Loud whinning sound is not good, it sounds like maybe your starter is staying stuck on after the car has started. You should inspect the wiring under the battery, the electrical smell could have come from the battery cable that connects to the starter. This is just an educated guess, but whinning noise after you start the car are usually starter releated.

 

Unfortunately we can tell you where this smoke is coming from…a P1518 can be caused by low battery voltage so it’s best to check your battery voltage with a DVOM AT the battery…12 volts is less than 50% charged.

 

Today I got underneath the car to start the replacement of my starter. I could see on the bottom of the starter through a “peep hole” that the internal of the starter motor looks charred black. I am hoping the electrical smoke came from the starter motor and NOT any of the associated wiring as that will be a bigger PITA.
Will keep updated on what the outcome of the starter replacement is.

 

Charred black internals of starter motor through “peep hole”

 

Replaced the starter. This fixed the no start/no crank issue.
I suppose the P1518 code was somewhat irrelevant to the fact that the c5 would not start.
P1518 code is no longer current

 

Good to hear, thanks for posting back the results.

 

Turns out, the P1518 code was most likely due to a low voltage battery due to me trying to start the car over and over after the starter burnt out. The P1518 code was somewhat irrelevant to the starter burning out. It’s been over a week with the new starter and no more issues to report related to a P1518 code.