Hi there. I am having a difficult time finding ground in the passenger footwell. There is a thread end of a bolt sticking out from the rear of the firewall. But I can't tell if it would be ground.

How can I test use a voltmeter?

 

Photos are worth a few words.

Frame is ground. DC won't fry without ground. If a volt meter is secondary, a simple spark will answer your question.

If you use a voltmeter, turn the meter to DC and find a power point with the red lead . Contact the black lead with the possible ground and if your connection is correct, you'll get around 12 volt with the car off.

 

^^ what he said and if also run a resistance check between the bolt and the negative terminal of the battery - if the resistance is Zero or close to it, you have a great ground. This is good to do especially if you are connecting a radio, antenna or anything that can interfere with the entertainment system.

 

Thanks guys. Found great ground. Unfortunately the DSC is still interfering with something in the car and still creating an " eeeee" sound

 

Well, your so called great ground is obviously not so great if attaching the DSC system is causing noise to get into your audio. This is typically caused by "ground loops" where there is a current flowing through the ground circuit due to the ground not being really at ground. Your best bet is to run the ground directly to the battery with high enough gauge wire so that there is low resistance.
You may also want to talk to the DSC manufacturer about this. It could also be poorly designed electronics that have bad grounding or filtering of their circuits.

 

Thanks I have grounded the EMF wrap to the chassis. Measured with the multimeter, it zeros out. The only other system that I have is the dension and that is tapped into the footwell lighter socket. There is no other aftermarket device, I have installed in the car. Plus, I don't think it is coming through the audio. Reason, it is intermittent. Once the car is at rest, the sound will stop after a few seconds and will reappear once the car starts to move again.

This is now all pointing to The TPS DSC module. Others have had the same problem with no other electrical mods to their cars.