Hi, my Pioneer 6x9s on my parcel shelf are giving a very low volume but very high squeeling noise which seems to get louder and higher depending on what the engine is doing, basically the squeeling revs with the engine. Any ideas?
A good ground should have exposed bare metal surrounding the connection, should be physically secure, and DIRECTLY to the chassis of the car - i.e. not to a wing or a seat back or other part not part of the shell.
In addition check the condition of the factory battery to chassis earth.
It would be adviseable if you have issues after checking your wiring meets the above specifications to come back here having been to maplins and bought one of their DMM (Digital Multimeters). These are £4.99 and are yellow.
When you have one of them we can go through some simple continuity checks which will quicky determine the issue