Ignition noise.

Two different vehicles, same problem. My 86 GN with an aftermarket CD radio and my 90 Chevy K1500 pickup with the factory stereo, both have the "ticking" and high-pitched tone.

From doing a search, the primary causes seem to be:

-- bad spark plug
-- bad spark plug wire
-- bad ground
-- bad head/amp unit.

To fix the noise, should I ohm the plug wires first, then if they are OK run a dedicated ground to the chasis? How can I tell if a spark plug is the problem?

Any other steps that are recommended to fix the ignition noise?

Thanks,

[salvageV6]

Coupla questions.

Can you disconnect the antenna from the radio easily?

See if it still makes noise with it removed, yeah I know you might not be able to tune a station just see if the noise goes away.

Secondly is the noise there on tape or CD operation?

Could be coming in from the antenna lead.