I had an amp that was causing a draw and draining the battery. Removed the amp and the draw went away. Opened it up and found two burned resistors. Resistor 808 and 807

Have not investigated if the resistors can be replaced and that would fix the amp.

Here's another post confirming parasitic draw being linked to those two resistors. I may try a repair, but i ended up buying two amps off ebay for now to use.

Mach 460 rear amps Fix (Also new cobra owner!) | SVTPerformance.com

Also good info in this thread. Resistor values in here
Mach 460 amps in trunk not working | SVTPerformance.com

 

A lot of time resistors fail because an upstream component has failed. It might be must those it might be something else. If you have access to an IR camera often times you can power the device on and see the components that are overheating.

 

I found my head unit was also causing problems. Original Mach 460 radio, kept blowing the 10A fuse after a min or so.

Basically the whole car was one big electrical drain that was killing batteries and needing a jump every 2-3 days. Bought it cheap because of this. Pulled the amp and head unit and problem solved. GEM goes to sleep after 40 mins (which is how it works) and less than 50 milliamps of current at rest.

Of course now I need a radio....

 

Great info, it’s well known that these amps fail causing parasitic drain. I have seen one thread that implied the cause might be connecting aftermarket head units. IIRC the problem is the head units use 12V to activate the amps, but the Ford head unit uses 5V. The higher voltage causes the amps to fail over time. That would make sense with these resistors failing.

 

In my case, stock Mach 460 radio. WHile the head unit itself went bad, my car is a convertible. I saw evidence of water intrusion under the back window that let water drop directly onto the amps. So i suspect water may have gotten inside.

The top was replaced prior to my purchase.

I tracked down another pair of amps. Only one of mine was causing the parasitic draw, but I'm going to replace both and install a spare Mach 460 head unit and see if the issue is still there.