Reminds me of when I bought my Disco.
The driving lights only worked with the motor running
The UHF and CB were the same but stayed on for 5mins after motor turned off???

Well with a bit of hunting found what was wrong..
The above were wired to the 2nd battery which had 2 dead cells in it

Driving lights now on main Battery but left the radios on the 2nd
Hear voices in the drive way late at night sometimes...Mmm, must turn radios off


Also upgraded from a Pirana system to Redarc(with tell tale light on dash) and very happy.