Dashboard lights blackout when brake applied

[akaNYr]

I just bought an 86 300ZX 2+2 A/T NA. Every time I apply the brake the whole dash goes out for a millisecond then comes back on. My whole dashboard is digital. The other problem, possibly related to the blackout, is my battery drains super fast. The alternator is new, previous owner replaced it a month before I bought the car. How do I test for the short & where do I start?

[evildky]

Aftermarket radio? I've seen a lot of bad stereo installs incorrectly ground to the illumination circuit.

[akaNYr]

Yep previous owner put in JVC digital detachable face stereo. He left wires coming thru firewall with clear fuse box just hanging by the battery. He also left 2 RCA jacks & a bare ended wire under the rear carpet touching the metal! It's probably what killed the battery within a few months, I had to go exchange it. Could bad radio install also be causing my volt gauge to be pinned to the top, above 16 volts, while the car is in parked and idle? BTW thank for your reply.

[evildky]

Never seen a voltage gauge do that, but removing all the aftermarket wiring sounds to be a step in the right direction.

[Desert Rat]

check grounds too. Dash lights and tails are typically on the same fuse in a Nissan.