Troubleshooting RCAs

[CharlieBravo]

So I have 2 amps: one for the 4 cabin speakers (2 front, 2 rear) and one for the sub.

I upgraded the sub amp recently (swapped to higher watts); and when I tested it out, there was no sound from the sub. The cabin speakers were fine.

Light on the amp comes on (indicating power) and I measured ~12.5v (engine off) across the power-ground inputs.

With power to the amp, I pulled the RCAs coming from the HU and inserted a pair coming off my phone (headphone jack to RCA). Sound could be heard from the sub.

I really doubt the RCA cables are bad, since they were working before with the previous sub amp.

So do I need a new head unit or is there something else I can try?

Opinions/comments welcomed!!

[Bluevitz-rs]

Make sure the Sub level is turned up if it's hooked up to a sub output on the deck.

[IllusionX]

Your cables could have gone bad from pulling out the old amp.

[CharlieBravo]

So its not the cables...

HU has 3 sets of RCA outputs: Front, Rear, Sub. I unplugged the Rear set and plugged in the pair from the sub amp. I got sound!

So now its definitely the HU Sub RCA outputs that are bad.

Know how to fix?

[Bluevitz-rs]

so you made sure the level is turned up on the sub output?

[derickveliz2]

Did you try to put back your old amp?

D.

[CharlieBravo]

Yeah, I made sure the sub level output on the HU was greater than 1 (range is 0-6).

HU is JVC Arsenal KD-A625.

No, I didn't try the old amp.