C7 battery draining - infotainment/amp?

Back in Feb I went on holiday and forgot to leave C7 on trickle charge. Came home and with miserable weather didn't take it out. All told approx 4 weeks of standing still with no charging.

Went to start car and battery completely dead. Gave it a full recharge but it kept dropping charge, sometimes car wouldn't start within minutes of finishing a ride. Finally got round to testing battery health and found it was delivering 250 CCA or so. I noticed that when I was turning the car off and locking the door, after a few minutes I could hear a click/thump sound from inside the car, like an amp being turned on. This repeated every few seconds.

Stuck a brand new battery in, all ok but still getting the amp clicking. Pulled Fuse 21 to turn off touchscreen and amp and everything seems fine. I know there is a code DTC B1517 which would sometimes occur when the small black cable to the neutral terminal was damaged, but as far as I can tell my cable is ok. Could the complete battery discharge have caused some issue elsewhere that needs resetting?

Appreciate any guidance!

Additional info; Had the touchscreen on OEM head unit replaced (original part) approx 1 year ago. Had no issues at all until the battery drain event.

You need to say what year and model your C7 is
Common, you need to see what the code is after B1517 such as

Device Power 2 Circuit Voltage Below Threshold
DTC B1517 03
-
Battery Voltage Below Threshold
DTC B1517 07

-
Battery Voltage Above Threshold
DTC B1517 5A

Review

Diagnostic System Check - Vehicle — 2013 Chevrolet Corvette V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2013 Chevrolet Corvette V8-6.2L.

charm.li

and

B1517 — 2013 Chevrolet Corvette V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2013 Chevrolet Corvette V8-6.2L.

charm.li

teamzr1 said:

You need to say what year and model your C7 is
Common, you need to see what the code is after B1517 such as

Device Power 2 Circuit Voltage Below Threshold
DTC B1517 03
-
Battery Voltage Below Threshold
DTC B1517 07

-
Battery Voltage Above Threshold
DTC B1517 5A

Review

Diagnostic System Check - Vehicle — 2013 Chevrolet Corvette V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2013 Chevrolet Corvette V8-6.2L.

charm.li

and

B1517 — 2013 Chevrolet Corvette V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2013 Chevrolet Corvette V8-6.2L.

charm.li

Click to expand...

Thanks - sorry I should have said. Year 2016 model Z06.
I don't have a diagnostic that will read the full code, not sure who is the nearest GM specialist to Hull (or if any members are local I could check in with).

I'll have a look through the manuals you posted.

Updating on this one. Reinserting fuse 21 immediately brings the clicking back and the drain returns.

To narrow it down further, I located the Bose amp under the rear cargo carpet (part number 23404447, UQS 10-speaker variant). With fuse 21 reinstated, I disconnected the amp harness connectors. The clicking stopped. However, with the amp disconnected the CAN bus is disrupted and the headlights and tail lights stay on, which is consistent with the amp being a pass-through node on the bus.

The fault has been cleanly isolated to a single fuse and a single circuit from the start. In my understanding, a BCM that is not issuing sleep commands correctly would typically keep the CAN bus active across multiple circuits, causing gremlins in several systems simultaneously. Everything else on the car sleeps normally. The BCM appears to be doing its job?

Does the clicking relay behaviour, isolated to the amp circuit, after a deep battery discharge, point to the amp's internal relay being stuck in a loop and not responding to the sleep command?

I know it could still be the BCM. I can't completely rule that out without proper diagnostics and I have no easy access to a GM specialist.

1. Before I spend $600 on a replacement amp from a US eBay seller, is there any way to test the existing amp to confirm it is the fault? I have a multimeter but no GDS2 capability currently.

2. Has anyone got a reliable GM/Corvette specialist with GDS2 access? I am in East Yorkshire but would travel for the right place.

3. Has anyone experienced this exact fault and resolved it? Would be good to hear whether it turned out to be the amp or the BCM in similar circumstances.

Any help appreciated.

Have you looked for any other DTCs such as U2508 Audio Amplifier ?

If all other electronics go to sleep after like 10 minutes after ign key off then I doubt the BCM is the issue
as it means BCM commanded RAP which than controls turning electronics off as sleep mode

Can you tell what relay is going on and off, what it is called and where located ?

How about pulling the fuse 21 wire at the AMP X1 connector pin 4
this would allow than the network still be wired but AMP off and see if that resolves the battery drain ?