Head unitsays amp error

Pioneer agh-1400dvd you did a typo" G = V, ouch that.
no story told or car told
just installed it in a car and fails? there is a story for sure.
the 3 free manuals never once mentions theft or secure or passwords.
so must be CAR alarm set off, but NO CAR TOLD AT ALL
.year, make ,model
and means it was installed wrong
and has odd parking brake connections, I can not imagine why.
and a microphones, ?
https://www.pioneer-car.eu/eur/products/avh-1400dvd/support

see install guide do as it tells.
but if keeps failing ask them for direct support. it is their DESIGN.

it means there is a disc stuck inside the unit, try disconnecting the battery for a minute and see if it will reset, if not the unit needs to be opened up, sometimes foreign objects can enter like coins etc. You can remove and open the cover to retrieve anything that may be stuck and remove the discs as well, if that is not an option for you then you can remove the unit and take or send it to an authorized JBL or other repair facility that can do this sort of repair.

images for 2003 expedition radio wiring

The humming sound prior to cutting out could indicate a short in the unit itself.....remove unit and have it tested!

There could be several reasons why the head unit for your car does not work. The most likely issue is that the head unit is not compatible with your stereo system. You can consult your vehicle owner's manual for speaker issues.---------------------------------------------------------------------------------------
Diagnostic VAG

1. Disconnect the light green lead at power connector form ur Pioneer Player.
2. Connect above mentioned wire to direct fuse box with steady 12 V supply.

The head unit should have a RCA Sub Out. The RCA wire goes to the Sub Amplifier, along with power, ground, and a blue remote wire from the Head Unit. Next, the Sub Amp is wired to the Subwoofer with speaker wire. Without an amplifier your sub won't make any noticeable sound.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Your aftermarket radio should have color-coded wires which identifies power, ground, speakers, etc. most depaetment stores carry a radio harness adapter kit. This will connect to your radio's exact color coded wires, and will plug right in to your factory's wiring plug. And don't forget electrical tape.

You cannot wire through the jbl amps you need to go to the amp and can only wire in the speakers

sounds like you got a bad stereo. it happens. i've i had the same thing happen, but the volume went up instead of down. check all the wires and make SURE they are all hooked up right.