Odd speaker issue, bad head unit?

[MarnelKelis]

On my 1991 318is with the stock radio, only the back left speaker worked. I bought four new jbl 521f to install, as my car doesn’t have premium sound. Even after replacing all 4 speakers, the speaker locations that didn’t work before still don’t work. All the speaker connections are in good order, and all the associated fuses are good. Am I correct to assume this is an issue with the connection at the head unit or an issue with the head unit? I plan on pulling the head unit tomorrow to check. Thanks!

[martauto]

Welcome to the zone mate and we cant answer any questions until we see some/alot of pics of the 318is lol.
Mart.

[Satan]

Have you checked the cables to the HU are connected to the HU loom as with a lot of these cars a stereo install is one of the things on the Bodged list.