Ive recently started to drive my wifes car around, and only 1 of her 4 speakers are working. "she obviously didnt have a problem with this"

Where should i start to figure out the problem?

The speakers seem to be wired up to an amp which is under the passenger seat "i havent pulled the head unit out so i could be mistaken.
The only speaker that is currently working is the drivers front, the others dont work.

Im not sure if its the speakers/ amp or headunit?
Whats my best course of action?

Firstly, as strage as it sounds, check the balance and fader are set correctly....
More coming, I'll edit it in...

Assuming its been wired correctly, and all for a wired to to a 4 channel amp? - Testing is made easier as you have one working speaker....

After the fader/balance check, I'd check all connections, they could be loose, kicked, stretched or damaged ( or tampered with i.e. Gains are off etc ). Speaker wires at the amp & speakers, RCA connections amp and Head unit.. Power at the Amp (Indicating Power Light)

If they are all good, using the front right speaker wires ( assuming it is a 4 channel) connect that pair to each speaker output connection pairs on the amp, this will tell you if the amps for the other channels are working...
Then connect the other speaker wires, one at time, to the front channel that works, this will tell you if the speakers are not working.. If they fail, check the connections at the speaker. If the speakers wont work when connected to the working channel, fault check each speaker to see if its really finished...



If all the speakers work when connected to working channel, you'll need to check each amp channel and RCA, RCA's are easiest, so them first, take the front right RCA ( found by removing one at a time until it stops ) connect that (known to be working) RCA to each other RCA input on the amp, if all the speakers make sound this will show a fault in the amp itself....If they all work when connected to the front right RCA, then its time to check the RCA's - that at the head unit...
Connect the front right RCA out ( at the head unit ) to each speaker/channel RCA... Noise should be heard att all speakers when tested one at a time. That's front right RCA out to all RCA's running to the amp..
If this fails, its the RCA leads.. ( This is a likely problem).. If each speaker worked when tested, and each amp channel worked, and each RCA worked, its the headunit, then check the fader/balance again...

Hope this Helps...
Marty

Thanks for the detailed reply.
The first thing i did was check the fade and balance, which were all fine.
Ill do some investigation work and let you know the outcome.

Thanks for the detailed reply.
The first thing i did was check the fade and balance, which were all fine.
Ill do some investigation work and let you know the outcome.

No problem...Good luck...