Rear shelf speakers do not work?

[carnut1947]

I have a 99 740 IL. It has DSP. All speakers except the rear 4 on the shelf work. I pulled the grilles off the cover and the speakers look fine. Is this an amp problem? My understanding is if the amp has failed I will get NO audio. Should I start at the shelf or the radio in the dash?

[Aitch]

Start where the failure is. Test with a multi-meter whether there is any signal getting to the speakers, either at the speaker connection under the speaker box, or on the output harness from the amp (not sure which would be easier to get to for you).

[ebida3]

Look at the amp if all are out.

I am on TAPATALK and don't know how to start a new discussion so I don't mean to highjack your thread.
My rear speakers intermitenly make a loud hum. It lasts for anywhere from a second to three seconds. Granted the speakers are bad I get that buzz at certain frequencies.
Any thoughts or is it the obvious. It just started although the buzzing has been for a while now.

Check engine light (CEL) means 'Cost Estimate Large'

[ebida3]

Look at the amp if all are out.

I am on TAPATALK and don't know how to start a new discussion so I don't mean to highjack your thread.
My rear speakers intermitenly make a loud hum. It lasts for anywhere from a second to three seconds. Granted the speakers are bad I get that buzz at certain frequencies.
Any thoughts or is it the obvious. It just started although the buzzing has been for a while now.

Check engine light (CEL) means 'Cost Estimate Large'

I forget to mention the speaker hum happen even when the system is off. Or at least the radio knob off. With OEM voice activation is the system ever really off?

Check engine light (CEL) means 'Cost Estimate Large'

[carnut1947]

Well.... I now know why the shelf speakers did not work. Each speaker had it's positive wire cut at the speaker. I repaired each wire and WHA LA! they work, but the 2 left ones hum? I'll change them eventually. One thing I did notice is I hear no difference DSP on or off? Should it get louder or just add more bass?

[ebida3]

That's why they were cut. All the speakers connect to DSP amp. If amp is bad, like I believe mine is, you get the hum from that bad channel.

Check engine light (CEL) means 'Cost Estimate Large'