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Speaker problems

The rear speakers in my 2000 Blazer LS have stopped working. There are no cut wires. (Factory stereo.) I have tried changing the speakers. And I found out today that another persons rear speakers are not working on their 2001 Blazer LS. Does anyone know of a common problem or perhaps an easy solution? Thank you.

might be inside the radio itself

The solution is probably to replace the head unit, which is the second most common cause of speakers not working right behind the speakers themselves being bad. If your current speakers have been verified good (it’s easy enough to attach them to some other audio source to see if sound is produced), the rear channels for the amp in the head unit have probably died.

I took the head unit out and not only tried another GM stereo, but a definate working after market unit in. Speakers still do not work.

If you know the radio is good and the speakers are good then the only thing left is the speaker wires. A volt ohmmeter will check them out in short order. Make sure they are disconnected from the speakers and radio before they are checked.

Is it factory wiring? I have seen bad splice jobs where the used electrical tape to cover the wires and they shorted out. Electrical tape is not for cars!

Since you replaced the head end unit and still get the same problem it sounds like (no pun intended) there may be an external amp to drive the speakers and the trouble is with the amp. Use an ohmmter to see if the speaker leads are shorted together or to ground. Remove the speaker and check the leads using the meter.

Rear amp controls left and right speakers. It could be bad or the fuse for it could be blown.

This model (LS) doesn’t have the external amp like my LT model. I can’t seem to find any cut or spliced wires. I guess the ohmmeter is my next step. I still welcome any other thoughts if anyone has them. Thank you!

What if you took a known good test speaker and temporarily connected it to the speaker wires in back? If you got sound, you’d know the wiring is good and the existing speaker is bad. Or if you get no sound, you know there’s no audio signal to the speaker, and the existing speaker is probably good and the problem is upstream somewhere. If so, you can move your test speaker upstream until you find a place where on one side it works, but on the other it doesn’t.

One caution in all this: Sometimes an audio amp will fail in a way that puts a voltage on the speaker output. This is very bad. It will usually burn out the speaker straight away, as soon as the amp is turned on. And if you thought the speaker went bad, put a new speaker there, turning on the amp will burn the new speaker out. If you think this may be happening, best to have a pro take a look before installing any more new speakers.

I have already tried a known working speaker and two known working stereos. I have all but pulled the carpet and mouldings to check every inch of wire from the harness back to the speakers. I’ve installed enough stereo systems in my time that if I need to I will run my own wires. But would rather leave it with the factory wires. (For time sake)

Yes, you need to check the continuity of the speaker wires end to end. Since you have already determined a working head end still has the same trouble and are sure there isn’t an external amp going to the speakers there can only be a couple of possibilites for the trouble. The wires have a break in them or they are shorted (not likely). Check for shorts to ground on the wires also

Are there any place(s) where the wires get flexed? Like if they go to a door or tailgate? If so, that’s the first place to expect them to break. Wires can look intact if you just look at the insulation, but still be broken inside the insulation. To find out where the break is, you have to narrow it down by testing the continuity of the wire in segments. The quickest method, requiring the fewests tests, is the so-called “binary search”.

If you want to get fancy, there’s a gadget that can determine at what distance along the wire it is broken. It sends a signal down the wire, then times how long it takes for the reflection to occur. Seems a tad bit of overkill for your problem, but if you happened to have access to one, it would tell you straight away how many feet down the wire the break is. Best of luck.

So I purchased a volt/ohm meter. And there is current going through the wires… Still rather puzzled on this one.

A VOM is a good tool to have. So you measure current in the wires going to the rear speakers, but no sound? I assume you mean you measured the voltage at the speaker terminals then? (To measure current you have to mechanically interrupt the circuit and place the meter in series.) Have you tried disconnecting the existing speakers and hooking up a replacement speaker as a test? Might be the rear speakers are just kaput for some reason. After all, if there is a signal going to them and you measure an appreciable AC voltage (like 1 volt rms or so) across the two leads, it seems like they should make some kind of sound.

Another test you could try after disconnecting the rear speakers and the test speaker doesn’t sound, is to see if you can connect the test speaker right where the signal comes out of the amplifier. Are you able to identify a place (probably under the dashboard) you can do that?

One caution, there is a failure mode in audio amps where the speaker output, instead of being around 0 volts with no signal, goes to 10 or 12 volts DC. When this happens, it will burn out any speaker you connect to it. So use your DVM to make sure this isn’t happening before connecting any test speakers, esp if they are expensive. Best of luck.