Where's the Bass???

[jlkwiththree]

This is a weird one that I can't find anything on this forum about - perhaps because I am using the wrong search terms. But the 03 with moons and tunes has no bass sound at all. Volume is still good, it just sounds horrible. I checked the under seat amp to make sure it was getting power, checked balance and fade to see if the condition was specific to a particular channel, and ran through speaker checks to see if it could make sound from another source, all fine.

Has anyone had this occur? Am I looking at a full system replacement or should I go after another used amp (I know where a working one is) to swap with mine to see if that fixes my issue?

[Derf]

Any history on the problem? Did it work, then just quit one day, or has it never worked? If you verified power into the amp, then you have two items to test, amp output and speakers. The rear door speaker feed from the head unit also sources the signal to the amp. If your rear speakers are working, then signal to feed the sub is present. Could be the two sub channels are out, connector to the sub box disconnected, or open wire in the sub magnet coil. Link to some pin outs to help determine location of problem, attachment at bottom of original post. Sub video will show connector on top of sub box that may have become unplugged.
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[jlkwiththree]

He is the history as it was told to me by my daughter:

All was working as well as the 11 year old system could - so it had bass. Then while out running errands she said it was fine when she got out of the car and wasn't when she returned. This was about 2 weeks ago. She did nothing to the settings that would have triggered a change, other than the system cycling on/off as she ran her errands.

So:

- I tested the front speakers to see if they had lost the ability to produce bass (hooked one of them up to an old head unit I had on my bench that I pulled from another car. It sounded normal although I did not push it as the head unit is for 4 ohm impedance.
- This car does not have the rear sub/subs, unless the rear door speakers are the subs. Nonetheless before this happened I know that I could fade to 100% front and get bass before this happened. The condition I am observing is an equal sound quality (no bass) regardless of balance/fade settings. All four door speakers are producing the same tinny sound.
- I checked and rechecked the connections and they seem to be good - no loose wires or contact points in the plugs. They also look very clean, both the pins on the amp and the connectors.

What I am suspecting is there is a channel in the amp that produces the bass that may be out.

I looked over your videos (very well done!) which did help me map out the wiring. But since I do not have a factory sub mine will be a bit different. I think my only answer may be a full system replacement. UGH!

[Derf]

Without the factory sub, the setup is slightly different. Your head unit should power the speakers directly. I believe the OEM GM Vibe head unit has buttons that allow you to digitally adjust the bass level confirming it with bars that appear on the clock/tuner display. Confirming that you are able to adjust the settings, I would say the frequency output of the head unit has failed. Replacing the head unit with another OEM unit (eBay?) or getting a head unit package online may be the best fix. If you are trying to save money, look in the descriptions for replacement head units that are 2 ohm stable. Those units will work best with the OEM Toyota speakers.

[jlkwiththree]

I tried adjusting sound quality (bass to the max and reduce treble to lowest level) and still no bass. This car does have the factory amp under the front passenger seat from which the speakers are fed. 2003 and 2004 models with Moons and Tunes pkg were only 6 speaker units. 2005 was the first year for the 7 speaker systems (added the rear sub). None the less I figured the 12 year old system was not worth fixing so crutchfield got a bunch of my money recently and now have all the pieces for a sound system overhaul. I will be posting what I did soon.