2007 Toyota Highlander Limited bass issue

[jbroses]

I bought a 2007 Highlander Limited (w/JBL sound system) a few months ago. Right away, I noticed that the bass would intermittently cut out (radio, CD, tape, everything). It'll cut out for a few seconds, come back in, cut out again, come back. I would say during a 20 minute drive, it usually happens 1-2 times (so you could drive around for 10 minutes and it might not happen at all). It doesn't seem to be related to battery drain (doesn't happen more when wipers are on or windows are rolled down, doesn't happen more when idling vs. driving).

I have an extended dealer warranty and brought it in to the dealership this past weekend, but they claimed after testing for 2 hours they couldn't reproduce the problem or find anything wrong with the stereo at all. Resigned to give up, I decided to live with it... until this morning, when I decided to see if the bass issue was limited to any one speaker. I decided to replicate the testing the dealership said they would do (testing each speaker zone individually by modifying the balance and fader).

Lo and behold, when faded all the way to the rear, the system produced NO BASS AT ALL. Like absolutely zero. (FYI - Both front speakers have the bass cutting in and out problem, neither one more than the other).

Any clues what the deal is here? This can't be normal, right? I'm definitely not a car audio expert, but the rear speakers are the ones that are SUPPOSED to be producing bass, right? I don't really care if the problems are related, but if replacing the amp will fix both problems, that would be great. It should all be covered by teh warranty. In any case, I want to call the dealer and yell at them for being idiots and not doing any testing, so I'd love to hear people's thoughts (to help give me some ammo).

Any help is appreciated. Thanks!

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[akheathen Premium Member]

what are the drivers in the system? i'm assuming the sub takes a summing of all the channels. perhaps it is dvc like the bose gm, and one of the coils is fried/shorting.... or pinched wiring, or the amp, or deck is bad.... they should be able to pull a "part-swap" to see if the hu is good...

 

[jbroses]

what are the drivers in the system? i'm assuming the sub takes a summing of all the channels. perhaps it is dvc like the bose gm, and one of the coils is fried/shorting.... or pinched wiring, or the amp, or deck is bad.... they should be able to pull a "part-swap" to see if the hu is good...

Oh, dear. Now it becomes obvious that I'm a newbie. I understood about 5 words in your reply, so I'll to my best to try to respond.

The guy at the service department said he thought my system had a subwoofer, but he couldn't find it (looked around in the back). But I'm not sure if it takes a "summing of all the channels."

I don't know what the drivers are, is there a way I could find out?

Is there any rational reason why when faded all the way to the rear there would be NO bass whatsoever? Would that in itself be an indication that something was wrong and they needed to fix something?

Thanks for your help, and sorry I'm so ignorant!

 

[akheathen Premium Member]

oh, lol...there is a stickie in the section that defines terms....... basically, a driver is a speaker/subwoofer, but used in different context, can also be reffered to describe an amplifier. so what i mean, is describe all the speakers, including sub(s) there should be 8 in the jbl premium, from what i could find. so, locations to look is, all 4 doors, the top of the dash, but the windshield, the bottom of the dash by the doors, the rear gate, the sides of the rear compartment, the rear pillars/roof, and the center console. on the center console, i have seen toyota put one at the rear bottom, firing back, but i have also seen some setups, like Bose, where it's hidden in the center console, basically under the dash. sorry that my Toyota experience is basically 10 years, or more older than what you have, but i also know that the tech working on it, should have no problem identifying all speakers, especially, since he should know to hit the Toyota tech docs on his computer...... worst case, you call Toyota directly, and/or go to another dealer and have someone who knows what they are doing figure it out. now, "summing" basically means that it takes signal from more than one channel and turns it int an average signal. it can sum 2 channels, or all 4. that is usually how factory systems work, with more than the 4 channels... so, go look around while it's playing music, and listen to all areas that look like there is a speaker and see if it's putting out. it is quite possible that either the sub amp, or sub(s) simply have a problem. try to figure out if it happens when you hit a bump, or are listening to a lot of bass. it would also be helpful to find another highlander to compare with. being under warranty, there is very little you are allowed to mess with that will not void the warranty, but the more information you can bring them about the problem, the better. also, if they have poor communication/listening skills, then a written explanation will be very helpful, and they can't cut you short "ok, we'll look at it" before getting all the info. when the tech gets kind of stumped, then he can read over the symptoms again...

 

[jbroses]

OK, thank you so much for your patience, I obviously should have looked at the FAQ first. Very good explanations.

So I checked it out, and I could only find 6-speakers: 1 speaker on each door, plus tweeters on each of the front doors. I found NOTHING underneath the center console, on the dash, the rear gate (or anywhere in the rear compartment at all). The problem is edmunds.com lists the Limited as having 8 total speakers (and I found some other sites listing 10 speakers). But then I found another site listing a 6-speaker package. Any way I can look up options by VIN#? Maybe the last 2/4 speakers aren't producing any sound, so I'm having trouble finding them? I'm assuming a subwoofer would be easy to find because of its physical size (even if it wasn't producing sound).

The problem doesn't seem to depend on hitting bumps at all (sometimes it happens while I'm stationary and idling). It also happens in both high bass (Zeppelin) and low bass (NPR) situations.

Here's what I did find:

- Faded to the front, everything sounds great. All 4 front speakers work perfectly, lots of bass response.

- Faded to the rear, there is VERY little bass (this is NOT an intermittent problem, it is constant). The Right rear speaker produces even less bass than the Left Rear (which produces a LITTLE bass). The change is just shocking and dramatic on fading from front to rear. The change from Right Rear to Left Rear is minor, but noticeable.

I talked to a manager at the service center, and they apologized and agreed to look at it again. My questions are:

- What can I tell them needs to be replaced? It would be much easier if I could say "it's either the wiring to the rear speakers, the head unit or the amp." Not knowing anything, I don't know how to narrow it down, and I fear the "we looked and couldn't find anything wrong" answer again. Does the fact that there are TWO very different problems here (bass intermittently cutting out and consistently reduced bass to both rear speakers) indicate it might be one thing over another?

- Can I insist they do a swap-and-test? Is that crazy, or do most shops do that?

- Any other advice?

Thanks again for all your help!

 

[Bumpin' Goalie 10+ year member]

If you have noticed a problem, it is their job to make that problem go away. So I'd feel brave enough to ask if they could do a part-swap (even just for testing). As far as finding the problem itself, it may be something internal to the headunit, or wiring. If this affects two speakers simultaneously I would like to think the speakers are fine. However, I have seen factory speakers/subs fail before.

Best wishes!