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03 Highlander Ltd - Replace Factory Head Unit Questions

2445 Views 5 Replies 3 Participants Last post by  sweeneyp
Hello. I just bought an 03 Highlander Ltd and want to replace the factory stereo. I know this has been asked in various forms and I have researched but not found the answers I am looking for.

The speakers (6 total) say JBL on them, but the head unit does not. I would like to keep the speakers for now and upgrade only the head unit, but do not know if the front speakers (with separate tweeters) use a passive crossover or if their individual signals come from the amplifier/head unit and would therefore require a more complicated solution. I will call crutchfield tomorrow but wanted to post here as well. I was hoping to simply bypass the stock external amp (if there is one) and power the speakers with the new head unit as long as the tweeters would work (in other words if they use a passive crossover). Unless, the stock external amp (again, if there is one) is of decent quality and it is the factory head unit that is primarily ruining the sound.

The crutchfield site recommends an adapter which sends the head unit signal to the original amplifier at line level, but I don't know the quality of that amp or if the onboard amp of the aftermarket head unit (20W RMS @1% THD) would be superior. I do know that even a little turn of the volume knob totally thins out the sound. Is the head unit doing this to manage power or is the amp somehow contouring the signal because it can't handle the increased output demands of bass frequencies as the volume increases? I hope that makes sense. I appreciate any help or links to previous threads I may have missed.
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It should be passive, the headunit only outputs 4 channels (as does the amp). The JBL system is an 8 speaker system (rear coxials count as 2 each).

The headunit is probably what is applying the OEM EQ to the system you are complaining about. A new headunit might help with that. One thing about the power. You likely won't get 20watts out of an aftermarket unit. Usually its closer to 15 a full tilt. Look at the CEA certification not the manufacturers rating. For example, Pioneer lists their units at 20 watts, but they are rated at (under CEA's testings) 14 watts. Having said that, the OEM amp is probably 20-25 watts each channel.

I personally would try to keep the OEM amp.If you want to bypass it, you will likely have to run new speaker wire to the headunit.
 

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Discussion Starter · #3 ·
Ok. The JVC head unit I am looking at is certified rated at 20wrms and I know in the past that I have been pretty much satisfied with the power from a given aftermarket head unit (running power from the battery for an external amp is a pain). I agree that the factory receiver is probably responsible for the evaporation of bass as the volume goes up...almost like an attempt to protect people from themselves when they try to turn it up. The amp probably isn't "smart" enough to do that. Anyway, I guess I need to decide how difficult it would be to run speaker wires. Probably more than I want to do right now.

Also, where is the amp? It is easily accessible? Could I use the power leads for it and simply swap a small aftermarket external amp in its place? I could probably handle running rca cables if the power lead was sufficient for an aftermarket amp. Thanks for the information.
 

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If it's like my 06 non navi jbl system you will need a head unit with 4 outputs. 2 right, 2left. The amp is in the back near the bumper. If you choose to bypass the amp you have run wiring back to that amp.
 

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Discussion Starter · #5 ·
Actually, I would rather simply bypass the amp and run the factory speakers off of the new head unit. But there seems to be some question as to whether or not I would have to run new wire to the speakers (which I don't want to do) or if there is a bypass harness behind the unit (mentioned in another thread). Can anyone confirm or must I remove the factory unit to check? Also, I have a tool to remove a single din unit, will that work or is there a special tool for the 2din Toyota units?
 
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