Amp Bypass Fail—Need Help!

[fredthegreat]

I just pulled out the factory amp from beneath my passenger seat and have wired up a new harness according to this website:

Stereo Wiring: Land Cruiser / LX 470 (1998-02)

Article by: RobRed Applicable Models: 1998 - 2002 / 100 Series Land Cruiser or Lx 470 Changing your head unit to an aftermarket unit is pretty stra

tlcfaq.com

I’ve identified all the speaker channels and separated them, and then also bridged the wires it says to under the “Landcruiser notes” section. The picture below is of all those things:

now what’s left are all these cables. I decided to just cut them out of the existing harness since I wasn’t using it anymore and just made sure they weren’t making contact with anything. I had tape covering the wires initially, but I removed that to show you all:

Here’s the issues:

1.) I tried to directly hook up the constant, ground, and accessory power up to my new radio’s harness just to make sure that it will turn on. When I twisted the wires together to make the connection and go to turn on my car, the radio does not start. However, the radio will start from its own power source that is in my house. This makes me think that the B+ in the first picture isn’t actually sending out power or that it’s not grounded.

2.) The digital display with the time/temperature, the recirculate/outside air button, the A/C button, and defrost buttons, and the rear control buttons light won’t come on. All of the buttons themselves function to do what they are meant to, but they don’t have any lights. The little digital display just doesn’t work at all.




Some notes:

-I figure the second issue is caused by me disconnecting the extra wires from the second photo from the harness. That somehow, it knocked out the lights for the HVAC controls. As for what made the constant go out (if that even is the case), I have no clue.

-I cannot find any diagrams online fully showing what every cable underneath this seat goes to. I am completely lost.

-I watched this YouTube video and planned to do what he did: make a new harness and just wire up all the speakers wires, constant, ground, and accessory, feed it into the radio den, and hook that up the the connector your aftermarket radio came with effectively making every other connection underneath that seat irrelevant (or so I thought).

-I left this brown wire with the screw connection intact and still screwed in.

-There is this little bit of wire just protruding from this sleeve. I have no idea what it is or what it does, but that’s what it looked like ( I did not cut off whatever it was going to).

Please, someone with experience help me. This has been an ongoing thing for 6 months and I’ve made no progress. I really just want to use my new radio!

 

[suprarx7nut]

I think you need a dmm. Then trace back 12v and ground from the various wires on the little display and your radio and figure out which one(s) are at fault.

I can send screenshots of the wiring diagrams if that helps.

What year?

For others reading: never cut wires from the factory harness unless you really have to. It can make life much harder down the road.

 

[Tanner H]

hmm I did the tlc bypass procedure and it works great. I'll level with you, I dont remember cutting all the wires like you did. It was a couple months ago, but I remember just a few were cut and spliced together to activate the bypass. In your defense, I believe I failed at my first attempt when I didnt get any power from the radio. Had to go over my work again to realize I missed an important splice.

I dont think I have time tonight, but most likely tomorrow i can pull my seat off and take detailed photos for you.

If you get too frustrated, you can always go to plan b and run new speaker wire to all four doors directly off the new head unit. You're essentially doing thaty anyway with the bypass procedure.

 

[krispykritter]

Your wiring looks amazingly like mine, which is from a 2006. Unfortunately, there are zero wiring diagrams that I was able to find that actually matched the wires in my LX470 with ML stereo.

That thick brown wire with the extra plain wire sticking out the the side is the original signal wires plus shield from the OEM radio to the OEM amplifier. Rather than running a + and a - for each signal, they ran a + for each signal and a shield for all of them (the way signal wires work is that one wire carries the actual signal, and the other is used to gather all noise along the path to be cancelled when the signal is amplified).

Those two sets of twisted blue wires are likely for your subwoofers in the trunk. Depending on if you have one or two subs determines if only one set or both sets of wires do anything.

Do you still have the OEM radio in the vehicle? I do, and when I did this job, the lights for the HVAC/clock/etc never went out. They worked the whole time, even with all the wires under the passenger seat removed. At a guess, they are somehow powered via the headunit.

I really hate to say this as someone who has recently struggled through this, but I'm not sure it's possible to remove the headunit from an 06+ and still have everything function. Can't even fully remove the amplifier because all the controls for the radio are actually in the amp, not the headunit.

As mentioned above - your only chance is a multimeter. Lots of the wires are just digital signals that would be sent to the OEM amp and can be discarded IF you can figure out how to get your radio working. No idea how your AC would function though, since the only way to change your vent configuration is through the headunit.

 

[archerwolf]

What year and make is your vehicle? And what's does your factory radio/ac control panel look like?

I did not see your vehicle description in your post...

For my 99 LC, the TLCFAQ instructions worked. I did not cut out any of the unused wires from the under passenger seat harness.

 

[4PF RIS]

hmm I did the tlc bypass procedure and it works great. I'll level with you, I dont remember cutting all the wires like you did. It was a couple months ago, but I remember just a few were cut and spliced together to activate the bypass. In your defense, I believe I failed at my first attempt when I didnt get any power from the radio. Had to go over my work again to realize I missed an important splice.

I dont think I have time tonight, but most likely tomorrow i can pull my seat off and take detailed photos for you.

If you get too frustrated, you can always go to plan b and run new speaker wire to all four doors directly off the new head unit. You're essentially doing thaty anyway with the bypass procedure.

I also have a 99 and am wanting to bypass my amp to install a new head unit. I uam having trouble finding out what harness/connector I need to buy since everything seems to be 2000-2007. I read through the tlcfaq walkthrough but did not see any specified connectors that would be required. Do you recall what you had to buy in order to bypass the amp?

 

[tahoejoe]

I also have a 99 and am wanting to bypass my amp to install a new head unit. I uam having trouble finding out what harness/connector I need to buy since everything seems to be 2000-2007. I read through the tlcfaq walkthrough but did not see any specified connectors that would be required. Do you recall what you had to buy in order to bypass the amp?

Short answer: No additional connectors are required to be purchased as long as you are willing to solder or crimp into the existing speakers wires.

I have 2001 LX, ML with aftermarket radio. I recently removed factory amp since it was not being used and cleaned up the previous installation and broken speaker wires to the doors.
After market head unit has after market speakers wires from head unit to area under passenger seat where spliced into factory speaker wires.

So.... briefly....
After market head unit speaker wires through floor/side to passenger side under seat.
Splice under passenger seat into factory speaker wires without removing existing factory connectors.

Driver side door speakers wires are pink/purple. I don't remember passenger side colors since they were working.

 

[ogsuv]

I think you need a dmm. Then trace back 12v and ground from the various wires on the little display and your radio and figure out which one(s) are at fault.

I can send screenshots of the wiring diagrams if that helps.

What year?

For others reading: never cut wires from the factory harness unless you really have to. It can make life much harder down the road.

Definitely this.

Regarding using a multimeter to check ignition and constant 12v at the radio location. A good old fashioned test light would also work **at your own risk

If I remember right from 9 years ago when I did this, once the amp is disconnected, one of those two wires at the dash area no longer has power. I ended up running a wire from the passenger seat area up to the dash area and all was well.

Annnnd I just noticed that the original post is 3 years old. lol.

maybe this will help someone else in the future.

 

[4PF RIS]

Short answer: No additional connectors are required to be purchased as long as you are willing to solder or crimp into the existing speakers wires.

I have 2001 LX, ML with aftermarket radio. I recently removed factory amp since it was not being used and cleaned up the previous installation and broken speaker wires to the doors.
After market head unit has after market speakers wires from head unit to area under passenger seat where spliced into factory speaker wires.

So.... briefly....
After market head unit speaker wires through floor/side to passenger side under seat.
Splice under passenger seat into factory speaker wires without removing existing factory connectors.

Driver side door speakers wires are pink/purple. I don't remember passenger side colors since they were working.

I would be willing to solder/crimp the existing wires. So all I would have to do is solder/crimp the new speaker wire from the head unit to the correct wire from the factory amp harness?

 

[tahoejoe]

I would be willing to solder/crimp the existing wires. So all I would have to do is solder/crimp the new speaker wire from the head unit to the correct wire from the factory amp harness?

Yes. Assuming your head unit comes with short speaker wires, you would crimp longer wires behind the head unit, run those speaker cables (4wires, L+/- R+/-) under the floor carpet to under the passenger seat. Then its up to you if you want to peel back insulation and solder or cut and join 3 wires together.