Contact us
Close contact box

Metra 70-8121 Amp Bypass Harness

Allows you to install a new car stereo and bypass the factory amplifier in 2005-06 Toyota Tundra Extended Cab trucks with tweeters

Item # 120708121

This Metra 70-8121 amp bypass harness allows you to install a new car stereo in your car without having to cut the...

Find what Fits your car

This Metra 70-8121 amp bypass harness allows you to install a new car stereo in your car without having to cut the...

California customers:
Please click here for your Proposition 65 warning.

Need help?
Contact our Virginia-based experts.

Item # 120708121

In stock
$24.99
Add to wishlist

About the Metra 70-8121 Amp Bypass Harness

Metra 70-8121

This Metra 70-8121 amp bypass harness allows you to install a new car stereo in your car without having to cut the factory wiring, and to directly connect your new car stereo to the speakers in your truck.

Metra 70-8121

This Metra 70-8121 amp bypass harness allows you to install a new car stereo in your car without having to cut the factory wiring, and to directly connect your new car stereo to the speakers in your truck.

Simply splice the color-coded wires on your Crutchfield bypass harness to the wires from your aftermarket stereo — you can crimp or solder the connections in the comfort of your home without having to struggle with splicing wires behind your dash. Next, plug the Crutchfield bypass harness into the harness that you removed from your factory radio.

Since you didn't have to cut off your car's original radio connector, it's easier to put the factory radio back in when you sell your vehicle or return it at the end of the lease. Just plug the factory radio back in and keep the aftermarket stereo. Warranty: 1 year.

Important Note: This harness bypasses your factory amplifier. In order to install it and make the necessary connections, you will need to run wires from the harness to your factory amp location under the right rear seat. 

Please enter your vehicle information or call a Sales Advisor at 1-888-955-6000 to find out if this model is compatible with your vehicle.

READ LESS

What's in the box:

  • 8" Power/ground harness
  • 17' Amp bypass harness
  • Installation Instructions
MFR #70-8121

Customer reviews

Loading reviews...

Metra 70-8121 Amp Bypass Harness reviews

Average review:

9 reviews

Filter by rating

Customer photos

Sort reviews

Sort by:
Items per page:
View page:

Metra 70-8121 Amp Bypass Harness

Crutchfield customer from Marana, AZ on 7/1/2019

2006 Toyota Tundra

Verified customer (What's this?)
Verified employee purchase (What's this?)

Harness worked well and was easy to installkiki

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Easy non JBL amp bipass

Crutchfield customer from Hatfield, MA on 6/23/2019

2005 Toyota Tundra

Verified customer (What's this?)
Verified employee purchase (What's this?)

Everything needed to bypass factory Panasonic amp. You unplug speaker Connector from amp and Plug fits right into that connector..instructions were clear and included. Quality wire and connector. My new system sounds great!

Pros: Easy plug in

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 70-8121 Amp Bypass Harness

Crutchfield customer from Grass Valley, CA on 5/15/2019

2006 Toyota Tundra

Verified customer (What's this?)
Verified employee purchase (What's this?)

Very easy to install, it did what I needed it to do, solder a few wires, it by passed the amp, plug and play!

Pros: Great harness to bypass the amp.

Cons: None

Crutchfield response on

0 of 0 found this helpful

Worked great!

Crutchfield customer from Tallahassee, FL on 4/29/2019

Verified customer (What's this?)
Verified employee purchase (What's this?)

Worked great!

Pros: Perfect!

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 70-8121 Amp Bypass Harness

Crutchfield customer from Sunland, CA on 3/3/2019

2006 Toyota Tundra

Verified customer (What's this?)
Verified employee purchase (What's this?)

06 tundra with amp under back seat fit perfectly easy to install great product

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

2005 tundra non jbl amp under rear seat great harnesss

Robert from Grass valley, Ca on 1/11/2019

2005 Toyota Tundra

Verified customer (What's this?)
Verified employee purchase (What's this?)

Best harness ever! Struggling with this upgrade for days. 2005/06 Toyota Tundra extended cab 4 door (two small suicide doors)(Non-JBL) with door tweeters and the amp under the rear passenger seat (under black plastic cover in some cases) Two local car stereo places said it wasn't possible. It was, with this great product. Thanks. Highly recommend.

Pros: works

Cons: None

Crutchfield response on

0 of 0 found this helpful

Metra 70-8121 Amp Bypass Harness

Jim from Akron, OH on 9/20/2018

2006 Toyota Tundra

Verified customer (What's this?)
Verified employee purchase (What's this?)

Amazing customer service. I went to a local store that installs radios and they couldn't figure out the correct harness for my truck. Within 5 minutes of talking to a Crutchfield technician, I had the right part and had it ordered. Part arrived quickly and the new radio is in and sounding great!

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 70-8121 Amp Bypass Harness

Jerry from La Habra, CA on 4/9/2018

Verified customer (What's this?)
Verified employee purchase (What's this?)

2005 Tundra non JBL. Work well except the acc. wire was not hot on the factory harness. I just brought it up from the cigarette lighter and it worked fine.

Pros:

Cons:

Crutchfield response on 5/14/2018
Sorry for the accessory power dilemma, Jerry. On this vehicle, however, the wiring from the factory receiver/climate control trim panel must be reconnected when installing a new car stereo. This connection contains the accessory power needed for the new stereo. It's mentioned in step 8 of our exclusive MasterSheet instructions for the Tundra.

3 of 3 found this helpful

Metra 70-8121 Amp Bypass

Crutchfield customer from USA on 12/18/2017

2005 Toyota Tundra

Verified customer (What's this?)
Verified employee purchase (What's this?)

Long overdue item no doubt about it..Thank you Metra for supplying easy use equipment nobody else offers us "again". Bought this 2005 Tundra Access (extended) cab and this was the perfect solution to bypass my factory Toyota amp (Pioneer sticker on amp). NON-JBL UNIT ONLY...NOT 4 JBL.. Shame Pioneer/Toyota forgot to add any watts and speakers only 6" to the amp, you would think it would have power behind the 6 stack cd player they put in it too? Nope!! This system was a huge waste of time to even build imho and Toyota should be ashamed of it. Simply unplug oem "output" speaker plug from amp, snap this into the output harness itself and wire it back to receiver, done! I blame Toyota & Pioneer both due to what I know.. Pioneer has always been like burger king as they build exactly whatever a company asked for and still slap their name on it somewhere.

Pros: easy, simply unplug output from amp, snap this into output harness and wire it to receiver, done! I Removed old amp under rear seat. Long enough to reach back wall in crew cab 4 doors I had a few feet extra. For non-JBL units..

Cons: Hard to locate this harness. Not on Merta website to date?

Crutchfield response on

2 of 3 found this helpful

Verified customer (What's this?)
Verified employee purchase (What's this?)

Pros:

Cons:

Crutchfield response

<< >>

More details on the Metra 70-8121 Amp Bypass Harness

Stacey B.

Product Research

Features

Amp Bypass Harness: The Metra 70-8121 Power/Amp Bypass Harness consists of a 8" power/ground harness and 17' amp bypass harness. The 70-8121 is needed to bypass the factory amplifier in select 2005-2006 Toyota Tundra trucks, when replacing the factory radio with an aftermarket head unit.

Note: Installation tools, hardware, & accessories are not included & sold separately. Please see the Accessories tab for recommendations & availability. If your vehicle is equipped with factory steering wheel controls, an additional adapter is required & sold separately.

Wire Code Chart:

Power/Ground Harness
Wire Color Function
Red +12 Volt Accessory
Yellow +12 Volt Constant
Black Chassis Ground
Orange Illumination
Blue Power Antenna

 

Amp Bypass Harness
Wire Color Function
White Left Front Speaker (+)
White/Black Left Front Speaker (-)
Gray Right Front Speaker (+)
Gray/Black Right Front Speaker (-)
Green Left Rear Speaker (+)
Green/Black Left Rear Speaker (-)
Purple Right Rear Speaker (+)
Purple/Black Right Rear Speaker (-)

 

Loading accessories...

Customer Q&A

Q
Crutchfield asked: Why did you buy this?
A
Helping son with new radio [ James  Jan 01, 2019 ]
A
Needed for bypassing O E factory amp. [ Michael  Sep 21, 2018 ]
A
I bought a Pioneer AVH-4100NEX for my 2005 Tundra a couple of years ago and Crutchfield bundled it with an Axxess TYTO-01 Wiring Interface, which didn't allow the rear speakers to work. I really think they should have sent this to me for free. [ Robert  May 30, 2018 ]
A
It was the only option that fit my scenario. [ john  Mar 31, 2018 ]

1 question already asked

Q
I bought this but my amp has two plugs. What do I do with the other one?
[ Jerry  Apr 05, 2018 ]
4 answers
A
It does nothing it's not plugged into anything.
[ Ryan  Apr 25, 2018 ]
A
The Metra 70-8121 adapter is made to adapt an aftermarket head unit to the existing speakers without cutting the stock wiring harness. In order to do this, the existing Toyota amp is bypassed and the two amp plugs are not used. This adapter does not work if you want to use the Toyota amp. I installed a new more powerful Zapco amp thinking this adapter would work from my existing head unit and to my surprise it is not made for this application. I had to tap into the Toyota amp speaker outputs and wire it to an Audio Control line output converter, then wire the converter to the new amp and the new amp to the speakers. Sounds great!
[ DANIEL  Apr 24, 2018 ]
A
On my 2006 Tundra, I just left the other plug plugged in to where it was, I think. Works fine.
[ Theodore  Apr 23, 2018 ]
A
It doesn't go to the amp, it bypasses it. You unplug the amp, remove it, and just plug into the speaker harness that was plugged into the factory amp.
[ DaveH  Apr 23, 2018 ]

Loading articles...

TOP