I had recently upgraded my 2011 Fiestas front and rear speakers to the plug and play Focal sets. Although the sound quality was good, there simply wasn't enough power to drive the new speakers with the standard Ford head unit. My last car was a Mk1 Focus and i had an all round Alpine set up, including Sub and Amp. I also had an inline Alpine 4 x 45 rms amp which was plug and play with my old Alpine head unit and sat secured to the back of my glove box.

Got me thinking, could i had this inline amp to the Fiesta to give the audio a bit more umph! It has to be plug and play and not require butchering the existing car wiring, well after second attempt the answer is yes, and it now sounds awesome 😁

This is not a how to guide, but rather what i did and what is needed. If anyone wants to attempt the same, you will need some kind of wiring knowledge and i will try and help as best i can if needed.

Things you will need:

Inline Amp - Mine is an Alpine Head Unit Power Pack KTP-445A, which came with Alpine specific connectors which didn't help.

Parrot SOT T-Harness ISO Adaptor - My Fiesta is a 2011 model with the 24pin wiring plug, so the Connects2 CT10FD09 was what i used.

Basic wiring tools - Snips and wire strippers.

Solder Seal Wire Connectors - Amazing things, first time I ever used these.

Heat Gun & Accessories - To use with the above.

EMI Shielding Tap - Only required if you have an Aux connection, which is why i had to make a second attempt at this 🫣

Wiring Harness Cloth Tape - Only required to tidy up the wiring and make it look OEM, for the sake of £6 well worth it.

Access to Fiesta wiring diagrams - Users have kindly posted wiring diagrams on here for most Fiestas, so shouldn't be a problem.

 

First thing you have to do is identify what wires you have with your exsisting stereo. Mine is the 24 pin, non bluetooth/USB set up, it does have AUX but is basic.

  

I made a pin diagram and worked out which wire was which from the Fiesta wiring diagrams.

Next, cutting the connects2 (above) wiring harness in half, cutting off the brown and two small black connectors. Standard iso colours here so quite easy to work out which ones are which. You basically need to keep all the ones present in your existing Male Fiesta connector and do the same on the female connector. I cut down all the wires not required to the base to make things easier.

Should end up with with something like the above, make sure you have plenty of wire to play with on each connector. Notice the Brown wire in the centre, this is the Ground wire for the Aux connection, it will need covering with the EMI shielding from as close to the connector as you can get to about 1cm from the wire end for now.

The inline amp wiring, you will need to identify which set of cables connect to the stereo and which side goes to the loom (Very Important!). I then cut the end of each of the connectors off, around 4-5 inches incase i want to go back to original in the future. Also the inline amp will probably have loads of connectors which wont be required for this, i cut mine down so they were out of the way. I only needed the 8 speaker wires, Battery (perm), Battery (IGN), Earth and the remote turn on (Blue/white) which was connected with the Battery (IGN) wire to save wiring extra connections to fuse box.

You should end up with something like the above, maybe not with the old school paper diagrams 🤣 Now, once you have checked and double checked you have the correct wires and connectors identified its time to start heat gun soldering.

All wires (above) soldered that were going to the Amp. My wiring required me to not to connect 5 wires through the inline amp, they would need to be conected directly to each other from each of the harness connectors. These were the Aux (L+), Aux (R+), Aux Ground (Shielded), MS CAN (+) and MS CAN (-).

Close up of the Amazing solder seal connectors, so much easier and stronger than connector blocks or soldering wires directly 🤯You can see a bit of the shielding tape on the Aux Ground in the middle. I forgot to take photos in between this and finishing.... You need to repeat for the other connector and then solder wire the 5 remaining wires to directly to each other from each connector. Making sure you put some more EMI shielding tape over the join.

 

The finished loom all covered in wiring loom tape, looks OEM and well chuffed with the result.

Loom plugged into the amp and ready to fit and enjoy! 

 

 

Pin out key i made for my 2011 Fiesta and the wiring colour code for the Alpine amp.

 

Wires not used for the Alpine amp (x4), Phone, Illumination, Power Antenna and Parking Brake.