2018 Sync3 9 speaker system...learned something today

[15guardGT]

So I checked over the forum and found a wiring diagram showing the detailed wiring on the factory amp and what the wires coming into and out of the amplifier were and proceeded to do my own amplifier bypass on my 2018 ecoboost.

Well, after installing all new component speakers (minus the center dash, not using it at all anyway), adding a 5 channel amp and running all the wires...the dash no longer worked, the radio has a backlit dark screen (can only tell there is a backlight in the dark, otherwise the screen stays black). The car starts and runs fine, drives good sans the fact the instrument cluster and radio are dead.

So, I did some more digging on this forum, and while I did find a solution to the issue (only apparent after realizing the problem), I didn't find the problem. Turns out the factory amplifier (DSP) cannot be completely bypassed using the line in and speaker outs. The DSP is linked into the canbus and kills the canbus signal for the IPC, APIM, TCU and maybe another acronym or two if you completely disconnect it (all three connectors, primarily C2385A, which has the canbus hi/lo wiring (pins 15 (green) and 16 (white).

Also the line in stuff shown on the wiring diagram in the sticky doesn't match what my 2018 has after purchasing the motorcraftservice 72 hour subscription, as it only shows left and right audio outs, nothing for front and rear, just left and right.

The solution is to actually buy the t harness and fosgate dsp, which saves the canbus and keeps the factory wiring in place (bit late for me as I cut, solder and heat shrink every connection I made, so that'll be a fun mess to clean up)

Just thought this may be a bit of slightly useful information for those doing the factory amplifier (DSP) bypass on a 2018. I've certainly learned more about the canbus network than I planned on.

If anyone else has had this issue, or knows of a different cause or a different solution, I'm all ears. I will be reconnecting the canbus wiring first and going from there this weekend when I get a bit of time to get back on the car (has only been in the garage with no interior for a month).

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[GTthree50]

I have been working on my own adapter harnesses to do what you did without bypassing the factory amp. I bought the corresponding plugs from Molex and have speaker in and out separated from the amp to feed an external unit while leaving all other wires going to and from the factory amp in tact. Still not entirely certain if it will work but I’m hopi g it will but so far I don’t think anyone has accomplished this without a dedicated DSP. Having just recently learned about the Fosgate DSR1 and T Harness I think it is the way to go but apparently some users have had a very hard time downloading the can bus firmware and without a PC it cannot be updated. Only owning a Mac, this poses a small problem. I’ve already replaced my front speakers and disconnected the center channel so we are going down similar paths. I’m very interested to see how your system turns out. Best of luck!!

 

[rambunctious]

So it seems that you will loose the fade feature with an aftermarket amp since it must be sent as a command via CAN to the DPS for MY'18, instead of managed within the headunit of previous models?
not that fade adjustment is critical after you tune the system to your preference anyway ........

Ramb

 

[15guardGT]

Updating for information for others that may come across the issue I had in the first post.

I was finally able to get some free time to go through and finish the factory amplifier bypass successfully, and without the DSR1 (which I bought, still new in the plastic along with the matching harness). It turns out the wiring diagram in the sticky does match 2018 wiring as far as input and output channels go even though the factory service manual for the 18 doesn't show the same thing. This means that even without the DSR or equivalent, you maintain fade and balance ability after bypassing the factory amp.

My problem was in the canbus network the factory amp is tied into, and on my car, I ended up having to solder a 120ohm resistor in the circuit to restore communication to the dash, stereo and other components on the canbus 3 network..Your mileage may vary though, as I assisted a friend doing the same bypass on his 18 GT yesterday and no resistor was required to maintain network integrity.

A side note..I am usually very brand loyal when it comes to car audio (polk), but went with the Hertz speakers for the doors and tweeters based on the very tight fit of the 3.5" speakers. After getting the system working, I am very impressed with these speakers, Kudos to the other forum members who shared the information about Hertz and sizing.

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