4" to 8" Swap but volume button or knob doesn't work? Try this fix.

[puelloj]

Hey y'all. I have a Base 19 GT with the 4" screen (301a). I just recently put in an 8"screen from another 19 GT. The swap was super easy and almost everything worked except the volume buttons on the steering wheel and the volume knob did nothing. The radio and Bluetooth connections had audio that worked but stayed at the same level.

When I did the swap I replaced the ACM, FCIM and APIM with the new one. I could've probably kept my factory ACM, the square metal box, in there since it's practically the same minus XM radio but this new one had a CD player so I decided to swap it as well.

At first I thought it was my steering wheel controls/module was faulty but the mute, forward and back buttons work except volume +,-. But I also assumed it couldn't be the steering wheel controls because if I click mute and press volume it would un-mute so it was registering an input but just not changing anything

I went on Forscan. Took a peek at the FSIM AND APIM to see if there was anything I needed to change other than the VIN. But nothing about volume controls appeared.

So I figured it had to be an issue with the actual radio/audio module. Then I decided to mess with the ACM. I found a database of as-build data on cyanlabs(dot)net. It seems like these were edited by F150 guys but it's practically the same technology and software.

Found the corresponding ACM database and found this.

Front/Rear Satellite Speakers
727-01-01: xx*x-xxxx-xxxx

Values
0=Front: Int Amp, Rear: Int Amp
1=Front: Int Amp, Rear: External Variable
2=Front: Int Amp, Rear: Fixed L/L
3=Front: Int Amp, Rear: Not Used
4=Front: External Variable, Rear: Int Amp
5=Front: External Variable, Rear: External Variable
6=Front: External Variable, Rear: Fixed L/L
7=Front: External Variable, Rear: Not Used
8=Front: Fixed Line Level, Rear: Int Amp
9=Front: Fixed Line Level, Rear: External Variable
A=Front: Fixed Line Level, Rear: Fixed L/L
B=Front: Fixed Line Level, Rear: Not Used
C=Front: Reserved, Rear: Int Amp
D=Front: Reserved, Rear: External Variable
E=Front: Reserved, Rear: Fixed L/L
F=Front: Reserved, Rear: Not Used
Notes
Int Amp=Default
External Variable=4 Volts (Vref1)
Fixed L/L=aka Smart Amp


My line was set to xxBx-xxxx-xxxx
Since I have a base model GT, I assumed I don't have any "fancy" amps I changed my value to xx3x-xxxx-xxxx.

Then clicked "write all", cycled the ignition button and BOOM, volume works now.
It seems like the Kit I got probably came from a Mustang with a sub in the rear or the higher trim audio package.



Thanks for ready.

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[Cathul]

Values
0=Front: Int Amp, Rear: Int Amp
1=Front: Int Amp, Rear: External Variable
2=Front: Int Amp, Rear: Fixed L/L
3=Front: Int Amp, Rear: Not Used
4=Front: External Variable, Rear: Int Amp
5=Front: External Variable, Rear: External Variable
6=Front: External Variable, Rear: Fixed L/L
7=Front: External Variable, Rear: Not Used
8=Front: Fixed Line Level, Rear: Int Amp
9=Front: Fixed Line Level, Rear: External Variable
A=Front: Fixed Line Level, Rear: Fixed L/L
B=Front: Fixed Line Level, Rear: Not Used
C=Front: Reserved, Rear: Int Amp
D=Front: Reserved, Rear: External Variable
E=Front: Reserved, Rear: Fixed L/L
F=Front: Reserved, Rear: Not Used
Notes
Int Amp=Default
External Variable=4 Volts (Vref1)
Fixed L/L=aka Smart Amp


My line was set to xxBx-xxxx-xxxx
Since I have a base model GT, I assumed I don't have any "fancy" amps I changed my value to xx3x-xxxx-xxxx.

Then clicked "write all", cycled the ignition button and BOOM, volume works now.
It seems like the Kit I got probably came from a Mustang with a sub in the rear or the higher trim audio package.

Your kit came from a Ford with Sony system, not from any Mustang.
Sony (and B&O) systems have fixed line level output. Volume control is done via CAN bus messages in the amplifier in these systems, and not in the ACM.

 

[puelloj]

Your kit came from a Ford with Sony system, not from any Mustang.
Sony (and B&O) systems have fixed line level output. Volume control is done via CAN bus messages in the amplifier in these systems, and not in the ACM.

I got the parts from leecparts who sell parts from salvaged cars so I wasn't sure what mustang build these parts came from. I wanted to post this for those who might deal with same I did. It took me a bit to know which lines to edit and find the information. I don't think this forums has this ACM build data.

 

[Cathul]

It has, but the information is scattered through different threads.
Anyway, I really like if people share information they found out themselves, so kudos to you.

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