Ford ACM Amplifier Fault — Subwoofer Not Working | The Vehicle Check
Loss of subwoofer output from a Ford's premium audio system — treble and mid-range audio continuing normally while bass is completely absent — is a specific ACM amplifier failure mode. Higher specification Ford models are fitted with ACM units that include a dedicated low-frequency amplifier channel. When this subwoofer output stage fails, the front and rear speakers continue normally but all bass disappears. The Vehicle Check repairs Ford ACM subwoofer faults at component level.
Subwoofer Faults on Ford Premium Audio
The subwoofer output stage in the Ford ACM handles significantly higher current than the satellite speaker channels, making its output transistors more susceptible to thermal stress and degradation. Failure is often progressive — reduced bass output, then distorted bass, then complete silence on the low-frequency channel.
Ford models most commonly affected include S-Max with Sony audio, Galaxy premium audio, Mondeo with Blaupunkt or Sony, and Focus ST with the upgraded audio pack.
Component-Level Subwoofer Repair
We bench test the ACM with dedicated low-frequency audio signals, identify the failed output transistor or capacitor in the subwoofer stage and replace it with a correctly rated component. The unit is retested across the full bass frequency range before return.
We cover all Ford ACM variants with subwoofer outputs, including standalone subwoofer amplifier modules fitted to some higher specification Ford vehicles.
Post Your ACM to Us
Remove the ACM, package it carefully and post to our Enfield workshop. We return it repaired in 2 to 3 working days. Call 0203 489 2610.
Send Your Unit Today
The Vehicle Check | Unit 8 Solway Business Centre | Tysoe Street | Enfield | EN3 7PH
📞 0203 489 2610 | 📧 info@thevehiclecheck.co.uk
Nationwide mail-in postal service. All work covered by our repair warranty.