S550 Electronic Modules and Their Networks -- A Primer

[Skye]

I've been reading up on the main electronic modules and internal networks of the S550. Attached are my notes. If you don't know a LIN from a MRCM , they might help.

----------------------Revision History----------------------------
01 January 2026. Charging System Document UPDATED.

06 August 2025: Active Anti-Theft, Intelligent Access, Passive Anti-Theft, TPMS -- ADDED

09 July 2025: Link of video identifying module locations, -- ADDED

08 July 2025: "Primer" documents with web site appendices have had those appendices UPDATED.

17 June 2025: Flushing the S550 Brake System -- ADDED.

10 June 2025: S550 Mustang Cooling System -- A Primer, ADDED.

05 June 2025: Cooling fan schematics, ADDED.

29 December 2024: Supplemental Restraint System document UPDATED.

26 December 2024: OBD Systems Operations UPDATED.
26 December 2024: Sync System document UPDATED.
26 December 2024: Modules and Nets document UPDATED.
26 December 2024: Charging System document ADDED. Later UPDATED. See 01 Jan 2026 post.

02 October 2024: Connector pigtail reference, 2016, ADDED.
02 October 2024: Connector pigtail reference, 2018, ADDED.
02 October 2024: Connectors, were used, 2020, updated by Ford in '23, ADDED.

15 August 2024: Ford OBD Systems and Operations added.Consolidated 26 Dec 24.
15 August 2024: Ford OBD Operations, Malfunction Parameters added. Consolidated 26 Dec 24.
15 August 2024: Self-made file of Mustang DTC codes ADDED.
15 August 2024: A simple explanation of Electronic Power-Assisted Steering ADDED.

28 June 2024: Modules and Nets document updated UPDATED 26 Dec 24.
28 June 2024: Sync System document added. UPDATED 26 Dec 24.
28 June 2024: Supplemental Restrain System document added. UPDATED 29 Dec 24.
28 June 2024: Schematics, 2015-2017, ADDED.

13 February 2024: Modules and Nets document added. UPDATED 26 Dec 24.

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[Mike Pfeifer]

Nice! Downloaded that for future reference. Thanks!

 

[Cobra Jet]

Thanks Skye - very good info!!

 

[GTP]

Gets my vote for a living document and sticky.

 

[Cobra Jet]

Gets my vote for a living document and sticky.

Agree. I’d say definitely a sticky up in the Infotainment/Electronics sub-forum.

 

[Skye]

Several years ago, @Bull Run authored a thread, detailing a self-install of the Blind Spot Information System. As part of that thread, he included the attached: a book, 121 pages, of S550 schematics.

***The following schematics support the 2015-2017 Model Years. In 2018, there was a refresh to the S550 involving several major components. If you own one of the earlier MYs, enjoy. If you own a 2018 or later, you should exercise caution if referencing these.***

 

[Skye]

Posting some insight into Ford's On-Board Diagnostics theory and operation, picked up from the following thread: https://www.mustang6g.com/forums/th...ction-would-be-very-appreciated.204605/page-2

The link below will take you to a Ford Technician site, which lists OBD and other t-shooting documents:

https://www.fordtechservice.dealerc...asp?pageid=diagnostic_theory&gutsid=diagsheet

One file that explains how the OBD system works for many key features is here: https://www.fordservicecontent.com/Ford_Content/catalog/motorcraft/OBDSM1900.pdf . The file (15M) is too large to attach to this post.

Another document I found this morning at that same site lists the malfunction parameters for many key diagnostic codes, what will cause a code to trip and display: https://www.fordservicecontent.com/Ford_Content/catalog/motorcraft/OBD_System_Operation_Update.pdf .

To compliment all that, I'm attaching a PDF file of DTC codes I'd made earlier.

Thank You @Mach1Kid96

 

[Skye]

A simple explanation of Electronic Power-Assisted Steering (EPAS).

Edit,

Updating this post with two photos.

The first photo shows what a working belt and rack assembly look like. Notice the linear screw, for more precise steering.

The second photo highlights an entire EPAS assembly. To the far right, where the steering linkage connects. Center, the EPAS motor. Left, the belt attachment.

If the belt or motor fails, there is a fail safe mode, where the rack will continue to work, in manual mode.

 

[Skye]

Attached is a reference for Ford pigtail connector kits, 2016.

 

[Skye]

Attached is a reference for Ford pigtail connector kits, 2018. As the 6G arrived in 2015, and refreshed in 2018. Between the 2016 (above) and 2018 (here) reference, something might have been dropped or later added.

 

[Skye]

Attached is a reference, all Ford models I believe, of where any of these connectors can be used; it was published in 2020 and last updated in 2023.

 

[Skye]

Attached is a primer explaining batteries, alternators, charging and power load-shedding strategies.

Edit,

11 Dec 2025. I'm happy with the attached document, but I will be updating it. There's some additional information I want to insert into the existing attachment. Can't give a timeline. Will update this post again when I do.

12 Dec 25. While I cover lead acid and lithium batteries in the attached, I do not have narrative on Absorbent Glass Mat (AGM) types. Something to pay attention to in-particular: when changing from a traditional Flooded Lead Acid to AGM, the Body Control Module as-built data needs to be updated. The following thread has several posts about that.

https://www.mustang6g.com/forums/threads/battery-saver-message-on-a-new-battery.224209/

01 Jan 26. See new post. I've attached the updated document there.

 

[Skye]

Attached is an update to the original Modules and Nets document. It's a housekeeping update. Cleaned up some of the images. Updated Acronyms and Links list. The guts of the document remain unchanged.

 

[Skye]

Attached is an updated version of the original Ford Sync primer. This one has an updated acronym and links list. The rest of the original document remains unchanged.

 

[Skye]

Attached is the most recent OBD Systems and Test Document posted by Ford.

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