Sync 4 Retrofit...SiriusXM only works after APIM as-built rewrite, not on cold start

Ford AsBuilt
, , ,
1

Hi all,

I’ve done a Sync 4 retrofit on my 2020 F-450 (built December 2019) using a kit from fordsync4.com. The only new module is the APIM everything else is original to the truck. By all means everything else is working very well!

Modules:

  • APIM: RU5T-14G670-AGN (Sync 4, from kit)

  • ACM: LC3T-18K810-FE (original 2020 Super Duty)

  • GWM: LC3T-14F642-AC (original as wel)

The problem: SiriusXM shows “loading” on cold start and never resolves. If I connect FORScan and rewrite the APIM as-built (no changes at all, just a rewrite), XM works immediately and stays working until the next cold start. Volume also starts at 0 on every cold start which makes me thing its a timing issue.

What I’ve tried:

  • ACM 727-01-01 first nibble changed from 2 to 3

  • APIM 7D0-01-01 first byte changed from A0 to A2 (enable SDARS missing message logging)

  • APIM X40 XRP flag is already set to X40 (A8 in 7D0-02-03)

  • FCIM VIN corrected to match truck VIN - it was not the correct VIN at first.

None of the above fixed the cold start issue. The rewrite-to-fix behavior strongly suggests to me that a boot timing race condition between the Sync 4 APIM (faster boot) and the original ACM. (I’m a web developer though, not a systems developer for OEMs haha)

Any ideas appreciated - particularly around GWM sequencing or any other as-built flag that controls APIM retry behavior for the ACM handshake. Oh, once it works with that “fix”, EVERY channel works fine so I think the X40 is capable on my ACM and such

Thanks in advance!

2

In 2019 Ford transitioned from SiriusXM to the newer Sirius XM X40 to provide more native content and abandon the old Sirius transmission platform. Since you ACM is an LC3T-18K810-FE, it should comply with the changes. It kind of does seem like the ACM is not syncronizing with the APIM properly on cold boot.

Have you messaged the FordSync4.com folks and asked them about this behavior, and if so, what did they say?

3

Thanks for the response.

I did message them. They thanked me for the information. I asked if they had any further thoughts on if we could make it work since I do know it is working in some manner. Their reply again was thanks for the suggestion.

So I’m hopeful they’re working on it but nothing definitive yet. I’ve seen the crazy posts in here where you folks figure out some awesome stuff, so thought in the meantime why not ask and/or have someone way smarter than me tell me I’m way off track :joy:.