SPN 925 FMI 5 optimized idle weirdness

Symptoms: check engine light on, optimized idle doesn't work. Dd15 on '14 cascadia.

According to my research this code means open circuit on pin 17 connector 3 of the CPC. This wire allegedly goes to something called "optimized idle alarm". What is this optimized idle alarm? Is it the flashing optimized idle indicator on the dash? The hood open switch? Or something entirely different? Kind of hit a wall on my research without having to buy expensive and confusing manuals.

Any help would be appreciated. Don't want to drag my truck to Freightliner over this little issue and waste a ton of time and money, but I also miss my optimized idle and the check engine light is annoying. Would like to fix this myself if I can...

P.S. just thought of something... Maybe it's that little quiet beep that happens before optimized idle comes on? If so, does anybody know where that beep is actually located?

 

Actually, I just figured it out. Found a freightliner optimized idle aftermarket installation manual, and sure enough, it is the beep! A boxy looking little speaker thing on the driver's side of the firewall. Unplugged it, no change. Shorted the plug with a piece of wire (sloppy, I know), and code changed to fmi 925 spn 3 - pin 17 shorted. So the problem is with the speaker itself. It's a sealed unit, so I will have to get another one at dealership. Meanwhile I will try to somewhat destructively disassemble this one and maybe find the broken wire - what have I got to lose, lol. Pic of the ####### attached.

 

Yup, thanks. Sealed unit doesn't seem to want to come apart even under the most brutal caveman methods - it's one of those completely filled with solid gel kinda things. I guess I could get fancy and bypass it with a resistor, but I'm gonna see if I can just buy a replacement for a reasonable price first.

For now, my optimized idle is a 25lb exercise weight sitting on the gas pedal with fast idle on. Whatever works, i guess, lol.

Thanks for the help.

 

Yep, I saw that one too. The problem is, I'm pretty much homeless and hardly ever go to my parents house where I could get mail and eBay orders. So I'm going to see if Freightliner dealerships have them and if not then I guess I'll have to order it and find a load to Massachusetts so I can pick it up at my parents house.

Interestingly, it seems to be mostly used for back up alarms. I guess it's just a standard industrial beep