2003 Ford F350 6.0L Powerstroke Won't Start with Multiple Codes - Is FICM Faulty?

I own a 2003 Ford F350 Diesel with the 6.0L Powerstroke engine. One day it started and ran normally, but the next day it would only crank and not start. The fuel pump activates when the key is turned on and shuts off after a few seconds as expected. I replaced both fuel filters to rule out clogged filter issues. The following diagnostic codes appeared: - P0232: Fuel Pump Secondary Circuit High - P0261: Cylinder 1 Injector Circuit Low - P0264, P0267, P0270, P0-than 273, P0276, P0279, P0282 — all indicating similar issues across cylinders 2 through 8. - P0336: CKP Sensor A Circuit Range/Performance - P0500: Vehicle Speed Sensor A Since all eight injectors show identical fault codes, I tested the FICM. During the KO (Key-On) buzz test, the voltage read approximately 17.6 volts — significantly below the expected 45 volts. In the crank test, the voltage rose to about 48 volts but then dropped back down to around 18 volts. The question is: Does this strongly indicate a failing FICM, or could there be another underlying cause I should investigate before replacing the module? I'd appreciate insights from experienced users before investing in a new FICM. Thanks for your help.