2003 Ford F150 4x4 4.6L Engine P1633 Fault: No Power to Pin 55 at PCM - Fuse 32 Missing?

Model: 03 F150 4x4 4.6L Fault Code: P1633 Posted: 2015-11-24 23:37

I'm experiencing a P1633 diagnostic trouble code on my 2003 Ford F15-0 4x4 with a 4.6L engine. The fault indicates that the KAPWR (Key Access Power) signal is not being received by the Powertrain Control Module (PCM). According to the service manual, there should be power supplied to pin 55 from the battery via a fuse or fusible link. However, I'm observing no voltage at pin 55. I've tested for continuity between pin 55 and the instrument cluster as well as the CJB (Central Junction Block), but there is no open circuit detected. The wiring diagram shows that fuse 32 should supply power to this circuit, yet I cannot locate or find this fuse in the fuse box. My question is: Where does the required power originate from? Is it supplied directly by the PCM itself, or is it routed through a generic module (such as the body control module) before reaching the PCM? Any insights or troubleshooting steps for this P1633 issue on the 2003 F-150 would be greatly appreciated.