Truck starts ONLY if PCM relay is unplugged & plugged back in, or disconnect & reconnect battery. If truck sits the battery (new one) drains as if something is on.

Background. Few days after new battery install truck would crank but not start. Thought fuel pump because we couldn’t hear it when key was on, but wanted to rule out fuses and relays. Visually checked fuel pump fuse and looked good. Next I swapped PCM relay with fog light relay and it started, but as soon as I turned it off same problem comes back. If I simply unplug the PCM relay and plug it right back in the truck will start. Once started it runs great. We used an OBD reader and only got a P1000 code, which is a result of unplugging the PCM relay. Tried second key, but same problem. Thoroughly cleaned terminal lugs, same problem. I’m thinking it’s the PCM itself but that’s an expensive guess. Suggestions?

no, sir but will do so - THANKS! Have to travel for work but will respond after I get back and take a look

I dropped the spare and visually checked the FPDM outer body and unplugged it to check electrical connection. The body really doesn’t look bad considering it’s an 06 w/195K mi. No rust. The pins are clean and it was easy to remove. I really have no other means to check it that I’m aware of. Would you proceed with changing it out anyway, or move to another step?

I removed FPDM from frame and no rust or corrosion, just the white oxidation type which wasn’t that bad. Brushed it clean and reinstalled. Same issue with starting though I noticed that with radio off, the CD stack kept clicking as if it was changing CDs. Made me think this was the source of draining the battery but it finally stopped after about 10 min.

Since it will start with a disconnect/reconnect of power source to the PCM I think it rules out everything but the PCM. Think it’s time to hand it over to the folks with all the tools, though I still prefer to whip this myself.