I have a 2007 F150 5.4 w/47,000 -- trouble free, until now

I typically drive my ranger when I commute, so my F150 had been sitting for a couple of weeks. The battery was dead--probably left my Sirius on again, so I used a portable jumper to start it. It fired right up and proceeded to use the truck throughout the early part of the day without any problems. That afternoon, while driving home, my interior electrical started going a little crazy.

My interior accessories (radio, windows, instrument panel, dome light, chime) are randomly turning on and off and the gauges are all over the place. This occurs with the engine running or engine off with the key in the accessory position. Additionally, if I remove the key while the problem is occurring, the gauges will continue to bottom out and twitch for a minute or so, accompanied by a buzzing sound. Occasionally, the everything will stay on for a while, but tire warning, airbag lights will flash then stay on -- it's a mess

After some searching, I found that the PCM relay is clicking randomly, which coincides with the on/off of my accessories. I pulled the accessory delay relay, which leaves all accessories off, and the PCM relay continues to act up and gets quite warm. I also swapped relays with no success. I've also disconnected the battery overnight and it appeared to help but the problem came back after a couple of hours.

The truck is drivable, just a little annoying with the occasional flashing dome light, chime, no radio, no gauges and inoperable windows. Other than that, not a big deal really :-/

Any ideas? It'll be off to the dealership Tues, I guess.

 

I had similar problems few years ago in my Dodge Caravan and I replaced the battery. Problems went away immediately. My suggestion is to load test the battery first.

Hope this will help.