Eaglefixer

I working on my neighbor 2003 Ford F150 5.4l Lariat and some of his dash warning lights stay on with the key removed. This also drains his battery and cause the truck not to start. I pulled his 5 amp fuse F2.2 that controls the Instrument cluster, Powertrain Control Module (PCM), Electric Automatic Temperature control Module (EATC) and the lights go out and truck starts fine but the blower goes on high to defrost and will not shut off. I pulled his radio and EATC out and reinstalled the 5 amp fuse and truck starts fine and everything is back to normal even when i cut the truck off. I took the cover off the EATC and inspect the inside but didn't see anything burnt or out of the ordinary. Any ideas. Can anybody post a copy of the Eatc Wiring Diagram please.

white89gt

Sounds like a wet GEM module to me.

Eaglefixer

No water leaks

BareBonesXL

Pretty lazy response to people offering help. Don't the signs point to a bad EATC? Electronic components don't have to show signs to be bad. They usually don't.

If you're lucky this file is still available.

https://www.f150forum.com/f6/2003-f-...8/#post7110484

Eaglefixer

.Sorry for the lazy response and thanks for the link to the wiring diagrams. I sure they will help out alot if and when the problem come back. I just ask the owner if he ever had any problems with water leaking in to cabin and he said no. I check under the hood to see if there was any debris in the rain trough on left side and it was clear. I did not take the GEM Module out to inspect it because i am handicapped and can't get down on my knees. Bad hips and knees.

Well i reinstalled the EATC and started the truck with the 5 amp fuse out and everything seems to working correctly. So then i just installed the 5 amp fuse and started the truck and again everything seems to be back to normal. All this was done with the radio out so i installed the radio and everything is checking out. I guess it could have been a loose connection or when i moved the wiring around they aren't chaffing anywhere now.

BareBonesXL

Overall, the diagnosis seems solid. Not uncommon to just lose a pin connection at an electronic component and get it back just by unplugging and reconnecting. I got a throttle position sensor error on a 95 Pathfinder and went through a whole tracking and testing procedure from PCM to the sensor and didn't find anything. The part and the wiring all checked out. Put it all back together and the code was gone and never came back. I think it was just a connection that hadn't been touched for 20 years finally losing its contact.

Good luck with it.