Well, the truck sat for around 5 or 6 days.
Went to start it, it was dead as could be.

Charged up one battery and restarted fine.
I went down to a friends shop and we found a 1 amp draw in the stereo, under hood lamp circuit.

How would this issue be fixed? What in the hell is the FCM and where is it?

Thanks for any help with this issue!!

 

Im dealing with something similar.

Check the thread:

https://www.dieseltruckresource.com/...ad.php?t=77730

Driving me to drink.

 

You need to isolate the under hood light and/or the stereo to determine the culprit. While you're doing that, disconnect both of them and see if there still is a current flow. If there is, go see what else is on that circuit.

One amp seems like a lot. I wouldn't think a trickle current to keep the radio memory alive would take nearly that much, same goes for the lamp.

Dunno about the FCM; where'd you see that, and what's the acronym stand for?

BTW, with the batteries in parallel, charging up "one" battery means you're charging them both (if they're installed in the truck).

 

Usually when I am diagnosing and electrical draw, the most I like to see is 0.1A draw. 1A is definitly excessive. First off do you have anything aftermarket? Guages? Aftermarket Stereo, radar detector, Programmers or boxes? Anything? If you do I find that 95% of the time it is usually an aftermarket/accessory item that was installed after delivery. Start with those items first. I assume you already pulled the fuse for the stereo/underhood light? I also assume the draw went to 0A approx? I also assume you did not have the hood open (hood light activated), the key in the ignition, doors open or anything else. If you didn't then I would get a good wiring diagram and start by tracing what connectors are in the circuit. Then start by disconnecting connectors until there is appropriate draw. for instance...unplug the radio, is there still a draw? Then it's not the radio. Unplug the hood light, is there still a draw? Then it is not in the light assy? Start unplugging any other connectors in the circuit until you find the culprit. Once you find which compnent or cicuit is causing the problem you will still have to find out what is drawing? I have seen stereo's that have an abnormal internal draw causing problems (not saying this is what it is for sure) but I have also seen wire insulation that is weak and causing a very small short but there is still enough resitance to not blow a fuse. Usually it is a component that is faulty however, like a switch or stereo or control unit.

Hope this helps.

 

How are you checking for this draw? If you are doing it old school you may not be providing enough amperage for the modules to wake up and communicate. What you probably want to do is use one battery leaving the other unhooked. + is left hooked up, - is unhooked. Run a decent size jumper wire from the bat - to the - cable end, and then hook your meter up in parallel with that jumper wire. When first connected it may take up to 15 minutes for some modules to time out. Your meter will show 1/2 the amperage draw. FCM is "forward control module" and is attached to the PDC.

 

i had that problem once i left my aftermarket fog light on but stupid me took switch power from wrong spot hard to discribe but dc told me to feed my switches with the ciggerett lighter stupid me had a brain fart and went to the power outlet instead but once i changed it never again