I have a 2008 f-450 6.4. The battery light briefly came on one morning. After work it came on and I could smell hot wiring from under hood. I checked dtc's and it showed overcharging. I replaced both alt's. The batt. light stayed on constant but everything seemed to be working. I had alt's checked and were charging ok. Had batt's checked. All ok. Went to work one morning, everything fine except for batt. light. Tried to leave at noon and the batt's were dead. I checked for amp draw. With everything off it started at 5 amps. And slowly climbed to over 11. I don't know how high because it blew the 11a fuse in my meter. I have removed and visually checked the wiring harnesses for both alt's. Also checked continuity. All ok. I checked that the PCM was talking to alt's. Again ok. I have pulled all fuses and relays both under hood and dash one at a time to try to locate circuit. No change. I pulled the wire leading to under hood power center from divers side batt. Draw went to 100ma. I removed power center and inspected all wiring. All ok. I'm not sure where to go from here. Can anyone help me?

 

Wherever that hot wiring smell came from would be the first place to look. I have no idea where to look though. Perhaps the battery cable going to the starter? Maybe the Glow Plug Relay is staying on? And I don't know where it is located.

 

unhook one battery completely. unhook the ground lead from 2nd battery. Connect one end of a test light to the negative post of the 2nd battery, and the other end of test light to the negative lead of 2nd battery. with key off, if you have a draw (which you do, you said so yourself) the test light will light. Proceed to unhook various electrical components and systems. Follow the electrical path of the component that, when unhooked, give no light condition on the test light.

I think you were already doing that, but it is a lot easier with a bulb compared to using a multimeter...

 

Thanks Gino. Essentially that is what I am doing. The reason I use a meter is in using a test light you can possibly feed either + or - the wrong way to a circuit causing damage or destroying electronics, PCU, etc. The filament in the light bulb acts as a fuse but it wouldn't burn through before the damage has already been done.
I have eliminated everything under the hood and am now working my way across the dash one component at a time.
I'll keep everybody posted.

 

Hi everybody. I wanted to update on the issue with my truck. The problem turned out to be the Glow Plug Control Module (GPCM). I found this with the help from a buddy who works as a electrical tech at Komatsu. He informed me a draw that high was in the area of what glow plugs draw on their tractors so after tracing it down it turns out there are two 50a fuses for the GPCM. When I pulled one there was very little change but with both out the draw went down to 35ma. After this I checked the resistance on each glow plug individually to see if there was one that might be off from the others. They all checked the same. I did this by checking the wires that feed the glow plugs in the molex plugs to ground. This told me all were ok. I then pulled the GPCM and checked the resistance on the correlating pins to the pins that supplied power and all were the same except one, I think all but the one read .302 ohms. The odd one read 575 ohms. This one fed the cylinder number 4 glow plug which is the one that showed a problem when I checked for DTC's. I replaced the GPCM and everything is working great.
I hope this will help anyone that might encounter a problem such as this.

 

Thanks for reporting back, glad you got her all fixed up!

 

Hello. It's me again. It looks like the GPCM isn't the entire problem. The battery MIL has come back on. I ran codes and am getting P163A (Generator B Control Circuit). This is the same code I got when this all started therefore I am afraid to drive the truck for fear it might burn out the GPCM again. I'm wondering if anybody else has experienced this particular code issue and what it would take to remedy it.

 

Did you clear the codes since you fixed the issue?

Did you check to see if the voltage draw is gone?

With the #4 GP having that much resistance, did you fix that problem?