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Ficm problem any ideas.....

16K views 6 replies 4 participants last post by  PSDMikeB 
#1 ·
Hey everyone i've posted a couple times on here about my 6.0.Its a 03 f350 fx4.I have never had any issues out of my truck.I woke up couple weeks ago,started my truck and then let it warm up a few minutes.I put in reverse then str8 to drive.I got about 15-20 yards and the truck just cut off with no sign of hesitation.I had full starting power when it shut off so i tryed cranking and it wouldnt start.I pulled the batteries and replaced them with fresh 850cca batteries.Still no start,so then i pulled the ficm relay under the hood.Its was getting 12 volts on the leads that the relay plugs into.I bought a new relay and put it in and still no start.The reason I know it was having a fuel issue is because gas on a rag would fire the truck then cut off.I started checking other fuses and relays and they are ok under the dash.I have found the problem but im not sure what would cause this......The fuse under the hood # f1.1 is the ficm fuse.The fuse itself is good.BUT the fuse leads is not putting any power on the fuse...If I could get power back on that fuse then i believe she will start.What would cause that ficm fuse under the hood not to have power????I tested the ficm and it had no power on the screw on top 4 row lead(7pin)....Im running out of options, ive checked most of the wires under the hood and around the connectors plus replaced the ficm relay..just no power on the fuse under the hood for the ficm....Everything else has power and works...Help!!!!
 
#3 ·
Checked #22 plus all the other fuses under the drivers side dash and under the hood below the brake master cylinder.In the box under the hood there are 2 fuses.The 10amp ficm fuse is good,but if you test the prungs where you plug the fuse in,there is no power.I have power on the other fuse in front of it.I tested the relays and they all have 12.4 volts...Just no 0volts on the ficm fuse.Does the battery send power to the ficm or the pcm then to the 10amp fuse or does the battery relay the 10amp fuse then to the ficm and pcm????If i tested the correct wire on the ficm wiring harness then it had 12 volts.It was the only solid red wire on the harness.I tested the ficm 7 pin and it had no power on the screw test lead....so either that ficm is no good not sending power to that 10 amp fuse....the pcm is bad no allowing power to the ficm fuse then to the ficm..(but i dont think so since everything else is communicating.)Or there is a wire gone bad all off a sudden somewhere in the harness.If thats the case that would be crazy since i havent had no signs or no issue of a breakdown...any thoughts thanks for the info
 
#4 ·
I don't have a wiring diagram for a 2003, but the 2004 diagram shows the Fuse1.1 gets power from the FICM relay.

Do you have a service manual or wiring diagram?

Here is a screenshot.

MikeB
Text Technical drawing Diagram Line Plan
 
#5 ·
Thanks for the diagram!The ficm relay is a 4 pin relay.I replaced the relay and still no ficm fuse power.I tested the relay leads where it plugs in and it shows 12.4 volts.For some reason the ficm fuse 1.1 under the hood wont show no power on the leads where you plug in the fuse.All other relay and fuse leads test fine.
 
#6 ·
If you can leave the relay plugged in and get to the back side where the wires come out and test for power there. If the relay is working you should have power at the 876 wire (dg/lg). That is the wire that feeds the fuse. If you have power there then most likely it's a broken wire in between the relay and the fuse holder.
 
#7 ·
I'm not the best at reading wiring diagrams, but I think cweiss is on the right track. It appears that pins 1, 2, and 3 of the relay should have 12V when everything is turned off. When turned on, it appears as though there is a switch within the FICM that takes pin 2 to ground (so then pin 2 voltage should be very close to 0 V) which will cause the relay to activate and energize pin 5 of the relay to to 12 V which should feed 12 V to the fuse.

If pin 5 of the relay is at 12V, then broken wire going to the fuse.

If pin 2 of the relay stays at 12 V when turned on, then the FICM is not connecting pin 2 of the relay (Pin 27 of FICM connector) to ground to activate the relay. At that point I have no idea what the next step would be to figure why the FICM is not connecting to ground.

MikeB
 
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