U0100 & U0101
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Mountain Pass
Joined: Sep 2010
Posts: 237
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From: Wyoming
U0100 & U0101
My wife's 05 excursion with the 6.0 started throwing a code for U0100 and sometimes it has U0101 with it as well. It had a no start condition and I found a bad battery cable. Now it starts but I still have the U0100 and every once in a while it runs kind of bad like it has a misfire or something. No engine light for that you can just feel it. And it's not all the time. Any suggestions? Could the PCM be trying to go out? Thank you
Fleet Mechanic
Joined: Jan 2023
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Likes: 449
You may have a problem with the communication wiring. But a bad module like the PCM can bring down the network. Troubleshooting CAN bus networks can be tricky. A good start is to trace the wiring and look for physical damage to the wire and connectors.
A wiring diagram will help.
https://charm.li/Ford/2005/Expeditio...0Diagram/25-1/
A wiring diagram will help.
https://charm.li/Ford/2005/Expeditio...0Diagram/25-1/
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Mountain Pass
Joined: Sep 2010
Posts: 237
Likes: 1
From: Wyoming
Thank you for the wiring diagram. So far I have found one ground strap that has a little cut in it and one that may be a little dirty. Going to go get a new ground strap to replace that one and clean up the rest. Will report back afterwards. Thank you.
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Mountain Pass
Joined: Sep 2010
Posts: 237
Likes: 1
From: Wyoming
Well I got all the cables cleaned up and put back together and the broken one replaced. Seems to run fine now but that code will not go away. Last time we started it the radio told us it was ejecting the DVD. We didn't touch anything in the DVD player. Starting to think the computer may be going bad?
Fleet Mechanic
Joined: Jan 2023
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Are you using a scan tool that can view data PIDs like misfire count? The communication errors and P-codes may not be related. Low voltage can cause all sorts of issues and you may have fixed that. Now you should concentrate on the poor running condition.
Torque Pro has a phone app (not the free version) that will display a lot of PIDs. You need an adapter to connect to your vehicle. Forscan is free and you use the same adapter along with a PC (no Apple products).
I would look at misfire data. The reasons for misfire can be numerous but a common one is a bad COP (coil on plug). Swapping COPs and viewing the corresponding misfire data is helpful. Replacing all COPs (and spark plugs) with Motorcraft or Denso units is easier but more expensive.
Torque Pro has a phone app (not the free version) that will display a lot of PIDs. You need an adapter to connect to your vehicle. Forscan is free and you use the same adapter along with a PC (no Apple products).
I would look at misfire data. The reasons for misfire can be numerous but a common one is a bad COP (coil on plug). Swapping COPs and viewing the corresponding misfire data is helpful. Replacing all COPs (and spark plugs) with Motorcraft or Denso units is easier but more expensive.
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Mountain Pass
Joined: Sep 2010
Posts: 237
Likes: 1
From: Wyoming
This is a 6.0 powerstroke. I just got my auto enguinity up and running. The FICM voltage is between 47.5-48 volts and the voltage into the FICM is 13-13.5V. ICP is .88V and 581.25 psi IPR is 24.61%. This is all at idle. While doing this after running for few minutes i notice the RPM's jump slightly and it acts like is misses but gives me no codes. I ran all the tests that were listed on auto enguinuity and the only bad thing it comes back with is P1703 brake switch code.
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Mountain Pass
Joined: Sep 2010
Posts: 237
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From: Wyoming
Okay so I had my wife drive while I watched the FICM V the FICM main power the ICP V and ICP pressure. All four will basically take turns dropping to 0. They don't do it at the same time but they all do it. Once it will be the FICM power then a minute later it's the Main power then a bit later it'll be the ICP volts. I can't get it to do anything weird when I wiggle wires while it runs and can't find any wires that looks bad. Any suggestions?
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Fleet Mechanic
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You need to determine if the signals are actually dropping or if the PCM and/or network are faulty. ICP goes directly to PCM. I would monitor with a voltmeter and look for a dropout on your scan tool.
https://charm.li/Ford/2005/Excursion...0Diagram/26-8/
FICM appears to communicate to the PCM over the network.
https://charm.li/Ford/2005/Excursion...0Diagram/26-3/
If you can graph the signals it may show a pattern. Maybe add other PIDs not associated with the PCM to see if the problem is network-wide.
https://charm.li/Ford/2005/Excursion...0Diagram/26-8/
FICM appears to communicate to the PCM over the network.
https://charm.li/Ford/2005/Excursion...0Diagram/26-3/
If you can graph the signals it may show a pattern. Maybe add other PIDs not associated with the PCM to see if the problem is network-wide.
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Mountain Pass
Joined: Sep 2010
Posts: 237
Likes: 1
From: Wyoming
I went back and looked at the recorded data and i got no data where it cut out for every sensor i had at random times. Vehicle speed, IPR %, Vehicle fuel level and Accelerator position sensor. Anything I had pulled up did it I just wasn't paying much attention to them at the time.
Fleet Mechanic
Joined: Jan 2023
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I think you are back to the original problem of communication faults. Something is causing the network to be interrupted it appears. I don't know exactly how to troubleshoot this. Use the Charm website link to go through the wiring diagrams and map out the CAN network. These older vehicles don't have a lot of modules in the network so hopefully it is not too complicated. Since everything works most of the time it may not be useful to do a resistance check on the network (the network has termination resistors at each end). I would trace the wires and look for a damaged wire. I know that's not very sophisticated, so maybe someone else can provide better advice.
Go to YouTube and watch a video on troubleshooting automotive CAN networks to see how they work.
Go to YouTube and watch a video on troubleshooting automotive CAN networks to see how they work.
Fleet Mechanic
Joined: Jan 2023
Posts: 1,332
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It looks like the HS CAN only goes between the FICM, PCM and data link connector.
https://charm.li/Ford/2005/Excursion...%20Network%29/
It should be reasonably easy to check the connections between those three components.
https://charm.li/Ford/2005/Excursion...0LH%20Side%29/
Look for rubbed wire insulation and corrosion in the connectors.
https://charm.li/Ford/2005/Excursion...%20Network%29/
It should be reasonably easy to check the connections between those three components.
https://charm.li/Ford/2005/Excursion...0LH%20Side%29/
Look for rubbed wire insulation and corrosion in the connectors.
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Mountain Pass
Joined: Sep 2010
Posts: 237
Likes: 1
From: Wyoming
Well I went through all of that plus some. Only thing that looked questionable was the charge wire from the alternator. I replaced an end on it just in case. All the wiring and connectors look good. I unplugged them and they’re dry and corrosion free including the PCM connectors and FICM. As of right now it seems to be running good and the U0100 went away. I’m not to entirely sure why but it did. Hoping it stays that way. Thanks for the help.
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