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Thread: 1125R Diagnostic Codes

  1. #1
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    1125R Diagnostic Codes

    Found out that the IC (instrument cluster) can show why the check engine light is on and so on.

    Well my bike has 3 issues

    U0001 - Comm Error
    B1005 - Low Fuel Sys Error
    P0193 - Fuel Pressure Sys Error

    Anyone got any guess before I follow what the electronic diag manual says to do?

    Possibilities:

    - Bike sat for 2 years in garage of rural area. Mouse chewed on a wire.
    - Bike sat with low fuel and the fuel pump is wonky because it hasn't had fuel in a long while
    - Bike sat and now that it has fuel the bikes losing its mind.

    It's too cold to screw with it now even in a garage(non insulated). I think I'll let it sit until its decent enough outside that my hand won't freeze without gloves on.

  2. #2
    Senior Member d_adams's Avatar
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    Paraphrasing from the Electronic Diagnostic Manual, ECM sets condition U0001 if it loses communication to the insturment cluster. If the fault happened when the ignition was off, "Theft Error" is set. If the fault happened when the ignition was on and communication between ECM and IC was occurring, "Comm Error" is set. If you have "Comm Error" then shut the bike off and restart, it becomes "Theft Error". The fault tree is very explicit. Dispositions range from replacing the ECM to replacing the IC, as well as a number of short / open circuit possibilities.

    B1005 is the resistor in the fuel tank, it's going out of spec and turning on the low fuel light.

    P0193 is related to the same, fuel pump pressure not maintaining what's required. Most likely, a new fuel pump would fix the last 2 problems.

  3. #3
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    Quote Originally Posted by d_adams View Post
    Paraphrasing from the Electronic Diagnostic Manual, ECM sets condition U0001 if it loses communication to the insturment cluster. If the fault happened when the ignition was off, "Theft Error" is set. If the fault happened when the ignition was on and communication between ECM and IC was occurring, "Comm Error" is set. If you have "Comm Error" then shut the bike off and restart, it becomes "Theft Error". The fault tree is very explicit. Dispositions range from replacing the ECM to replacing the IC, as well as a number of short / open circuit possibilities.

    B1005 is the resistor in the fuel tank, it's going out of spec and turning on the low fuel light.

    P0193 is related to the same, fuel pump pressure not maintaining what's required. Most likely, a new fuel pump would fix the last 2 problems.
    Now I've noticed the fuel pump is on the back of the frame. Is there a way to remove it without completely removing almost everything out back?
    If I replaced the pump, I can find just the pump, not the assembly. Is the assembly where this resistor is hiding?

    For the U0001, I am going to go through the diagnostic flowchart and see what happens. Hopefully it's the resistor in the CAN BUS plug.

  4. #4
    Senior Member Cooter's Avatar
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    Both the comm error and low fuel pressure error could be caused by sitting, dead battery, no gas...

    The fuel pump is easy to get to if you hang the rear of the bike from a rafter or A-frame ladder, remove the lower shock bolt and let the swing arm hang.
    You can get to the drain plug in the flange to drain the tank and then the removal of the flange/fuel pump assy is pretty easy from there.

    I'd clear the codes and wait to see what it does with fresh gas and a fresh battery before I started down that wormhole.

  5. #5
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    Quote Originally Posted by Cooter View Post
    Both the comm error and low fuel pressure error could be caused by sitting, dead battery, no gas...

    The fuel pump is easy to get to if you hang the rear of the bike from a rafter or A-frame ladder, remove the lower shock bolt and let the swing arm hang.

    I'd clear the codes and wait to see what it does with fresh gas and a fresh battery before I started down that wormhole.
    Battery is getting replaced, but does test and hold a charge fine. Will show up tomorrow(providing USPS estimate is accurate)

    I see. I saw a pic of what your talking about. Im glad I can do it without any real disassembly.

    How can I do this thru the cluster? Just get back into diag mode and hit mode on each code? Just used toggle to view them.

    Also, cant I just use diag mode to give me a quick and dirty fuel pressure test, by viewing live data?

    Thanks for the help. Im a new Buell guy, but familiar with motorcycle maintenance.

  6. #6
    Senior Member Mesozoic's Avatar
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    I'd be concerned about rectifying the Comm Error first and foremost as the IC is communicating with the ECM via CAN bus. Since that is a very simple 3 wire interface (CAN high, low, and ground) and known to be very robust, any legitimate issue with the CAN bus would lead me to believe that all other errors are secondary. I suppose you could use the diagnostic RS-232 interface on the bike to verify that the errors you're seeing are the same as on the CAN bus. I bet there's a short in the harness somewhere from a packrat chewing or something like that, although I've seen bad chafing do it too.

    Edit: I'm now unsure of whether the IC is fed CAN data or not. It might be RS-232. In any case, that's just Tx, Rx, and Ground.
    Last edited by Mesozoic; 02-08-2018 at 09:55 PM.

  7. #7
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    Glad I found this thread, the mechanic found these codes along with a few others (others were to do with the fan). So fingers crossed It is a simple fix.

  8. #8
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    Quote Originally Posted by Cooter View Post
    Both the comm error and low fuel pressure error could be caused by sitting, dead battery, no gas...

    The fuel pump is easy to get to if you hang the rear of the bike from a rafter or A-frame ladder, remove the lower shock bolt and let the swing arm hang.
    You can get to the drain plug in the flange to drain the tank and then the removal of the flange/fuel pump assy is pretty easy from there.

    I'd clear the codes and wait to see what it does with fresh gas and a fresh battery before I started down that wormhole.
    So is that the main reasons for the fault codes?



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