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Need more info and U1040 is a bcm code, loss of communication .is this vehicle new to you? or can you give info of events that occurred prior to malfuction light illuminating . Vehicle engine size would help with suggestions on where to start your troubleshooting. but quickly Did you check all fuses? You Have multiple fuse Box locations. Not just underhood. That would be a good place to start your diagnosis.
U, B, C and P codes above P0800 are considered enhanced manufacturer specific codes. So without knowing the year, make, model and engine, nobody can answer your question.
The control module ID number list below provides a method for determining which module is not communicating. A module with a class 2 serial data circuit malfunction or which loses power during the current ignition cycle will have a Loss of Communication DTC set by other modules that depend on information from that failed module. The modules that can communicate will set a DTC indicating the module that cannot communicate. When no message is detected from a learned identification number for 5 seconds, a DTC U1??? where ??? is equal to the 3-digit identification number is set.
Control Module
ID Number
Powertrain Control Module (PCM)
016
Electronic Brake Control Module (EBCM)
040
Dash Integration Module (DIM)
064
HVAC Control Module or IPM
065
Rear Integration Module (RIM)
066
Inflatable Restraint Sensing and Diagnostic Module (SDM)
088
Instrument Panel Cluster (IPC)
096
Head Up Display (HUD)
098
Radio
128
Remote Playback Device - CD Changer
130
Digital Radio Receiver (DRR)
137
Vehicle Communication Interface Module (VCIM)
151
Driver Door Module (DDM)
160
Front Passenger Door Module (FPDM)
161
Left Rear Door Module (LRDM)
162
Right Rear Door Module (RRDM)
163
Memory seat Module (MSM)
166
Driver Door Switch Assembly (DDSA)
170
Remote Control Door Lock Receiver (RCDLR)
176
Theft Deterrent Control Module
192
The electronic brake control module is communicating , no need to bother the PCM . The code was set in pcm because it lost communication with EBCM , PCM not the problem .
Electronic Brake Control Module (EBCM)
Left Front lower corner of the engine compartment, under the air cleaner housing .
Check power's an ground's . Will a scan tool talk to it ?
DTC U1040 indicates that the ABS module is not capable of sending its state of health message. ( and this makes the ABS Light not flash ) check connections on the Module ...all fuses ...
Possable causes : Open ABS fuse Open battery circuit Open ground circuit Open serial data circuit Short to ground in power circuit ECU malfunction
I found a code chart at another web site.U1040 indicates no serial data communication with ABS module.I checked for wake up signal,it was there.I checked ground connection,it was good.I checked for B+ at module with DVOM and had battery voltage at both pins.I then load tested both B+ terminals and found the circuit was faulty.I went to the 30 amp ABS fuse and did a voltage drop test .I found the female connectors that the fuse plugged in to did not make good connection with the fuse.I bent the fuse pins outward and reinstalled.The ABS module came back on line.This bike has less than 2500 miles on it and this connection is already faulty.Is there a way to look up TSB'S for harley?.Bending the fuse pins is only a temperary fix.If there is no TSB for this problem I'm going to wire in a ATO fuse instead of the mini that Harley uses.The ABS motor draw on every start up appears to be excessive for that mini fuse connector.
P0621 - indicates a failure in the alternator lamp curcuit.
P0304 - indicates a miss fire was detected in the #4 cylinder
U1040 - indicates a loss of communication with the ABS system
U1000 - Indicates a class 2 communication loss
None of those codes are relating to a transmission failure (P0700-P0702)
I would have a visual look at the transmission and verify that all electrical wires are connected and tight. Then I would have the transmission serviced if it hasn't been within the last 35,000 miles.
Have the trouble codes cleared and address the ones that return.
After that you may be looking at an internal transmission adjustment and/or repair.
sounds like a new unit is required ,dealer only with you laying the golden egg ,could be sensor but i think more like the clima control computer.try running it in centigrade setting instead of obsolete farenheit ,it might confuse the computer and use a different circuit and work
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