Funky Can Network

Ryan Owner/Technician New Milford, New Jersey Posted   Latest   Edited  
Question
Driveability
2005 Acura RL 3.5L (J35A8) 5-spd (MJBA)—JH4KB16565C000195
U0073 - Control Module Communication Bus "A" Off
U0155 - Lost Communication With Instrument Panel Cluster (IPC) Control Module
U0122 - Lost Communication With Vehicle Dynamics Control Module
U0114 - Lost Communication With Four-Wheel Drive Clutch Control Module
B1168
B1169
B1170
B1173

good morning all I have a vehicle here that is really eating at me. customer states brake light and awd light came on. then the tach and speedo stopped working. confirmed his concerns. cleared these codes and they come right back on immediately . when you start the vehicle the tach works for about ten seconds before going back to zero. I can communicate with all modules currently. I scope the network by back probing at abs module and have found the can high to be at 3.5 volts flat line and low to be at 1.5 flat line. both at what seems to be resting voltage. there is absolutely no fluctuations in these voltages. I have tried unplugging every module with the exception of the pcm and nothing changes. with the voltage on the network where they are it does not seems as if there are any shorts to ground or power. for some reason there is just no data being communicated on the network. has any one seen anything like this or have any direction for me? any help would be greatly appreciated! thank you

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Vadim Owner/Technician
Dnipropetrovs'k, Ukraine
Vadim Default
 

Check the stop lamp bulbs. It is possible to install a lamp with one washing.

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Ryan Owner/Technician
New Milford, New Jersey
Ryan Default
 

Im sorry, your response is confusing. Could you elaborate on this?

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Brian Instructor
Parma, Ohio
Brian Default
   

Is the CAN bus flat lined as the tach is working? I believe that your scanner is communicating on the K line, so that is how you are communicating. Maybe try disconnecting the PCM and see if activity returns at the abs module?

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Ryan Owner/Technician
New Milford, New Jersey
Ryan Default
 

yes, the diagnostics are communicating through the k line. I did not check to see if can bus had activity during that few seconds but I will now. and I will also try the pcm. will replay back in a few minutes thanks

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Ryan Owner/Technician
New Milford, New Jersey
Ryan Default
 

Unplugging pcm did not wake up my can signal. There is no can signal when tach works for those few seconds.

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Brian Instructor
Parma, Ohio
Brian Default
   

So all modules on network unplugged I would check KOEO voltages on C H and C L , should be 0V if all modules off the network, then key off and add one module at a time. I had a logic lock situation (totally different vehicle) and doing it this way was able to find the bad one , and make sure that I had all modules off the network.

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Ryan Owner/Technician
New Milford, New Jersey
Ryan Default
 

I’ll try that today and get back to you. Thank you

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Gail Technician
Garner, North Carolina
Gail Default
 

Have you disconnected the radio and/or cluster?

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Ryan Owner/Technician
New Milford, New Jersey
Ryan Default
 

Yes I have

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Is this actually a 2005? According to the wiring diagrams an 05 Acura RL with a 3.5 doesnt have a high speed CAN network at pins 6 an 14??!! Someone correct me if I am wrong but I have scoured OE and color diagrams and there is no high speed CAN.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

I am sorry disregard my post. Wow the diagram is hard to understand lol. My fault.

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Stuart Mobile Technician
Blue Island, Illinois
Stuart Default
 

How many modules are on this vehicle because I only show 4 with the imformation I have available to me.

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Ryan Owner/Technician
New Milford, New Jersey
Ryan Default
 

6 modules

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Ryan Owner/Technician
New Milford, New Jersey
Ryan Resolution
 

Okay thanks you all for the help. The diagram I was looking at was Missing one module. That module was the navigation DVD player in the trunk deck. I unplugged this module and my network came to life. Checked power and grounds. Tested good. Vehicle has a bad nav DVD player that was making the network flat line. thank you all for the help

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