I'm troubleshooting a CAN bus issue in my 2001 SLK230. I'm currently showing 120 ohms on the high speed CAN pins at the ECU. I know that I should be reading close to 60 ohms as there are two 120 ohm termination resistors in the network. What I don't know is which modules have the termination resistors. Can someone inform me just which two modules on the network have those termination resistors in them???
hethcotehome
The resistors are in the Instrument Cluster and the ME-SFI engine control module. How are you measuring the ohms reading? If the pins are disconnected from the ECU, then a 120 ohm reading would be correct across the pins on the ECU (measuring the internal resistor) as well as the pins in the disconnected cable since you would then be reading the resistor in the Instrument Cluster. If you take a reading at the disconnected cable connector of the ESP module the reading should be 60 ohms. I am assuming that the negative battery terminal is disconnected.
Thank you sooo much! I found a broken wire behind the instrument cluster. Got it put back together and now I read 60 ohms at the ESP module with its plug disconnected and all the other plugs connected to their modules. However, this is a car that had major wiring harness damage which I want to think I've finally repaired. I'm now getting the following DTC codes:
TCM: 4 faults
1) 039 = CAN communication with the Engine System is Faulty.
2) 132 = (Resistance too Low) CAN communication with the Engine System is Sporadically Disturbed Or Engine Temperature is Sporadically Implausible.
3) 135 = (Resistance too Low) CAN communication with the Engine System is Sporadically Disturbed.
4) 136 = CAN communication with the Engine System is Faulty Or Engine Temperature is Sporadically Implausible.
Instrument Cluster: 1 fault
1) B1040 = CAN communication Fault To Engine Control Module
I ran a separate line from the pins on the TCM to the pins on ME-SFI engine control module hoping to bypass any faulty wiring in the harness but it didn't change these fault codes.
Any thoughts on how I should proceed???
TCM: 4 faults
1) 039 = CAN communication with the Engine System is Faulty.
2) 132 = (Resistance too Low) CAN communication with the Engine System is Sporadically Disturbed Or Engine Temperature is Sporadically Implausible.
3) 135 = (Resistance too Low) CAN communication with the Engine System is Sporadically Disturbed.
4) 136 = CAN communication with the Engine System is Faulty Or Engine Temperature is Sporadically Implausible.
Instrument Cluster: 1 fault
1) B1040 = CAN communication Fault To Engine Control Module
I ran a separate line from the pins on the TCM to the pins on ME-SFI engine control module hoping to bypass any faulty wiring in the harness but it didn't change these fault codes.
Any thoughts on how I should proceed???
If you have an AI account (ie. ChatGPT or Claude) you could ask AI how to proceed after sending the complete text of your post #3 to it for a recommendation. Likely next step would be to check the 12v and grounds for each module on the CAN bus.
Hopefully, some of the experts on the forum will chime in.
Hopefully, some of the experts on the forum will chime in.
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