SPN 231 - FMI 12 (Fault Codes: J1939 Data Link Failure/ Code 55)
Engine Check - Code 55 (12V2000 Detroit Engine)
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| Figure 1.1 - Code 55 (J1939 Data Link Failure) |
SPN 231 - FMI 12/ J1939 Data Link Failure (Master/ Receiver)
SPN 248 - FMI 8/ Proprietary Data Link Fail (Master)
SPN 248 - FMI 9/ Proprietary Data Link Fail (Receiver)
1). Description of Flash Code 55
Flash Code 55 indicates the ECM, see Figure 1.2 below, has detected a fault in the J1939 Data Link.
Multi-ECM Engines may have two areas able to log a Flash Code 55, the SID identifies which
area of the ECM is reporting the fault.
Flash Code 55 typically indicates:
→Incorrect programming
→Wiring fault
→Failed ECM
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| Figure 1.2 - DDEC IV ECM |
2). SAE J1587 Equivalent Code for Flash Code 55
The SAE J1587 equivalent code for Flash Code 55 is S 231/12, J1939 data link fault, 248/8 Proprietary Data Link Fault/ Master, 248/9 Proprietary Data Link Fault/ Receiver (1 and/or 2).
3). Troubleshooting Flash Code 55
(B). Test Step 2 - Check for Nodes
(A). Test Step 1 - Determine the Fault
Perform the following steps to determine the fault.
a). Turn ignition ON.
b). Plug in the DDDL, read Active Codes. Read More: How to Connecting the DETROIT Engines using Detroit Diesel Diagnostic Link (DDDL).
→If code 231/12 displays, refer to Test Step 2. If code 248/8 or 9 displays, refer to Test Step 4.
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| Figure 1.3 - Fault Codes (Flash Code 55) |
Perform the following steps to check for nodes:
a). Inspect the six–pin communication harness connection at the ECM to determine if any
wiring is present. If wiring is present, refer to Test Step 3. If no wiring exists, perform one or all of the following: →Verify need, or replace the termination resistor (plug).
→Change Transmission definition to another selection and back to the correct one.
→Replace ECM.
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| Figure 1.4 - Termination Resistor (120 ohms) |
Perform the following steps to check the ECM:
a). Unplug the communication connector.
b). Turn the ignition ON.
c). Read Active Codes with the DDDL.
→If no Active Codes display, the fault is within the OEM wiring or other devices using
the J1939 data link. If code S231/12 displays, replace the ECM.
(D). Test Step 4 - Check for Short
Perform the following steps to check for a short:
a). Turn the ignition OFF.
b). Unplug both (or all) Engine sensor harness 30–pin connectors.
c). Measure resistance between cavity L3 (925) and M3 (926) of each connector removed.
→Any reading less than 5 ohms, indicates the wires 925 and 926 are shorted together.
Repair the short. If all readings are greater than 5 ohms, refer to Test Step 5.
(E). Test Step 5 - Check for Open
a). Insert a jumper harness between L3 and M3 of the Master ECM connector.
b). Measure the resistance between L3 and M3 of each other connector removed.
→If any reading is greater than 5 ohms, it indicates one of the wires (925 or 926) is open.
Repair the open. If all readings are less than 5 ohms, replace the ECM.
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| Figure 1.5 - ECMs (Master and Receiver) |
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