DDEC III/IV Single ECM Troubleshooting – Section 56.3 Troubleshooting Flash Code 56

Section 56.3
Troubleshooting Flash Code 56

The following procedure will troubleshoot Flash Code 56.‪

Section 56.3.1
Multiple Code Check

Perform the following steps to check for multiple codes.‪

1. Turn vehicle ignition switch ON.
2. Plug in the diagnostic data reader (DDR).
3. Read active codes.
   1. If codes other than 250/12 are logged, service them first.
   2. If code 250/12 is logged, and no other codes are logged, Refer to "56.3.2 Clear Codes" .
   3. If no data is logged, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .

Section 56.3.2
Clear Codes

Perform the following steps to clear codes.‪

1. Clear codes.
2. Start and run the engine.
3. Observe CEL/code.
   1. If CEL is on with code 250/12 logged, refer to "56.3.3 Check for Devices of Original Equipment Manufacturer" .
   2. If no CEL code is logged, refer to "56.3.5 Verify Repairs" .

Section 56.3.3
Check for Devices of Original Equipment Manufacturer

Perform the following steps to check for OEM devices.‪

1. Turn vehicle ignition OFF.
2. Determine if any OEM equipment utilizes the J1587 data link. (ABS, ProDriver®, satellite systems, etc.
   1. If any OEM devices are installed, refer to "56.3.4 Disconnect Nodes (Data Link Devices)" . Refer to step 1 .
   2. If no OEM devices are installed, refer to "56.3.4 Disconnect Nodes (Data Link Devices)" . Refer to step 2a .

Section 56.3.4
Disconnect Nodes (Data Link Devices)

Perform the following steps to disconnect the nodes.‪

1. Disconnect OEM installed devices, one at a time e.g. ABS, satellite systems, etc. Verify ABS switch is not in "Test" mode.
   1. If the disconnect does not solve the problem, continue the procedure.
   2. If the disconnect solved the problem, go to .
2. Connect vehicle interface module, J 41005.
3. Start and run the engine.
4. Observe CEL codes.
   1. If CEL or codes displayed, and the CEL is on with code 250/12 logged, replace the ECM with a test ECM. Refer to "56.3.5 Verify Repairs" .
   2. If no CEL or codes are displayed, contact OEM for instructions on how to proceed. Refer to "56.3.5 Verify Repairs" .

Section 56.3.5
Verify Repairs

Perform the following steps to verify repairs.‪

1. Turn vehicle ignition OFF.
2. Reconnect all connectors.
3. Start and run the engine.
   1. If the CEL or codes are displayed, and if code 250/12 is logged, all system diagnostics are complete. Review this section to find the error.
   2. If the CEL or codes are not displayed, troubleshooting is complete.