56.3 TROUBLESHOOTING FLASH CODE 56
The following procedure will troubleshoot Flash Code 56.
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. Visually check the DDR for codes.
[a] If codes other than 250/12 are logged, service them first.
[b] If code 250/12 is logged, and no other codes are logged, Refer to section 56.3.2.
[c] If no data is logged, refer to section 9.1.
Perform the following steps to clear codes.
1. Clear codes.
2. Start and run the engine.
3. Observe CEL/code.
[a] If CEL is on with code 250/12 logged, refer to section 56.3.3.
[b] If no CEL code is logged, refer to section 56.3.5.
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.
[a] If any OEM devices are installed, refer to section 56.3.4. Refer to step 1
[b] If no OEM devices are installed, refer to section 56.3.4. Refer to step 2[a]
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.
All information subject to change without notice.
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION