Troubleshooting of the DDEC III system and the DDEC IV system is identical. At the time of this
printing, the available features are the same in both systems. The DDEC IV system allows for an
increased processor speed and increased memory. DDEC III ECMs and DDEC IV ECMs are
Instructions for repair in this manual are generic. For example, "Repair Open" is used to advise
the technician that a particular wire has been determined to be broken. In some cases it may
not be best to try and locate the open. It may be that the best repair technique is to replace a
complete harness. The technician should make the determination of the proper repair, with the
best interest of the customer in mind.
Instructions to "Contact Detroit Diesel Technical Service" indicate that at the time of this
publication, all known troubleshooting checks have been included. Review any recent Service
Information Bulletins (SIB) or Service Information letters before calling.
It is also suggested that other DDC outlets be contacted. e.g. if you are a dealer or user, contact
your closest DDC Distributor.
Ensure you have the engine serial number when you call. The FAX number for Detroit Diesel
Technical Service is 313-592-7888.
Instructions in this manual may suggest replacing a non DDC component. It may be required
to contact the supplier of the component, e.g. truck manufacturer for a TPS concern, to obtain
approval to replace the component.
Instructions to check terminals and connectors should include checking for proper contact tension.
Using a mating terminal, a modest force should be required to remove a terminal from its mate.
Replace terminals with poor tension.
After completing any repair, always clear fault codes that may have been generated during the
To ensure you receive updates to this manual should the need arise, you must fill out the
Information Card in the front of this manual.
Be aware that troubleshooting in this manual is mostly concerned with DDEC related
codes. Codes associated with other components, e.g. construction and industrial, EDM
and AIM, can be found in the related publication. Refer to section 2.4.
All information subject to change without notice.
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION