DDEC II vs DDEC III

really DDEC-II may be fixed... but... now we have many DDEC-III and IV on JYs for low cost and really it is easier to upfrade now

 

DDEC-III and IV share sensors and wiring, DDEC-II wiring differs a bit.

Check it out
http://www.dmbruss.com/images/Schematics/DDEC/92_Engine_Wiring_Schematics.pdf

 

Ok, I gonna try to clear things.

Old DDEC-II was based on parallel EPROM (one programmable, other UV erasable), so in/out ports were "hard", cant be changed.

Later DDEC-III got FLASH and EPROM memory and it is more flexible, so truck makers got ability to do some vehicle specific things.

DDEC-IV is improved DDEC-III. This unit got CAN (J1922) and it can communicate with other units, like autoshift transmissions, ABS/ASR units (torq limit for traction control).

Later unused ports were used for EGR and Delta sensor. Aniway in early 2000-s DDEC-IV was old design (no J1939 support, lack of ports (PWM out for Vistronic fan clutch), low reliability (internal CMOS Li Battery leak, internal corrosion, cover problems), and DDEC-V was introduced.

Other step was European Temic ECM for MBE engines. This ECM was the first controlled by CAN only from VCI unit in cab (also calld FMR/FR on MB trucks and ADM on non MB trucks).

Later when detroit switched to MCM they use cab unit to control MCM and no so many wires of engine interface

 

Hello. I want to install a ddec2 in place of a ddec3 in a1995 Pete. I would like to run the ddwc2 ecm as it is a sweet running low mile engine. Does anyone know what mods or changes I will need to make to the vehicle wiring harness? Any and all info appreciated.