LKW CAN J1939

Hello all of you I am new here on the forum and first of all I want to say "whowww" what a brilliant forum.

Sorry that I write in the English langauge, my German is like Rudi Carel a fellow dutchman. I have no problem reading written German, so please do not hesitate to answer me in the German language.

My question is truck specific, I'm working on a project in wich I have to reduce the max torque, prefereble with a CAN command. Now I make use of a Truck Tuner who change the Torque limiter in the trucks ECU. Our ECU supports CAN 2.0 B as we use it to read CAN Engine messages. I know that it is possible to enter a second Engine Torque Map into the engines ECU I think that it has to do with PGN 65251.

My question: is there someone who know how to write these points into the ECU and how to switch between them?

Please help me, my project is stalling at the moment.

Cees

Hi Raysigher,

im Zusammenhang mit Programmierungen bzw. Entwicklung von SAE-J1939-Geräten, habe ich mich etwas mit dem Thema beschäftigen müssen - war sehr intessant.
Ich werde mal ein paar Kollegen von damals hierzu kontaktieren - mit welchem Erfolg, kann ich jedoch nicht sagen.
Warum sagst du 'I think that it has to do with PGN 65251' ?
Vielleicht eine dumme Frage, aber: Was ist ein PGN 65251?

Gruß moses

As I understand, this PGN only deliveres information but cannot be used to 'program' the ECU:

pgn65251 - Engine Configuration - EC -
Transmission Repetition Rate: On change of torque/speed points of more than 10% since last transmission. Alternatively , or every 5 s.
Data Length: 34 bytes
Data Page: 0
PDU Format: 254
PDU Specific: 227
Default Priority: 6
Parameter Group Number: 65251 ( 00FEE3 16 )
Bit Start Position /Bytes Length SPN Description SPN
1-2 2 bytes Engine Speed At Idle, Point 1 (Engine Configuration) 188
3 1 byte Percent Torque At Idle, Point 1 (Engine Configuration) 539
4-5 2 bytes Engine Speed At Point 2 (Engine Configuration) 528
6 1 byte Percent Torque At Point 2 (Engine Configuration) 540
7-8 2 bytes Engine Speed At Point 3 (Engine Configuration) 529
9 1 byte Percent Torque At Point 3 (Engine Configuration) 541
10-11 2 bytes Engine Speed At Point 4 (Engine Configuration) 530
12 1 byte Percent Torque At Point 4 (Engine Configuration) 542
13-14 2 bytes Engine Speed At Point 5 (Engine Configuration) 531
15 1 byte Percent Torque At Point 5 (Engine Configuration) 543
16-17 2 bytes Engine Speed At High Idle, Point 6 (Engine Configuration) 532
18-19 2 bytes Gain (Kp) Of The Endspeed Governor (Engine Configuration) 545
20-21 2 bytes Reference Engine Torque (Engine Configuration) 544
22-23 2 bytes Maximum Momentary Engine Override Speed, Point 7 (Engine Configuration) 533
24 1 byte Maximum Momentary Override Time Limit (Engine Configuration) 534
25 1 byte Requested Speed Control Range Lower Limit (Engine Configuration) 535
26 1 byte Requested Speed Control Range Upper Limit (Engine Configuration) 536
27 1 byte Requested Torque Control Range Lower Limit (Engine Configuration) 537
28 1 byte Requested Torque Control Range Upper Limit (Engine Configuration) 538
29-30 2 bytes Extended Range Requested Speed Control Range Upper Limit (Engine
configuration)
1712
31-32 2 bytes Engine Moment of Inertia 1794
33-34 2 bytes Default Engine Torque Limit 1846