Step 1 of 6
1
Find the FEF1 Lines in Your CAN Trace
What you're looking for:
In Kvaser CAN King (Simple J1939 format), each line shows a message. You need to find every line that contains FEF1 — this is the CCVS message (Cruise Control / Vehicle Speed), which carries Park Brake, Service Brake, and Vehicle Speed signals.
A CCVS line in your trace looks like this:
CAN 1 6 0FEF1 21->* 8 F7 FF FF CF FF FF FF FF
FEF1 = CCVS message (what to search for)
Source Address (SA) — the module sending it
Bytes we care about (Park Brake, Service Brake)
Vehicle Speed bytes
💡 Tip
In CAN King, you can sort or filter by PGN. Look for FEF1 in the PGN column. There will often be multiple lines with FEF1 — each one is from a different module (ECU) on the truck. Each has its own Source Address (SA).
2
How Many FEF1 Lines Do You See?
Look through your trace and count every line that has FEF1 in it. Each line has a different Source Address (SA) — that two-digit hex number before the arrow (→*).
3
Enter Your Source Addresses (SA)
What is the SA?
The SA is the two-digit hex number before the "→*" on each FEF1 line. Example:
Enter each SA in hex. We'll show you the decimal value automatically — you'll need the decimal value when entering parameters in your display.
0FEF1 21->* — the SA is 21.
Enter each SA in hex. We'll show you the decimal value automatically — you'll need the decimal value when entering parameters in your display.
Enter hex values only (e.g. 00, 21, 31, E6). Do not include "0x".
4
Enter Byte Values
Enter the 4 hex byte values from this SA's FEF1 line. Bytes 5–8 are not needed and are grayed out.
5
Results
6
✅ Summary — What To Use In Your Parameters