Step 1 of 5
1
Find the FEF1 Lines in Your CAN Trace
What you're looking for:
The Two Speed Axle signal (SPN 69) lives in the CCVS message — the same FEF1 lines you use for brakes and vehicle speed. Find every line with FEF1 in your CAN King trace.
A CCVS line looks like this. The Two Speed Axle signal is in Byte 1:
CAN 1 6 0FEF1 21->* 8 F7 FF FF CF FF FF FF FF
FEF1 = CCVS message
Source Address (SA)
Byte 1 — Two Speed Axle lives here (bits 2&1)
💡 Note
Two Speed Axle is uncommon — not all trucks have it. If every FEF1 line shows FF in Byte 1, or all signal bits decode to 11 (Not Available), this truck does not broadcast a Two Speed Axle signal.
2
How Many FEF1 Lines Do You See?
Count every line with FEF1 in your trace. Each has a different Source Address (SA) — the two-digit hex number before the →*.
3
Enter Your Source Addresses (SA)
What is the SA?
It's the two-digit hex number before "→*" on each FEF1 line. Example:
We'll show the decimal value automatically — you'll need decimal when entering parameters in your display.
0FEF1 21->* — SA is 21.
We'll show the decimal value automatically — you'll need decimal when entering parameters in your display.
Enter hex values only (e.g. 00, 21, 31). Do not include "0x".
4
Enter Byte 1
Find this SA's FEF1 line and enter the value from Byte 1 (the very first data column after the DLC number).
Two Speed Axle (SPN 69)
5
Results
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Summary — Two Speed Axle SA