Spy Networks Tab: J1850 VPW Mode

The Tools -> Options, Spy Networks tab lets you select how the J1850 VPW headers are handled as shown in Figure 1.

Option 1: Select the default GM Class 2 version with a three byte header (PT, Trgt, Src).

Option 2: Select Chrysler version with a one byte header (ID).

The J1850 VPW Mode setting affects many areas of Vehicle Spy, including Messages view and the Messages Editor. When decoding signals, for example, a reference to the first data byte (B1) of a J1850 message actually means a reference to byte 2 in Chrysler mode or to byte 4 in Class 2 mode.

Figure 1: Selecting the J1850 VPW Mode.