Need info on Class 2 data sent to instrument cluster

[Mr. Quick]

I'm working on a project in which I need to find out the exact protocol for the Class 2 messages sent to the instrument cluster. I'm very familiar with the UART information used in the 90's vehicles, but I don't know the Class 2 formats. I know that the message length varies, but I'm hoping someone with a good working knowledge of this can help.

The first part of my project is to be able to read these codes and output the information. My plan is to use a PIC Microcontroller and an LCD display for this purpose.

I greatly appreciate if someone can point me in the right direction.

[Mr. Quick]

So in researching, I've found the protocols for the J1850 VWP network, but I'm still having a hard time finding the message definitions. I am understanding how I will implement it into my project, but I still need to know, for example, how each message is sent regarding vehicle status (for example, what is the message ID for engine RPM, and how is it formatted. I know that in UART datastream definitions, most of the data would be sent as a value that would need to be multiplied by the instrument cluster to calculate the actual RPM value, or with a lookup table for items like temperature)

Anyone that can point me in the right direction?