I'm trying to understand why the cheaper OBD2 readers don't 'see' all
modules in the Jaguar's electronic network.

For instance, according to the JTIS diagrams, the DSC modules in the XK8 are on the same CAN bus as the ECM. My Gendan reader (which uses the ELM327 chip) can see the latter but not the former.

Is there a restriction in the software or hardware? Is that why we pay a premium for the AutoEnginuity's Jag. option?

Andrew

 

The generic readers will not pick up C or B codes, I think it's that simple.

 

There's not one cause. Some probably won't look for / see B/C/U codes (I'm guessing, but it's plausible).

But take a generic elm327. It can and will see those and can also see other modules - if the software talking to it (call it "the app") does the right things. The elm327 is a microprocessor (a simple one) with RAM etc. The problem is knowing how to go about getting it to chat to the other modules.

If "the app" is custom written to know jag modules or cunningly written to figure them out, then great off you go.

Or, if the app can be customised, as say Torque Pro looks like it can be, then you've a chance.

Probably easier to just get a Mongoose JLR if that would support the car you have in mind.

 

Or U codes

That's pretty much it, for example, if you have an airbag problem, it's a B code, if you have an ABS problem, it's a C code, if you have a canbus problem, it's a U code, and a cheap little pocket scanner cannot see these at all...