Range Rovers Forum banner
1 - 3 of 3 Posts

· Registered
520 Posts
As you will glean from studying any wiring diagrams for the vehicles diagnostic connections or indeed the diagnostic lead, down loadable from the BBS forums,
The P38 has 3 separate diagnostic communications buses that all use different pins on the Diagnostic socket.
We call these, A, B and C for convenience,
C is a data pair used only for the Air suspension, This is in conjunction with a timer relay control wire, hence the clicking sound you are getting during he wake up attempts.
B is a data pair in the car which we short to one pin in the OBDII and is used only for the Airbag.

Leaving only A to be used for absolutely everything else. Naturally you should hear no clicking when attempting to access an ECU on channel A.

It is highly unlikely that you have a problem on the vehicle or indeed the Rovacom causing failure to communicate on all 3 buses.
Unless you have a faulty earth etc.

But it's worth while knowing and remembering exactly how the systems are divided up.

I like your assumption though, it makes a refreshing change :lol: :lol: :lol:
Of course now i said that it will probably turn out to be your Rovacom :|

Chas, as you say, Critical information to us and anyone trying to help :p
And yet we almost always have to ask that, but at least there was a wealth of other info to go on.



· Registered
520 Posts
No worries chap, you will know where to find me if you need any help.

And watch out for that ABS, after communicating with it, sometimes even if it cops out and causes an error, it is still awake and it ties up the whole of channel A so nothing on that channel can be spoken to, including the ABS itself, until the Ign is reset. :roll:

That actually catches a lot of people out, annoyingly it gives the impression that the equipment is intermittent or is over heating because it starts working ok, cus they chat with a few ECU's etc, then suddenly stops working which un plugging and resetting the Rovacom does not improve. Logic dictates the vehicle is OK cus it was working a minute ago. in frustration many unplug and switch of to go fume, let things cool down and have a cuppa, only to find when they come back, sure enough it's working again, but not for long.

Even when on just the ABS, i bet you click on read faults, which it flawlessly gets every time and makes you feel quite elated to be able to so easily access them, then you click on clear fault codes and after a few seconds it comes up with nothing but an annoying Red error screen for what seems like no reason. Which is of course a total let down just after it built you up just to make it even more infuriating when you are busy and you don't remember to reset the ign and just skip over the in screen reminder in auto pilot mode.

Or is that just me :lol: :lol: :lol:
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.