My 2008 X350 has collected several faults, including an EGR wiring issue that periodically throws RESTRICTED PERFORMANCE, especially in wet weather, an now, after some energetic diving on a road made from potholes connected by tar
AIR SUSPENSION FAULT. I'm pretty sure the latter is a torn air bag, but I'd like to read the fault codes, and that's the problem.I have a Foxwell ODBreader with the Jaguar plugins, and a cheap ODB-to-wifi plug to read faults on my phone. Both of them hang when you plug them in and ask them to automatically read all faults. Some bits work, others don't. An hour with the Foxwell manually choosing one ECU at a time let me compile a list of those it can talk to. I think, given the diagrams in the 2008 Wiring Guide, that the CANBUS to SCP connection or the SCP bus is broken. (I'm not sure if the Foxwell talks to both buses, or uses the CANBUS to connect to the SCP, which I think uses a link in the Instrument Pack.)
Does anyone have any pointers or experience to share on sorting out this sort of problem?
I've found some documents that say the thing to do is measure resistance across the bus lines - working buses are basically a pair of wires with a terminating resistor at the end to prevent echoes, so if the resistance is wrong, it means open or short circuit, or corroded connections. I guess the process is to start with the ECU nearest the ODB socket (in wiring terms, not necessarily physical distance), and check its bus connections, working outward through the network until I find the problem or run out of patience and buy an iPace.