A Caterham Seven Blog

  • ECU Diagnostics – part 13.3 : MBE-ISOTP

    SUMMARY We now understand the communications protocol used by Easimap (the Windows software supplied by the ECU manufacturer) and can use it to ask the ECU for whatever data the car has to offer. We can then manipulate the responses we get back from the car and format them to make sense to us. TL;DR…

  • ECU Diagnostics – part 13.2 : OBD-II

    The OBD-II diagnostic protocol is well defined and information about it can be found in On-board Diagnostics. It’s a mish-mash of many diffrerent standards, both physical and electrical, that I’ll refer to as OBD-II. There’s also a complete breakdown of the Services and PIDs (see below) that can be found in On-board Diagnostic PIDs. I’ll talk…

  • ECU Diagnostics – part 13.1 : MBE-Broadcast

    The simplest of the three Caterham OBD port diagnostic protocols we know about is what I’ve called MBE-Broadcast. As soon as the car is put into ignition switch position 2, the ECU starts to spit out a this stream of data on the CAN bus. Unlike the OBD-II protocol and the MBE-ISOTP protocol, this a…

  • ECU Diagnostics – part 13 : Three Diagnostic Protocols in the MBE 9A4 ECU

    This one’s just a short post to introduce the next three posts. In our investigations of the MBE 9A4 ECU we’ve found three different diagnostics protocols supported on the OBD port. The following three posts will summarise what we’ve learnt about each protocol and will be updated with new information as it becomes available. 13.1…

  • ECU Diagnostics – part 12 : OSI 7 Layers for Caterham Diagnostics

    ECU Diagnostics – part 12 : OSI 7 Layers for Caterham Diagnostics

    Communications protocols are often called protocol stacks… they’re layers, or stacks, of different protocols… one layered on top of the other from lowest level (hardware/physical) to highest level (software application). This is where the OSI 7 Layer model comes in… it standardises how we think about the layers and allows us to talk about where…

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