revilla Posted September 18, 2018 Share Posted September 18, 2018 I've been looking at Caterham's wiring diagrams for the EU2 engine, both VVC and MPi.I have a couple of questions if anyone with an EU2 car can help me please?Neither of the wiring diagrams show an MAP sensor. Is it correct that the EU2 engine did not run an MAP sensor?The EU3 wiring diagram has the MFRU fuel pump relay output wired directly to the grey plug to the main vehicle loom. Within the main vehicle loom the wiring diagram shows this as passing to Fuse 13, then the Inertia Switch and on to the pump. The EU2 wiring diagram has the Inertia Switch wired between the MFRU and the grey plug, so part of the engine loom rather than the main vehicle loom. Is this correct? The second point may well be relevant for people upgrading from EU2 to EU3, including an EU3 engine loom. My understanding was that the main vehicle looms were the same on EU2 and EU3 cars but this looks like it may not be the case. If there's no provision for the inertia switch on either EU3 engine loom or EU2 main vehicle loom, it will end up not being connected.PS: Jonathan, you sent me pics of your engine so I know it's EU2 ... and I know you like multimeters ... Link to comment Share on other sites More sharing options...
simon_h Posted September 18, 2018 Share Posted September 18, 2018 Normal EU2 engines had the MAP sensor built into the ECU, long bit of vac hose from plenum to ECU.VVC EU2 engines had a MAP sensor in the end of the plenum. Link to comment Share on other sites More sharing options...
revilla Posted September 18, 2018 Author Share Posted September 18, 2018 Ah yes that rings a bell now thank you. Link to comment Share on other sites More sharing options...
rj Posted September 18, 2018 Share Posted September 18, 2018 I am fairly certain that on a 1997 car, the inertia switch is in the main loom, not the engine ditto. Link to comment Share on other sites More sharing options...
revilla Posted September 18, 2018 Author Share Posted September 18, 2018 Thanks rj, that makes more sense. I think the main vehicle loom diagram is probably correct here for both EU2 and EU3 and the EU2 engine loom diagram is incorrect. Which really shouldn't surprise me! Link to comment Share on other sites More sharing options...
fordy Posted July 6, 2020 Share Posted July 6, 2020 Andrew, I'm just converting my car as you know from EU2 1.6K to EU2 1.8 VVC. I ran into the inertia switch issue as you described above and can clarify a few things here for posterity.On my 1997 EU2 1.6 K the inertia switch wiring is in the engine loom between the big grey plug and the MFRU (fuel pump relay). It changed with the introduction in 1998 of the VVC engine and is not on my 1998 VVC engine loom. Also confirmed off another 1998 car. Caterham moved the switch to the vehicle side of the big grey plug and the fuse box (fuel pump).As it stands my car may start without the switch in circuit since it's closed circuit in that yellow/green wire now and without the switch in either my vehicle or engine loom! I probably should splice a sub loom in though for safety sake and I may do it off the back of the MFRU since it's sat 4 inches away from the switch. Can anyone see any issues with that strategy? Link to comment Share on other sites More sharing options...
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