My engine is from a 2001 R25 1.4 K-series. My auto electrician has located some wires that, according to the manual, are for the rough road sensor. My question is: do I actually have to have a rough road sensor connected for the ECU to work, or can I just tape up the ends of the wires and forget about them?

Second question - what exactly is a rough road sensor and how could I fit it if I did need one?

Thanks in advance

Rough road sensor is fitted with the MEMS 3 system, it prevents the misfire detection fault code in the ecu being triggered by rough roads. If you are using a MEMS 3 in theory you need it connected I am not sure exactly how it functions could be a simple mercury tilt switch.

[Edited on 29/7/05 by britishtrident]

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Originally posted by britishtrident
Rough road sensor is fitted with the MEMS 3 system, it prevents the misfire detection fault code in the ecu being triggered by rough roads. If you are using a MEMS 3 in theory you need it connected I am not sure exactly how it functions could be a simple mercury tilt switch.

[Edited on 29/7/05 by britishtrident]

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I had a quick look at the 25 MEMS manual the bad news is the sensor signal comes from the front LH ABS sensor (even on cars without ABS) it is a 0 to 5 volt square wave at 800 pulses per mile.

I don't know the effect of the ECU not getting signal, I know it will set an OBD p code but don't now if it wll trigger the malfunction warning lamp or trigger a limp home mode --- I suspect it won't but I don't know.

Keep us posted on how you get on --- the MEMS3 system is significantly different from the more usual MEMS1.9 but it introduces more interesting features such reading OBD data and tweaking the fueling and ignition advance via the EOBD socket.

Spoke to a Rover dealer parts department - the bloke there first of all tried to say there was no such thing as a rough road sensor. Then came back and said it's the same as an ABS sensor and is £113+VAT! Thought it "probably" would be OK just to complete the circuit so the ECU can't identify a broken circuit... not sure about that. I think I'll try first with nothing on the wires (and kept separate. If that doesn't work, I could try completing the circuit.

I have also searched on the MG Rover forum, but nothing useful so far.

Also tried Blatchat (Cateringvan) but their search facility is down

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Originally posted by britishtrident
I had a quick look at the 25 MEMS manua...l

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RAVE CD with all the Rover manuals in pdf format usually can be found on Ebay for a fiver or less :-)