thesimondavey Posted January 30, 2018 Share Posted January 30, 2018 Hi all, I hope one of you can help please? I had my scuttle painted and had to remove the cut off switch from the panel. When I refitted the switch the engine management light was on. I disconnected the battery and check it all over and tightened up the bolts further as a bit loose and it went out. Started the 7 today and it’s back on again !!! Check and all over etc again but still on? Any ideas anyone please? Thanks Simon Link to comment Share on other sites More sharing options...
Dorset AR Posted January 30, 2018 Share Posted January 30, 2018 The engine management light function on a UK Sigma car doesn’t work. An electrical back feed to the tacho can illuminate the light dimly. To be honest it was probably always on, you just never noticed. The ODB will give you real time data but there is no fault log or code system in the car. There is a modification to sort this if it bothers you - speak to Ian at PT Sports Cars, they sorted mine after getting the detail from CC. Link to comment Share on other sites More sharing options...
ChrisC Posted January 30, 2018 Share Posted January 30, 2018 Having owned a UK spec 2011 Sigma 125 I know the MBE ECU can’t put on a check engine light, or talk OBDII. So is it stock? Can you post a picture or put the car on Easymap to see what’s happening? Link to comment Share on other sites More sharing options...
thesimondavey Posted January 31, 2018 Author Share Posted January 31, 2018 Hi and thank you both for your responses.The light is shining brightly ever since i tightened up all the bolts.And yes the car is a completely stock model. Link to comment Share on other sites More sharing options...
ChrisC Posted January 31, 2018 Share Posted January 31, 2018 Possible to get a picture of the light? - Will have a dig in the wiring diagrams when I know the light I am look at. Link to comment Share on other sites More sharing options...
Dorset AR Posted January 31, 2018 Share Posted January 31, 2018 Speak with CC or one of the good independent dealers, this is a well known issue. The odd thing is that it happens on some cars and not others. As I say, I had it on mine. Real time data can be obtained from the OBD port with Easymap but no fault codes although it might throw up a couple of dubious codes - this appears to not be unusual either. Have a look through past posts, this issue has been mentioned a few times. Link to comment Share on other sites More sharing options...
thesimondavey Posted January 31, 2018 Author Share Posted January 31, 2018 Thanks Christian. Link to comment Share on other sites More sharing options...
graemesmith Posted February 1, 2018 Share Posted February 1, 2018 Mine comes on Dim all the time and bright after I wash the car (which isn't too often). I spoke to Caterham and they confirmed that no stock Sigma has ever had this light enabled and that it is a known problem. They didn't offer to share any Mods with me though! Link to comment Share on other sites More sharing options...
ChrisC Posted February 1, 2018 Share Posted February 1, 2018 I suspect it's a difference between the engine and the chassis loom. The fuel gauge is wired from the Tacho (Y198) The connections from the fuel pump (and sender) are earthed in the engine loom, but are supplied from the chassis loom.So supply is Ignition Switch N47 to Joint N54 to N54 Fuel Pump Relay to YG166 to YG166 Fuse to YG167 to YG167 to Inertia Switch YG168 to Fuel PumpThe next Connection to the Fuel Pump is the sender level (but there is a strange extra blanked wire that could be causing the problem) GB148 to Joint with GB149 and GB150 (GB150 goes to the Tacho), (GB149 goes the engine loom through the large connector and back via a small connector to the chassis loom where is gets blanked) The next wire SG196 also goes to the large connector on the engine loom, and then to earth in the engine loom (BY51)The final connection is B10 to earth.If you have followed this so far you can see the Tacho is between the fuel gauge and the level sensor, and this sensor has two earths (engine and chassis) and a blanked off connection.To prove this you could remove anything from either the fuel level or fuel pump circuits. So that's inertia switch, relay, fuse or the pump from the fuel pump circuit or the fuel gauge. If the light goes out then earths (and that blanked off wire) is where I would look. Maybe someone local has a Sigma with this fault so I can dig deeper ;-) Link to comment Share on other sites More sharing options...
Dorset AR Posted February 1, 2018 Share Posted February 1, 2018 Or maybe you could just live with it safe in the knowledge it’s just a back feed and not a fault rather than mucking about and doing more harm? Link to comment Share on other sites More sharing options...
ChrisC Posted February 1, 2018 Share Posted February 1, 2018 Unfortunately new MOT rules (2018) dictate Engine Check light is a fail. Granted it says the light should come on and go off, I guess its easier to explain it has no engine check light if there is no light showing, than it is to try and explain its just a feed back loop lighting the light. All depends on how this rule is going to be seen. In truth if the earth difference is the problem all its going to be is cleaning a few connections and making sure the engine has a good earth, not the end of the world, but that’s a big IF Link to comment Share on other sites More sharing options...
thesimondavey Posted February 3, 2018 Author Share Posted February 3, 2018 Thanks all, i’ll Have a look at the car tomorrow if it stops raining and report back.thanks again to all.cheers Simon Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 4, 2018 Member Share Posted February 4, 2018 It would be great if you could pursue ChrisC's suggestions...Jonathan Link to comment Share on other sites More sharing options...
thesimondavey Posted March 8, 2018 Author Share Posted March 8, 2018 Hi all,a quick update.As the 7 has been parked outside I decided to remove the Rev counter and put it in airing cupboard at home just encase it has got damn, can’t remember what led me to that. I have put it back in the car after a couple weeks in the warm and the light is no longer on, so fingers crossed it’s sorted, but will report back when I have completed further testing Thanks again to all who responded to my issue.Kind regards Simon Link to comment Share on other sites More sharing options...
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