graemesmith Posted June 16, 2019 Share Posted June 16, 2019 Sorry to start an old thread again. Just wondered if anybody had come across a fix for the dimly glowing Check Engine Light on SIgma cars? Mine is a 2017 310SIt is not actually an active system on UK cars but a lot of them experience a dim glow, sometimes quite bright if its been raining. Most of the time you can't see it in bright light so I've just been happy driving with the knowledge that it is just a random electric thing.Unfortunately the 2018 MOT regs state that if a car has a MIL it needs to be operative. Self build and Kit cars don't require a MIL so that's good.The problem will be trying to convince the MOT center that the dimly glowing MIL is not in fact fitted! It does not come on during self test which helps the case but I can just imagine the conversation "well it glows so it's there, it doesn't self test so it's broken - Major Category fault'!I've read quite a few reports on the Internet about it being fixed by a 'mod' which ranges from a simple resistor to a circuit board in the loom including quotes that the advice has come from Caterham. As with all things internet none of these reports are validated and no one can actually post the details of the 'fix'.Any one have more info or indeed experience of a recent MOT withe the light glowing dimly?I could always try and find an open air MOT center! Otherwise it looks like dismantling the Tacho and removing the LED. Link to comment Share on other sites More sharing options...
K7 VCT Posted June 16, 2019 Share Posted June 16, 2019 Hi, are you anywhere near oxford, if so i can recommend a decent Mot centre Link to comment Share on other sites More sharing options...
Jim 123 Posted June 16, 2019 Share Posted June 16, 2019 Has anybody tried asking CC for a general letter explaining the situation with their cars which can be shown shown, if needed, to an MOT tester? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 16, 2019 Member Share Posted June 16, 2019 The rules are new but I can't remember or find any discussion.Otherwise it looks like dismantling the Tacho and removing the LED.Have you got the appropriate wiring diagram? The same effect might be achievable outside the instrument.Jonathan Link to comment Share on other sites More sharing options...
graemesmith Posted June 17, 2019 Author Share Posted June 17, 2019 Just got the official fix from Caerbont. There should not be a wire connected to the Tacho at the MIL pin location. If there is it will cause the light to illuminate. Mine had the wire connected. I cut it at the Tacho end and the Dim MIL problem went away. I assume the length of wire in the loom is suficient to pick up a low conductive voltage and dimly light the bulb.Anyway, problem solved.Unlike the other internet posts which report to have fixed it I'm happy to share the info. DO THIS AT YOUR OWN RISK!!!!The 12 way connector has 2 rows of 6 pins. The black one is Pin 7 - bottom right looking at the connector face. The one to the left is pin 8, the MIL pin. It was Grey/Red on mine. I just snipped it a bit up the cable in case I got it wrong as its easy to crimp a cable back together.Might not be the fix for all models but it works on the EET3-1B32-97B (30D145A) Caerbont Tacho as fitted to a January 2017 Sigma.Update: Pins run clockwise from top left 1 to 6, then bottom row furthest right is 7 and furthest left is 12. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 17, 2019 Member Share Posted June 17, 2019 Good work.Did you find a diagram that matched your car?The diagrams I have for Sigmas have a 20 way connector. I found the following for R400s but the wiring isn't as you describe.ThanksJonathan Link to comment Share on other sites More sharing options...
graemesmith Posted June 17, 2019 Author Share Posted June 17, 2019 That one is wrong as well. I don't have a wiring diagram, just went with what Caerbont described. The B 37 looks like Pin 7, the earth so the one to the left on the bottom row should be Pin 8 although the colour is wrong in the diagram. If it helps, I think the BU157 is the correct pin.My numbers run clockwise from the top left. Pin 1 top left, Pin 6 top right, Pin 7 bottom right, Pin 12 bottom left. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 17, 2019 Member Share Posted June 17, 2019 ThanksJonathan Link to comment Share on other sites More sharing options...
graemesmith Posted June 17, 2019 Author Share Posted June 17, 2019 I've updated my main post to include the Pin convention! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 23, 2019 Member Share Posted June 23, 2019 Pins run clockwise from top left 1 to 6, then bottom row furthest right is 7 and furthest left is 12.Thanks.I wrote to Caerbont asking if they had the pinouts and any notes. I got a reply but it didn't answer the question. Then no reply to my follow-up.JonathanPS: I'm still surprised that we don't seem to have discussed this in detail before... Link to comment Share on other sites More sharing options...
JonPivo Posted July 25, 2023 Share Posted July 25, 2023 Hello, Following two annoying conversations at MOTs about the dimly glowing engine check light, I decided to follow the method and remove the wire linked to the tacho. Seems to have worked for me. The wire in question was brown/grey on my 2019 310R, and I removed it from the connector rather than cutting in case I got the wrong one!On the wiring diagram it is wire BU153.Thanks to original poster for sharing! Jon Link to comment Share on other sites More sharing options...
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