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Green Beastie 453R

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was having a few problems with the gauges on a new 420R firstly rev counter, going off dial and now speedo flicking.  I guess as VDO gauges they are all stepper motor. Unfortunately I could not replicated fault at dealer. They also said they could not do a diagnostic, which I found as odd.  while speaking to a fellow owner at Brands last week, they said there is a plug loosely strapped to the steering column which I found. I decided to do some more research and found this. 


It looks like access is blocked. Any idea of path forward ?  I understand that Luke Stevens can access maps for his rolling road work and he is local to me. 



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Its a plug that happens to be an OBD plug as its a standard thing. The ecu doesn't have any OBD that can be read by a scan tool, this doesn't apply to the Suzuki or the EU versions though, you can only use the MBE program to observe things. The dash faults wouldn't be able to be seen via that either as they are just standalone gauges.

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The symptoms you describe to me appear to be localised electrical gremlins  (e.g. maybe a poor earth to the instruments etc.) if it's affecting more than one instrument assuming the car is running perfectly fine atm.

Access to the ODBC/ECU will confirm the rest of the car is OK but not what's causing the gauge problem.

 Unfortunately there's no single diagnostic plug-in tool I'm aware of to identify the sort of problem your describing. If  I was faced with the problem with my own car it would probably be a process of elimination using a combination of multimeter testing/tracing wires, checking earth mounting points and if necessary swapping out components as a last resort to eliminate them from causing the issue i.e. it could be something dead simple or turn into a bit of a mare

In your case since the car is newish, back to the dealer to be sorted under warranty would be my route. To help them, try to video any "evidence" of the problem/record under what circumstances when it happens etc. to aid the investigation.



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I have seen the Tacho read incorrectly before, it was a US kit builder with a 360R.  That was solved by correcting the dip switches on the Tacho.  In that case the Tacho was under reading. 
OBD is present on on some models, EU spec cars and UK SuperSport  1600 example, but I haven't seen it on 420R.

Your speedo flicker will depend on the age, either pre 2016 where the sensor is a little unreliable, or post 2016 where the sensor needs to run closer to the trigger wheel than the previous version. 

Both sound simple DIY fixes, but if Team Leo's is near maybe drop it into them for assistance. 


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Luke at Team Leo's can certainly access ECU's and carry out mapping of the engine. I recently had my 2019 420R re-mapped by him.
As others have said I don't think the problems you have encountered are anything to do with the ECU.

I have had problems with my speedometer becoming erratic and this was due to the reluctor ring on the driveshaft moving and the teeth not being seen by the sensor, the gap between the sensor and reluctor ring is also key. That's where I would look with regard to the speedometer.

I'm not sure about the rev counter. I guess if both issues occur simultaneously then that points to a common problem not related to the reluctor ring/sensor, but I'm not sure what that may be. 

I'm sure Luke would be able to solve it, but if it's still under warranty the original dealer should really sort it out. As I'm sure you know intermittent problems are more difficult so trying to record when the problem occurs - high speed/low speed or high revs/low revs, etc., may help dealer replicate issue. Good luck.

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Hi Green Beastie, That was my website you linked to and I hope it was helpful. There's also a set of easier to digest articles in LF from June/July of 2020.

To your point about stock ECU's being locked - they are locked in the sense that the internal maps cannot be updated, they are write-locked. But, I understand there are some people that can get around that.

If you think I got anything wrong in LF or on my blog then please let me know by PM and I'll take a look.

In any case the information that can be read from the ECU over the OBD port is quite limited and won't show you faults with dials etc., unless Caterham have changed things since my car was built in 2017 :-). Like others on this thread have said, it sounds like the OS rear speed sensor needs some adjustment to sort the flickering speedo (I did mine again only a few weeks ago because I was getting flickers again). I can't offer any suggestions for the rev counter - but on my car the rev counter is not connected to the CANBUS and so not visible on the OBD port (the Sigma engines have CANBUS tacho's but as far as I can tell that's not the case on the Duratec's - though I'm going to check that again now I've done a lot more on Caterham electrics since I wrote those articles).

I'm not saying anything different to those who posted above, but wanted to let you know you can contact me if you have any questions about my site or articles.


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Yeah my UK Super Seven 1600 has a standard OBD-II port behind the rubber grommet above my right knee.

I got the cheap Foxwell scanner from Halfords and it works fine! Gives you both live data readings and stored error messages.

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