Ground issues?

[SK400]

Greetings,

 

I have a 2013 R400 superlight and since the very first day, I’ve been having issues with my speedo and ACES shiftlight systems. Essentially:

1) The speedo won't read or work past 45 mph (stops reading, needle fluctuates and then drops to zero)

2) The ACES change lights won't detect the Engine RPM (there is power but no RPM reading). When I look on the ACES website, one of the most common reasons is because of poor ground.

 

I've been trying to figure it out but to no avail (super frustrating). Obviously, it shows how little knowledge I have of electrical systems overall.

 

As an aside, I asked caterham and they said that most of the new speedos had issues with grounds.., ok great. They sent me a special instruction sheet suggesting to ground the speedo sensor on the frame member closer to the sensor to improve ground. This worked for Red Duck here in CT with a new CSR but did not work for me.. I’m still having the same issues. (and yes, God knows how many times I've adjusted the sensor gap +/- the nominal 1 mm required gap)

 

Any thoughts on how to diagnose or investigate the issue? Any thoughts on the root cause?

I much appreciate your help.

THANKS!

[Sean]

A sketchy ground on the instruments is common. Prevailing wisdom on BC is to loosen or remove the nut on the main ground point behind the dash where the wiper motor bolts in (behind passenger side knee trim panel, which will need to be removed first and re-installed after), scrape some paint/powder coating away at the point on the frame where the threads protrude to expose bare metal for a solid grounding path, and re-install/re-tighten nut. I did this, but added a dab of conductive grease as well, and it did the trick on my 2006 car.

 

Best of luck.

Edited April 20, 2015 by Sean

[jlumba81]

If nothing else works you can always run a wire from that sensor ground straight to the battery negative post.

[SK400]

Alright then. Thanks for the tips. I love try this Friday or Saturday and report back. Thanks a bunch!

[drew...]

SK400 - Can you post the "special instruction sheet" from Caterham regarding the speedo ground?

[SK400]

SK400 - Can you post the "special instruction sheet" from Caterham regarding the speedo ground?

 

Here's what I have

 

 

WRNOT 572 - Speedometer sensor ground wire installation(1).pdf

[SK400]

Not having much luck. Do you have a sense of the Max resistance I should see between an instrument and the ground using an ohm meter to determine if I have a bag ground?

Thanks

[coffee break]

Is there a way to check the functionality of the tack on another motor?

[Zona]

I think you should prefer fixing your wire straight to the battery and make it run, that's it.