Earth Grounding points

Hi All,

I am trying to trace the ground points G201 (right side of IP, which I assume is instrument panel) & G202 (left side of IP) as per the 1996 System Wiring Mazda Miata.

This is the only wiring diagram I have been unable to find, and whilst it tells you most things it does not have a drawing of the earth locations.

I have removed the instrument cluster but can see no ground points, not sure if they should be there as the Miata is LHD.

I am trying to fit a panel dimmer switch, and from what I am being told the 1995 Eunos GLtd does not have the blue plug as part of the loom for some reason. The ground points I am looking for appear to be the ones responsible for grounding the panel lamps etc, so I am hoping that I can connect G201/2 to the switch and then to ground, which is what the original blue plug does.

Any help will be much appreciated

The grounds for the illumination lights are screwed to the metal dashboard reinforcement, they are at the bottom corners. I don’t have a photo of them screwed to the dash but the photo below shows the 2 wires, the ones on each side with the ring terminals on them.

Hi Roadster Robbie,
Many, many thanks, the photo shows it all.
Can I prevail on you for a little more info as you appear to know much more than I ever will?
Am I correct in believing that the GLtd does not have the blue dimmer plug as part of the loom?
Will as I hope removing the two ground wires and re routing the two black earth wires through the dimmer switch and then to earth have the desired effect?
I appreciate that this set up will also dim the interior cabin lights but I can live with that and if necessary can cut and re earth them.
The wiring diagram I have shows that the instrument panel & heater control lamps are all earthed to these two points, but it also shows a link wire to the boot lamp wiring earth although it also states that it is 1996 onwards. So I should be ok.
Not asking for a guarantee just your thoughts on the matter.
Thanks again

I’ve no idea if your G Ltd has the plug for the dimmer or not, my RS Ltd doesn’t I don’t think. I’d have to check the wiring diagram to see how the dimmer is wired, I can do that for you but not right now as I’m not at home. I’m not sure what else uses the same earth point, or if the illumination lights use both or one. The UK manuals for 200001 VIN onwards cars show 1.6 cars as not having the dimmer and 1.8 cars having a dimmer. NA cars didn’t have a boot light so not sure what that’s referring too. I’d always take US wiring diagrams with a pinch of salt when referring them to UK/JDM cars.

I get you info on the fitting of the reostat in the next day or so. What’s the last 6 digits of your VIN?

Hi, again many thanks.
Last six digits are 303532

This is the wiring diagram for the illumination circuit on a UK car I think you’ll have to use this as a guide and work from there. I’d guess the addition of the electric mirror switch on JDM cars meant the deletion of the dimmer switch. On UK cars the electric mirror switch was fitted on the centre console but on JDM cars it was in the cluster of 3 switches to the right of the steering column. I think you’ll have to assume yours is the 1.6 version. The dotted line represent differences between models, BP with the dimmer and B6 without, labelled near the 2 earth points. Other vehicle systems use the same earth points (power windows, cigar lighter, blower motor to name just a few) so you will have to work back though the wiring loom and find where the illumination earth is spliced into it, then break the circuit there.


Many thanks for all your help, the answer is in there somewhere.
Just need some fine weather to investigate now.
Will post back when & if I solve it.

Hi all,
Well another day of delving behind the instrument panel looking for these elusive earth connections has revealed nothing, or to be more precise nothing where they should be. However tucked away behind the large tubular cross member is what I presume is a white earth block, but without taking everything apart it is unreachable.
So time for a bit of lateral thinking, if I can’t detach the earth wire at the body can I break the circuit at the other end, ie by the instrument panel and the heater control unit. Yet more things to ponder and more exploring to be done.