Finding Earthing points

Cooper · Post by **Cooper** » Sun Aug 13, 2006 8:42 pm

Hello. We have an intermittent problem where the power windows, wipers and heater blower do not work. We suspect that there is a common earthing point for these, and that the wire contact is loose or needs cleaning. However we don't know where to look. Does anyone have any ideas? We have wiring diagrams that show the earth as being the black wire, but not actually where the thing is earthed to.

Thanks
Kate & Michael

Euen · Post by **Euen** » Sun Aug 13, 2006 9:54 pm

On the 96, the earth for the wiper motor is a lug under one of the mounting bolts for the motor. I don't recall if there were any other earth cables going to that point but I don't think that there were.

I don't know which year your car is, but the diagram for the 96 shows that although they are individually fused, those 3 circuits all come from the "RUN" position on the ignition switch on a common Blue/Red cable. That seems to be the only common point.

Good luck
Euen

Blues Boy · Post by **Blues Boy** » Mon Aug 14, 2006 6:58 am

I had this same exact thing happen on my previous '90 mx-5. It turned out to be related to the ignition switch as Euen mentioned. On my car it seems that the metal contacts had become dirty. The next time it happens, jiggle the key up and down a bit to see if your wipers or blower come back on. If so, then it's definitely related to the ignition switch. Mine was fixed by just twisting the key back and forth quickly between OFF and RUN a few times. This cleaned the contacts enough to make sure they worked properly. Hope your's is as easy to fix...

Post by **zorruno** » Mon Aug 14, 2006 12:12 pm

on 13/08/2006 8:42 p.m. Cooper wrote:

Hello. We have an intermittent problem where the power windows, wipers
and heater blower do not work. We suspect that there is a common
earthing point for these, and that the wire contact is loose or needs
cleaning. However we don't know where to look. Does anyone have any
ideas? We have wiring diagrams that show the earth as being the black
wire, but not actually where the thing is earthed to.

Thanks
Kate & Michael

Hi Guys,

I'd put money on the Ignition switch being the culprit. The US Miata
listers think that it becomes more common with a heavier set of keys
being used regularly - but I think it is just more likely just a wear
thing that happens to some and not others.

Unbolt the ignition switch, take it apart, and give it a good clean with
electrical contact cleaner or white spirits. Shouldn't be too hard a job.

cheers

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