Strange Exige grounding issue - LotusTalk - The Lotus Cars Community
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post #1 of 2 (permalink) Old 10-14-2018, 02:40 PM Thread Starter
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Strange Exige grounding issue

So, in the process of a minor radio upgrade, part of a larger project I will detail in another thread, I bought a new Pioneer to replace a 3 year old pioneer.

Same wiring harness, although because Pioneer inexplicably give random number values to the wires in their harness connector that have no relation to the pinout, I chased my tail for a while on that.....

So I plug the new receiver into the old harness, turn on the ignition, and...nothing.

I poke around and realize the fuse has blown. I see nothing amiss replace the fuse, it blows again.

Put the old receiver in, works fine.

OK, rare as it may be, bad unit.

I remove it and all of a sudden my rear view cam is not working[totally different circuit]
My add on oil gauges are acting bizarrely. They are on the same circuit as the camera

After some examination with the meter, the gauges are grounding through the parking lights so they die if you turn the lights on.

I am staring at the wire grounding the gauges[I drilled and tapped a hole in the dash structure behind the switch panel, and one for the camera on the passenger side in the same place]
Yet there is no ground.


They have worked for 2 years.........

Definitely 2 volts difference between that ground and the door hinge....

So, after much poking and prodding I come to the realization that the dash support has lost its ground.

I realize Lotus does not use it as a grounding point, but I am staring at the rivets and screws holding it to the chassis. I tap a #8 into the horizontal channel exposed under the dash end of the sill panel and run a hefty ground.

Gauges are fine, camera works


Whatever happened with the radio, it somehow popped whatever strand was grounding the support, I guess

The chassis is all anodized, so surface contact does not mean an electrical contact, but this is odd

Guess there is a reason they don't ground to that part ....
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post #2 of 2 (permalink) Old 10-14-2018, 04:03 PM
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Originally Posted by exigegus View Post
. . .
The chassis is all anodized, so surface contact does not mean an electrical contact, but this is odd
. . .
For those who aren’t clear what @exigegus is alluding to, the anodized surface of aluminum is an electrically non-conductive oxide. So he was relying on punching through the anodize where the screw tapped into the aluminum, then through the rivets or other fasteners holding everything together on to a chassis ground connected by wire to the battery.

Maybe the holes in the structural aluminum were punched or drilled prior to anodizing, then rivets disturb the anodize just enough to provide a minimal electrical connection to some other well-grounded structural member. Over time, riveted joints could flex (still held secure by adhesive) and the electrical continuity is degraded.


2011 Lotus Elise SC
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