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Author Topic: Grounding points inside cabin/under dash  (Read 1781 times)
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PK1
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« on: September 29, 2016, 06:56:44 PM »

Basic question related to the installation of my Hydra:

The harness has a couple of extra ground wires that the manual recommends connecting to ground points (although optional.)  Are there any ground points in the vicinity of the Hydra (behind glove box) or under the dash somewhere, or do I need to take the wires to the engine compartment?
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2005 VR MSM, #1254 of 1428
FM exhaust
Rest of FM LE kit + FM radiator and stage II fan in boxes awaiting installation
SilverMiataRacer
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« Reply #1 on: September 29, 2016, 07:04:14 PM »

The best ground point would be to connect the ground to the grounding strap on the head.  The question should be is the ground you need to use a chassis ground or should you be tieing it into another electrical ground.
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Larry

4 Miatas but who's counting!!   Cool

White Knight    1991 Crystal White   #99 CSP
Silver Bullet     1992 Silverstone     #17 SM2  FM I+ Turbo  (Gone but not forgotten)
Honey B          1992 Sunburst Yellow #99 SM2 J.R. M45
Whooosh         2004 Titanium MazdaSpeed MX5  #403 of 4000
Subie              2006 Steel Gray WRX STi Cobb Stage 2 (Gone but not forgotten)
No name yet    2008 Velocity Yellow Tintcoat Z06 Corvette
No Name yet    2014 Ashen Grey Metallic Camaro 2SS 1LE

“There are only three sports: mountain climbing, bull fighting, and motor racing. All the rest are merely games.”
– Ernest Hemingway
PK1
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« Reply #2 on: September 29, 2016, 08:05:48 PM »

Thank you Larry, admittedly this is not an area of expertise for me.

The written instructions aren't specific as to the type or location, they just say use a good ground.  In an email exchange with Jeremy @ FM he mentioned that any good ground I can find should do provided that I have tested with a meter for ground quality, so I thought I'd pose the question here to see what the options are and what others have done.

If I follow your advice, would I then install both ground wires to the same location, which is the grounding strap on the head?  I'll need to go find the strap on the head...
Otherwise, following Jeremy's suggestions, I'll need to temporarily run a wire from the battery's negative terminal to the area under the dash to see which bolt has the same resistance b/w it and the battery and then compare to the resistance I would get from connecting (shorting) the meter leads.  Whichever bolt or connection point that has the same resistance to the battery than shorting the meter leads is a good ground point.  Am I understanding the process correctly?
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2005 VR MSM, #1254 of 1428
FM exhaust
Rest of FM LE kit + FM radiator and stage II fan in boxes awaiting installation
SilverMiataRacer
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« Reply #3 on: September 29, 2016, 08:08:34 PM »

You've got the right idea.  Me, I like engine grounds.  The strap should be on the back of the head on the drivers side, IIRC.
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Larry

4 Miatas but who's counting!!   Cool

White Knight    1991 Crystal White   #99 CSP
Silver Bullet     1992 Silverstone     #17 SM2  FM I+ Turbo  (Gone but not forgotten)
Honey B          1992 Sunburst Yellow #99 SM2 J.R. M45
Whooosh         2004 Titanium MazdaSpeed MX5  #403 of 4000
Subie              2006 Steel Gray WRX STi Cobb Stage 2 (Gone but not forgotten)
No name yet    2008 Velocity Yellow Tintcoat Z06 Corvette
No Name yet    2014 Ashen Grey Metallic Camaro 2SS 1LE

“There are only three sports: mountain climbing, bull fighting, and motor racing. All the rest are merely games.”
– Ernest Hemingway
PK1
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« Reply #4 on: September 29, 2016, 08:26:33 PM »

Cool, thanks.  More work under the dash...  afro

There are two circumstances in which I am particularly happy I'm not a big guy:

- On regional jets (I travel a lot)
- When working on this car!  I'm still sore from the contorted positions required to run the vacuum hose to the cabin last night...
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2005 VR MSM, #1254 of 1428
FM exhaust
Rest of FM LE kit + FM radiator and stage II fan in boxes awaiting installation
SilverMiataRacer
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« Reply #5 on: September 29, 2016, 08:39:53 PM »

Any time you have to work under the dash fold the top down and remove the seat.  You can lay on your back under the dash with your feet on the rear deck and even me, at my size and age, can get under there.  I did once try to do work under the drivers side without removing the seat and was stuck under the steering wheel for awhile.

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Larry

4 Miatas but who's counting!!   Cool

White Knight    1991 Crystal White   #99 CSP
Silver Bullet     1992 Silverstone     #17 SM2  FM I+ Turbo  (Gone but not forgotten)
Honey B          1992 Sunburst Yellow #99 SM2 J.R. M45
Whooosh         2004 Titanium MazdaSpeed MX5  #403 of 4000
Subie              2006 Steel Gray WRX STi Cobb Stage 2 (Gone but not forgotten)
No name yet    2008 Velocity Yellow Tintcoat Z06 Corvette
No Name yet    2014 Ashen Grey Metallic Camaro 2SS 1LE

“There are only three sports: mountain climbing, bull fighting, and motor racing. All the rest are merely games.”
– Ernest Hemingway
Black Mica 05
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#1068/1428 11/9/04


« Reply #6 on: September 29, 2016, 10:14:24 PM »

I did once try to do work under the drivers side without removing the seat and was stuck under the steering wheel for awhile.

On the driver's side...Its easier to get positioned under the dash than it is to get out.
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When I die, I want to go peacefully like my Grandfather did, in his sleep...not screaming, like the passengers in his car
SilverMiataRacer
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« Reply #7 on: September 29, 2016, 10:15:40 PM »

I did once try to do work under the drivers side without removing the seat and was stuck under the steering wheel for awhile.

On the driver's side...Its easier to get positioned under the dash than it is to get out.

Oh yea I figured that out after I was stuck there and no one else was around.
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Larry

4 Miatas but who's counting!!   Cool

White Knight    1991 Crystal White   #99 CSP
Silver Bullet     1992 Silverstone     #17 SM2  FM I+ Turbo  (Gone but not forgotten)
Honey B          1992 Sunburst Yellow #99 SM2 J.R. M45
Whooosh         2004 Titanium MazdaSpeed MX5  #403 of 4000
Subie              2006 Steel Gray WRX STi Cobb Stage 2 (Gone but not forgotten)
No name yet    2008 Velocity Yellow Tintcoat Z06 Corvette
No Name yet    2014 Ashen Grey Metallic Camaro 2SS 1LE

“There are only three sports: mountain climbing, bull fighting, and motor racing. All the rest are merely games.”
– Ernest Hemingway
PK1
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Posts: 186


« Reply #8 on: September 29, 2016, 11:25:38 PM »

I did once try to do work under the drivers side without removing the seat and was stuck under the steering wheel for awhile.



Aye!  Not good... noted!!
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2005 VR MSM, #1254 of 1428
FM exhaust
Rest of FM LE kit + FM radiator and stage II fan in boxes awaiting installation
barmato
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Posts: 743


« Reply #9 on: September 30, 2016, 03:02:09 AM »

I connected the extra hydra ground to some of the metal bracing behind the glovebox.  They tested good when I hooked it up but come to think of it I have been having some misfire issues. Maybe it's time for me to revisit that ground.
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PK1
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Posts: 186


« Reply #10 on: September 30, 2016, 03:25:48 AM »

From what I've read the misfiring is an issue with Hydra period, although in a post I recently read some were claiming that reverting back to r85 firmware from r87 improved the issues. Mine is loaded with r87, we'll see when I finish installing it.

That said, let me know if examining/changing grounds addresses the issue.
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2005 VR MSM, #1254 of 1428
FM exhaust
Rest of FM LE kit + FM radiator and stage II fan in boxes awaiting installation
barmato
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Posts: 743


« Reply #11 on: September 30, 2016, 10:23:55 AM »

That was me Smiley
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PK1
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Posts: 186


« Reply #12 on: September 30, 2016, 11:02:35 AM »

LOL!! And I'm preaching to the choir  Smiley.

So is this a new misfiring issue? Let me know if you resolve it, I'm curious as to what's causing it.
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2005 VR MSM, #1254 of 1428
FM exhaust
Rest of FM LE kit + FM radiator and stage II fan in boxes awaiting installation
TheBigChill
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Posts: 555


« Reply #13 on: September 30, 2016, 12:36:00 PM »

Under the dash, maybe the easiest ground location is the metal frame surrounding the fuse panel (drivers side, by your left knee).

Barmato:  There's no reason that using that location should cause a misfire, unless the ground in general was poorly done.  Both the engine and chassis grounds should maintain an equal ground potential.  As Larry said though, using the engine grounds is perfectly fine too.
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barmato
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« Reply #14 on: September 30, 2016, 03:47:27 PM »

I don't think it has anything to do with that either but its worth a quick look.
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