Ground Testing

[jrwalte 10+ year member]

I'm trying to test the ohm resistance between my battery ground and the ground in the trunk. I think I may have a grounding issue. I always had a little alt whine but after about a week of usage my pico fuse popped on my 800PRS while driving down the road which made the alt whine unbearable. I did the pico fuse trick to resolve it and now I get absolutely no noise, but I'm thinking I have a bad ground to have caused it to pop to begin with.

In addition, I'm thinking I may have a bad ground or 'not good enough' because at times my amps will shut themselves off. At first I solely thought it due to a lack of power issue (80amp stock alt and Kinetik 1400 running 1900RMS). But the memphis st1500d amp will cut off at low volume as well. In addition, even when I have the memphis remote wire disconnected my front eclipse 4100 amp (which never did this before I connected the memphis) has started to fade out and sometimes completely shut off, to then turn back on a few seconds later. Does the memphis still draw power if the remote wire is disconnected? Yes, I have a HO alt on order. Best I could get was 180amp.

I can't imagine the stock alt not being able to handle the Eclipse alone. I previously had the eclipse and a PG Ryval 800RMS amp with no power issue ever. This just started when I installed the Memphis (I always had the alt whine issue even with the PG).

First off, to make sure I'm doing this right, I set the meter to ohm and connected the red lead to a monster speaker wire that I ran to the battery negative. Then I connected the black lead to my ground distro block.

I'm getting an ohm reading of zero. But if I start the car my ohm reading then constantly jumps typically around 1-2 ohm but up to 8. Should it be like that? i've done the big three and I'm running 0g to my trunk. I have a 0g ground wire going to a distro block to my two amps at 4g.

Also, my voltage at the bat was 12.73 while the trunk was 12.67. When I started the car the bat was 14.18 and the trunk was 13.17. Is that bad?

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[jrwalte 10+ year member]

hmmm....yeah. I think it's my trunk ground //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif I take off my trunk bottom to look at my grounding spot and the streetwires grounding block is loose as a SoB!!! //content.invisioncic.com/y282845/emoticons/eek.gif.771b7a90cf45cabdc554ff1121c21c4a.gif When the bass would it or I hit a bad bump in the road...bye bye ground. How stupid! All this time and effort...and I never looked assuming it was still tight. I'm going to to kick that friends *** who said those screws would be fine //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I got self tapping metal screws I'm going to try now.

 

[jrwalte 10+ year member]

ok, now I'm really going to kick his ***. He went behind me and changed the screws. two of the three holes had clean drill holes with machine screws in them. The drill holes were the same size as the screw! Those were the two that gave out. The bottom 'wood' screw below was the only one holding!

And thanks to his drilling the holes are too big for a self tapping screw. I'll have to make a new ground spot, plug in those holes, or see if I can reach from behind on that spot and bolt it.

 

[helotaxi 5,000+ posts]

If you can get behind the machine screws, put nyloc nuts on them and call it a day.

 

[jrwalte 10+ year member]

I had to pick a new spot. Where I originally placed it only 1 screw was accessible from behind.

Nyloc nuts? Not familiar with those. I went and got all stainless steel machine screws, lock washers and nuts. I also bought the red lock tight compound from autozone which is meant to resist vibration. I was able to tighten it extremely tight with no one holding the screw on the other side (it wasn't slipping). Is that adequate?

 

[BoomBoomBoy 10+ year member]

I got self tapping metal screws I'm going to try now.

Never ground any car electronics with screws, PERIOD! They'll always loosten and they **** as a mechanical fastener. I guarantee you this will happen everytime.

Either ground to an existing bolt or weld stud or drill and bolt.

 

[BoomBoomBoy 10+ year member]

I had to pick a new spot. Where I originally placed it only 1 screw was accessible from behind.
Nyloc nuts? Not familiar with those. I went and got all stainless steel machine screws, lock washers and nuts. I also bought the red lock tight compound from autozone which is meant to resist vibration. I was able to tighten it extremely tight with no one holding the screw on the other side (it wasn't slipping). Is that adequate?

Nyloc nuts = nuts with an nylon insert. The nylon insert acts as a locknut.

Loctite will not work on screws. It's intened usage is with machine threaded fasteners.

DON'T USE SCREWS UNLESS YOU LIKE WHAT ALREADY HAPPENED TO HAPPEN AGAIN.

 

[jrwalte 10+ year member]

Nyloc nuts = nuts with an nylon insert. The nylon insert acts as a locknut.
Loctite will not work on screws. It's intened usage is with machine threaded fasteners.

DON'T USE SCREWS UNLESS YOU LIKE WHAT ALREADY HAPPENED TO HAPPEN AGAIN.

Maybe you misunderstood my post? I'm not screwing to the metal. I drilled through the metal and used a stainless steel lock washer and nut with the loctite. I'm not stupid like my friend. I saw what needed to be done.

My question was, is a lock washer the same as the nylon nut or should I change it?

 

[BoomBoomBoy 10+ year member]

Maybe you misunderstood my post? I'm not screwing to the metal. I drilled through the metal and used a stainless steel lock washer and nut with the loctite. I'm not stupid like my friend. I saw what needed to be done.
My question was, is a lock washer the same as the nylon nut or should I change it?

Both intended to do same thing. Either will be fine.

 

[jrwalte 10+ year member]

Great news! I was just driving around 40+ minutes and everything is good. I cannot believe this whole issue has been due to a loose ground. You have no idea how long I've been trying to figure this out and it's blown 3 Pioneer pico fuses (one 880 and 2 800s). I know to never take the ground location for granted again if I have issues.

After driving around I think I want to upgrade the kicking friend's *** status to killing. I bought a HO alternator and kinetik 1400 (almost $600 total) because the voltage was constantly dropping to the 12s and the memphis would keep shutting off. But this whole drive it stayed constant around 13.7-13.9 and never went in the 12s and of course never shut off. I even played some blurbs from a bass CD and it didn't drop below 13.5 while idling. This is still with my STOCK alternator. The HO is on the way! AHHHHHH

Because the system worked with my old amp, I never thought of a grounding problem. But when I replaced my 3 JL 8W3 with a single RD Elite 15" and put this memphis amp with it, the sub hit so **** hard that the ground was shaken loose //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I'm still kind of shocked that my 80 amp alt seems to be handling the memphis (1500RMS) and Eclipse (400RMS) without issues even at idle. I still don't mind upgrading the alternator, but it sucks to know I could have waited and probably just allowed this system to overrun the stock for 6 months or so before it gave out.

And this friend of mine wants to open up a shop and do installs. I think I'll need to crush his dreams //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif This was my first time messing with a car audio system and I did a much better job then him. Reading this forum for 3-4 months will do that //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Great info here.

 

[BoomBoomBoy 10+ year member]

You're welcome.