wierd ground makes car not start
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=105866
Printed Date: April 29, 2024 at 10:16 AM
Topic: wierd ground makes car not start
Posted By: klctexas
Subject: wierd ground makes car not start
Date Posted: July 02, 2008 at 8:42 AM
So about a month ago, I was driving and the power and ground wires came out of my cap, and touched each other. It did something to the spot where the cap was grounded, because now if I ground my amp there (it was previously grounded there), my car does not start. i recently had a fuel pump problem, had to replace that and run a new ground for it. What's wrong with my amp's grounding spot?
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Soldier: This is the worst part. The calm before the battle.
Fry: And then the battle is not so bad?
Soldier: Oh, right. I forgot about the battle.
Replies:
Posted By: KPierson
Date Posted: July 02, 2008 at 9:31 AM
What happens if you ground the amp somewhere else? I don't see a connection between grounding the amp and the car not starting - there has be be something else going on. ------------- Kevin Pierson
Posted By: DYohn
Date Posted: July 02, 2008 at 10:10 AM
If you shorted out your electrical system, are you sure something elsewhere in the vehicle is not fried? Did your fuse at the battery blow? How is the fuel pump problem related to the audio system? ------------- Support the12volt.com
Posted By: klctexas
Date Posted: July 02, 2008 at 10:34 AM
Yes, my main line fuse blew. The fuel pump problem and this are related because right after these wires touched, my car refused to start for about a month, till we got the new pump and determined that it needed a new ground wire. i have not been able to try and ground the amp somewhere else. https://www.the12volt.com/installbay/forum_posts.asp~TID~105207~PN~1 So the car is running fine again, except no subs. ------------- Soldier: This is the worst part. The calm before the battle.
Fry: And then the battle is not so bad?
Soldier: Oh, right. I forgot about the battle.
Posted By: DYohn
Date Posted: July 03, 2008 at 9:09 AM
What is the "amp grounding spot" you used and how is it related to frying your fuel pump? Did you ever get a multimeter? ------------- Support the12volt.com
Posted By: klctexas
Date Posted: July 03, 2008 at 9:39 AM
The ground for my amp is under one of the seatbelt bolts, underneath the back seat. It was working fine as a ground for over a year, now this happens. how is it related to frying my fuel pump? That's the answer I'm looking for, why does it make my fuel pumps ground not work when I ground my amp there?
-------------
Soldier: This is the worst part. The calm before the battle.
Fry: And then the battle is not so bad?
Soldier: Oh, right. I forgot about the battle.
Posted By: KPierson
Date Posted: July 03, 2008 at 9:41 AM
If the amp is hooked up does it work without the car running? What happens if you start the car then ground the amp? I'm guessing the problem here is your amp, not your grounding spot. You should verify that the amp actually works and then go from there. ------------- Kevin Pierson
Posted By: klctexas
Date Posted: July 03, 2008 at 9:45 AM
I'll try all of those things today when I get home, I'm at work right now. I hope nothings wrong with the amp, it just sat in my room for a month whlie the car was out of commission, and it was truckin it before that...
-------------
Soldier: This is the worst part. The calm before the battle.
Fry: And then the battle is not so bad?
Soldier: Oh, right. I forgot about the battle.
Posted By: DYohn
Date Posted: July 03, 2008 at 9:59 AM
I too suspect the amp is fried, mainly because of the major short you describe in the initial post. Plus, your seat bolt ground location is really a bad idea, and I suspect the reason it is related to the fuel pump is because you inadvertently cross-connected the amp through the fuel pump via a high-resistance ground location. That's why when you shorted out your system the fuel pump also fried. The two failures are related. Did you let the car repair shop know what really happened when they told you that you needed a new fuel pump? Take the amp to a reliable shop for bench testing to see if it is fried. Then either install it correctly (and get a multimeter so you can measure your ground return resistance) or get it installed by that reliable shop. ------------- Support the12volt.com
Posted By: klctexas
Date Posted: July 03, 2008 at 10:31 AM
How do I measure the ground return resistance? So hooking up a fried amp in a vehicle makes it not start? I've never heard of that.
-------------
Soldier: This is the worst part. The calm before the battle.
Fry: And then the battle is not so bad?
Soldier: Oh, right. I forgot about the battle.
Posted By: DYohn
Date Posted: July 03, 2008 at 11:00 AM
klctexas wrote:
How do I measure the ground return resistance? So hooking up a fried amp in a vehicle makes it not start? I've never heard of that.
Read the grounding stickies at the top of this forum. If the fried amp is shorting out your electrical system - or part of it, like the fuel pump due to an improper installation - then it could cause the car not to start. I suggest you need to get help from a professional since this is apparently a problem beyond your skill level. ------------- Support the12volt.com
Posted By: KPierson
Date Posted: July 03, 2008 at 11:07 AM
DYohn] wrote:
p>If the fried amp is shorting out your electrical system - or part of it, like the fuel pump due to an improper installation - then it could cause the car not to start. I suggest you need to get help from a professional since this is apparently a problem beyond your skill level.
That's what has me puzzled - if the amp was causing some sort of issue that is preventing his car from starting it should blow a fuse. The car shouldn't not start with the ground connected and then immediately start right up once the ground is removed. When you say the car won't start what do you mean? Will the starter crank but the motor won't turn over? Or does it not even crank? Also, what happens if the car is running when you ground the amp? ------------- Kevin Pierson
Posted By: DYohn
Date Posted: July 03, 2008 at 11:31 AM
Yea, I can't explain it either without putting my hands and meters on it, but that is what it seems is happening. Like I said, time to get a local pro on the case. ------------- Support the12volt.com
Posted By: klctexas
Date Posted: July 03, 2008 at 12:28 PM
Ok, ran a couple of tests at lunch. The amp works with the car not started. The motor will not turn over, it just cranks and cranks and cranks until I drain the battery. I have not yet been able to test wether grounding the amp with the car running will kill the motor. The car shouldn't not start with the ground connected and then immediately start right up once the ground is removed. => This is exactly what is happening. ------------- Soldier: This is the worst part. The calm before the battle.
Fry: And then the battle is not so bad?
Soldier: Oh, right. I forgot about the battle.
Posted By: DYohn
Date Posted: July 03, 2008 at 12:45 PM
klctexas wrote:
Ok, ran a couple of tests at lunch. The amp works with the car not started. The motor will not turn over, it just cranks and cranks and cranks until I drain the battery. I have not yet been able to test wether grounding the amp with the car running will kill the motor. The car shouldn't not start with the ground connected and then immediately start right up once the ground is removed. => This is exactly what is happening.
Then, like I said, you need to get someone local to help you. An automotive electrical shop might be in order. For whatever reason your amp is shorting out your fuel pump - maybe. ------------- Support the12volt.com
Posted By: klctexas
Date Posted: July 03, 2008 at 1:35 PM
I'll try grounding it when the car is running tonight, and then try grounding it to a different spot. If that does not work, then I will seek professional help, as suggested by the professionals!
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Soldier: This is the worst part. The calm before the battle.
Fry: And then the battle is not so bad?
Soldier: Oh, right. I forgot about the battle.
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