Car horn when trying to jump start

TheBDB

Diamond Member
Jan 26, 2002
3,176
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I just tried to start my 2006 G35 after 6 months of it sitting idle, and I believe my battery is dead, because it doesn't respond at all. I tried hooking it up to my friends car to jump start it, but when I connect the negative to the engine block, the horn starts going off. Is this some safety feature, or is it an indication that the battery is too far gone?
 

amdhunter

Lifer
May 19, 2003
23,332
249
106
It's your anti-theft system kicking in. When it goes off, disable it either by using the remote, or by turning the key to unlock your door. Give it around 30 seconds to a minute or so after the horn stops, and start your car.
 

TheBDB

Diamond Member
Jan 26, 2002
3,176
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So I got the horn to stop, but when I tried to jump it it attempted to start but couldn't quite make it. Should I just go buy a new battery or is there anything else to try first?
 

Zenmervolt

Elite member
Oct 22, 2000
24,514
34
91
Originally posted by: TheBDB
So I got the horn to stop, but when I tried to jump it it attempted to start but couldn't quite make it. Should I just go buy a new battery or is there anything else to try first?

You need to let it sit for 15 minutes or so with the cables connected and the other vehicle running to give the battery a little charge first.

That said, after 6 months (probably 4-5 months of that with the battery dead), you're pretty much certain to need a new battery anyway. If the car is going to sit that long, it's best to use a battery tender device.

ZV
 

TheBDB

Diamond Member
Jan 26, 2002
3,176
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Originally posted by: Zenmervolt
Originally posted by: TheBDB
So I got the horn to stop, but when I tried to jump it it attempted to start but couldn't quite make it. Should I just go buy a new battery or is there anything else to try first?

You need to let it sit for 15 minutes or so with the cables connected and the other vehicle running to give the battery a little charge first.

That said, after 6 months (probably 4-5 months of that with the battery dead), you're pretty much certain to need a new battery anyway. If the car is going to sit that long, it's best to use a battery tender device.

ZV

Yeah, I asked my roommate to start it up every couple weeks for a few minutes but I guess he forgot.
 

teddyv

Senior member
May 7, 2005
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New battery time. I travel a lot and when I have to leave my car at the airport for more than a week or so I use a solar batter tender - you can get them for like $20.
 

JulesMaximus

No Lifer
Jul 3, 2003
74,544
924
126
Originally posted by: Zenmervolt
Originally posted by: TheBDB
So I got the horn to stop, but when I tried to jump it it attempted to start but couldn't quite make it. Should I just go buy a new battery or is there anything else to try first?

You need to let it sit for 15 minutes or so with the cables connected and the other vehicle running to give the battery a little charge first.

That said, after 6 months (probably 4-5 months of that with the battery dead), you're pretty much certain to need a new battery anyway. If the car is going to sit that long, it's best to use a battery tender device.

ZV

Or buy some decent quality jumper cables.
 

Zenmervolt

Elite member
Oct 22, 2000
24,514
34
91
Originally posted by: JulesMaximus
Originally posted by: Zenmervolt
Originally posted by: TheBDB
So I got the horn to stop, but when I tried to jump it it attempted to start but couldn't quite make it. Should I just go buy a new battery or is there anything else to try first?

You need to let it sit for 15 minutes or so with the cables connected and the other vehicle running to give the battery a little charge first.

That said, after 6 months (probably 4-5 months of that with the battery dead), you're pretty much certain to need a new battery anyway. If the car is going to sit that long, it's best to use a battery tender device.

ZV

Or buy some decent quality jumper cables.

Even with my 4-gauge cables it can take a couple minutes if the battery's really flat.

I was assuming that he was using real jumper cables and not those little toy ones that can be had for $10 with their own carrying case. I'm not sure those would charge my cell phone. :p

ZV
 

fstime

Diamond Member
Jan 18, 2004
4,382
5
81
Same happened here, just have someone stand next to you ready to hit the unlock button with you connect to the battery.


Anti theft systems...
 

05StangConvert

Junior Member
May 22, 2016
1
0
0
2005 Mustang Convertible- Dead battery due to travel. Key fob Nor Key unlock disarming car horn alarm when jumper cable s attached. Next plan is to try silkster /f150online.com. Thanks for any helpful recommends.