Blown 100amp MAIN fuse

SP BLING · 20-07-2009, 09:41 PM

Hey guys,

I went to finally start my car tonight after 18 months, but as I was connecting the battery up, it sparked and blew the main 100amp fuse located in the engine bay fuse box.

For history of my car, see my worklog: http://www.astinagt.com/forums/showthread.php?t=13821. The electrics were ok before the repairs as the car would start.

I'm not sure what really caused this, but the key was in the ignition and turned on as is the engine was running (forgot to check before connecting the battery). Normally I would think that this wouldn't blow the main fuse - especially as there was no real current draw. None of the wiring loom has been touched/cut/modified.

If it wasn't the key, then maybe the alternator or stater motor is shorting out? The car has a brand new battery as well.

Has anyone held of this happening before?!?!?!

Mic

project.r.racing · 20-07-2009, 09:52 PM

did you try to put the positive terminal back on while the negitive was attached?

SP BLING · 20-07-2009, 09:54 PM

Yeah, I put the negative on first, and was connecting up the positive.

project.r.racing · 20-07-2009, 09:59 PM

negitive should be the 1st off and last on.

you probably just earthed it replacing the terminals the wrong way around when you had drain from the ignition being on.

did it shoot some sparks while you were replacing the positive terminal?

Ghoru · 20-07-2009, 10:04 PM

yeh NEVER take off/put on positive first, i didnt blow a fuse as my mate took most of the kick lol

SP BLING · 20-07-2009, 11:09 PM

Yep - plenty of sparks!!!

No worries though. I'll go down to the local wreckers in the morning and grab a new fuse or 2.

NaughtyGT · 20-07-2009, 11:10 PM

^^^! Only time this ever happened to me was when my Hyundai sat for months. Used a massive battery to start it & it sparked a beauty & blew same fuse your talking about. I had to then use a standard 60 amp fuse til' I got proper one later. I was glad it wasn't an ECU! You didn't use too big a battery did you?

SP BLING · 22-07-2009, 01:07 AM

Grabed a few fuses this morning from the wreckers.... Tried again connecting it up the proper way with ignition key off and it still blew.

After a quick look through the Electrical diagrams, the only device functional through the Main fuse with the ignition off is the Alternator. After a quick look from underneath, we had connected up the main positive lead minus the plastic spacer meaning that the cable was grounded to the alternator body.

We quickly made up a spacer and get it all sorted! No more shorting out anymore. Thanks all for your help!!!!

20-07-2009, 09:41 PM	#1
SP BLING AstinaGT Regular Join Date: Feb 2008 Location: Quakers Hill, NSW Car: Mazda 3 & BA Astina Posts: 277	Blown 100amp MAIN fuse Hey guys, I went to finally start my car tonight after 18 months, but as I was connecting the battery up, it sparked and blew the main 100amp fuse located in the engine bay fuse box. For history of my car, see my worklog: http://www.astinagt.com/forums/showthread.php?t=13821. The electrics were ok before the repairs as the car would start. I'm not sure what really caused this, but the key was in the ignition and turned on as is the engine was running (forgot to check before connecting the battery). Normally I would think that this wouldn't blow the main fuse - especially as there was no real current draw. None of the wiring loom has been touched/cut/modified. If it wasn't the key, then maybe the alternator or stater motor is shorting out? The car has a brand new battery as well. Has anyone held of this happening before?!?!?! Mic __________________ 2005 \| Mazda 3 SP23 Hatch \| Sunlight Silver [daily driver] 1997 \| Mazda 323 Astina Hatch \| Fridge White [soon to be daily driver]

20-07-2009, 09:54 PM	#3
SP BLING AstinaGT Regular Join Date: Feb 2008 Location: Quakers Hill, NSW Car: Mazda 3 & BA Astina Posts: 277	Yeah, I put the negative on first, and was connecting up the positive. __________________ 2005 \| Mazda 3 SP23 Hatch \| Sunlight Silver [daily driver] 1997 \| Mazda 323 Astina Hatch \| Fridge White [soon to be daily driver]

20-07-2009, 10:04 PM	#5
Ghoru Senior Member Join Date: Jun 2009 Location: Rockhampton Car: '92 BG Astina Sp Posts: 999 View Photos By: Ghoru	yeh NEVER take off/put on positive first, i didnt blow a fuse as my mate took most of the kick lol __________________ BG Astina - work in progress.... Scooters are like fat chicks, fun to ride until your mates find out... NOS is like a hot chick with AIDS, you know you wanna hit that,your just afraid of the consequences... http://www.eveonline.com/

20-07-2009, 11:09 PM	#6
SP BLING AstinaGT Regular Join Date: Feb 2008 Location: Quakers Hill, NSW Car: Mazda 3 & BA Astina Posts: 277	Yep - plenty of sparks!!! No worries though. I'll go down to the local wreckers in the morning and grab a new fuse or 2. __________________ 2005 \| Mazda 3 SP23 Hatch \| Sunlight Silver [daily driver] 1997 \| Mazda 323 Astina Hatch \| Fridge White [soon to be daily driver]

20-07-2009, 11:10 PM	#7
NaughtyGT Senior Member Join Date: Jun 2009 Location: Baxter, VIC Car: Sooby B4 - Astina SP parting out Posts: 2,447	^^^! Only time this ever happened to me was when my Hyundai sat for months. Used a massive battery to start it & it sparked a beauty & blew same fuse your talking about. I had to then use a standard 60 amp fuse til' I got proper one later. I was glad it wasn't an ECU! You didn't use too big a battery did you? __________________ My Shepherds in the Avatar haha "When the power of love overcomes the love of power, the world will know peace" - Jimi Hendrix

20-07-2009, 09:52 PM	#2
project.r.racing Senior Member Join Date: Sep 2004 Location: n/a Car: n/a Posts: 10,929	did you try to put the positive terminal back on while the negitive was attached?

20-07-2009, 09:59 PM	#4
project.r.racing Senior Member Join Date: Sep 2004 Location: n/a Car: n/a Posts: 10,929	negitive should be the 1st off and last on. you probably just earthed it replacing the terminals the wrong way around when you had drain from the ignition being on. did it shoot some sparks while you were replacing the positive terminal?

22-07-2009, 01:07 AM	#8
SP BLING AstinaGT Regular Join Date: Feb 2008 Location: Quakers Hill, NSW Car: Mazda 3 & BA Astina Posts: 277	Grabed a few fuses this morning from the wreckers.... Tried again connecting it up the proper way with ignition key off and it still blew. After a quick look through the Electrical diagrams, the only device functional through the Main fuse with the ignition off is the Alternator. After a quick look from underneath, we had connected up the main positive lead minus the plastic spacer meaning that the cable was grounded to the alternator body. We quickly made up a spacer and get it all sorted! No more shorting out anymore. Thanks all for your help!!!! __________________ 2005 \| Mazda 3 SP23 Hatch \| Sunlight Silver [daily driver] 1997 \| Mazda 323 Astina Hatch \| Fridge White [soon to be daily driver]