Fuse under hood 7.5AMP "ALT. S" question
05-29-2006, 08:18 PM
#1
Fuse under hood 7.5AMP "ALT. S" question
This fuse is under the hood in the rectangular box on the right hand side of the battery. It is labeled "ALT. S" and is a 7.5A fuse. Yesterday I realized this fuse was broken. Some of you may remember my threads about my voltage being high, mid to high 14s often 15.0 well the voltage certainly came down and started settling around 14.6-14.7V after replacing the fuse today, I realized now my voltage is mid 13's, I was just wondering if this fuse had any correlation with the alternator, and or the charging system.
05-30-2006, 07:46 AM
#3
Junior Member
Join Date: Apr 2006
Location: Blacklick, ohio
Posts: 25
If you have not gotten your alternator replaced, call nissan and ask them if your car had the alternator recall done. The diode in the alternator are faluty and can cause a fire. My alternator was smoking on and off and I got it changed for free from the dealer. Try this first.
05-30-2006, 10:54 AM
#4
Well I'm sure the alternator is fine, it was just purchased from the dealer months ago. So I'm assuming it doesn't have a bad diode. I'm just really curious as to what that fuse does and why the voltage would drop nearly 1 volt.
05-30-2006, 12:43 PM
#9
Oh my bad haha.
Mine blew and tripped the batt and brake light. It blew when I was connecting the connector on the alternator that recharges the batt(2pin). So it does have something to do with the voltage regulation and charging. And you are fine with 13.x volts. Get the charging system tested at autozone since it puts a load on the system and checks it.
Mine blew and tripped the batt and brake light. It blew when I was connecting the connector on the alternator that recharges the batt(2pin). So it does have something to do with the voltage regulation and charging. And you are fine with 13.x volts. Get the charging system tested at autozone since it puts a load on the system and checks it.
05-30-2006, 12:54 PM
#10
Np man 
, are you talking about the rectangular connector, it's the only connector on the alternator, I believe it's a 3 prong connector, but the alternator only has 2 prongs. Yeah my voltage is consistent, no fluctuations or pulsations but nevertheless I will get it test today, keep in mind I'm running a system, HIDs, etc.
, are you talking about the rectangular connector, it's the only connector on the alternator, I believe it's a 3 prong connector, but the alternator only has 2 prongs. Yeah my voltage is consistent, no fluctuations or pulsations but nevertheless I will get it test today, keep in mind I'm running a system, HIDs, etc.
05-30-2006, 01:18 PM
#12
No infact the audio or headlights have very little effect on the output, the voltage will drop a hair when rolling up the windows or when the fans kick on which is normal but they shoot right back up to the mid 13's, it's not reaching towards the 14s at all. What do you think? Maybe an issue? It's an essentially brand new OEM Nissan alty from a dealership. Only a few months old.
05-30-2006, 08:14 PM
#15
I went to autozone it was between 13.8-13.9 directly at the battery. The amps however were not going above 4.0 the tech at AutoZone said the amps should be 60 I don't know if that's true or not though. But pulling out the fuse the "ALT. S" fuse did raise the volts back up to the upper 14's. What do you think about the amps though?
05-31-2006, 01:21 PM
#21
100% chingon
Join Date: Oct 2005
Posts: 1,003
OH DOG not another battery voltage thread 
The so-called 'Tech' is an idiot.
4 amps charge is reasonable when the car is running. Without lights or anything else you're only powering the ignition and the fuel pump, basically.
60 amps? Put 60A into the battery for just a little while and watch the thing explode. Battery terminal volts on charge should be 13.8 nominal, depends on brand and age.
Originally Posted by HarrisH
I went to autozone it was between 13.8-13.9 directly at the battery. The amps however were not going above 4.0 the tech at AutoZone said the amps should be 60 I don't know if that's true or not though. But pulling out the fuse the "ALT. S" fuse did raise the volts back up to the upper 14's. What do you think about the amps though?
4 amps charge is reasonable when the car is running. Without lights or anything else you're only powering the ignition and the fuel pump, basically.
60 amps? Put 60A into the battery for just a little while and watch the thing explode. Battery terminal volts on charge should be 13.8 nominal, depends on brand and age.
05-31-2006, 01:23 PM
#22
Originally Posted by clive
OH DOG not another battery voltage thread
The so-called 'Tech' is an idiot.
4 amps charge is reasonable when the car is running. Without lights or anything else you're only powering the ignition and the fuel pump, basically.
60 amps? Put 60A into the battery for just a little while and watch the thing explode. Battery terminal volts on charge should be 13.8 nominal, depends on brand and age.
The so-called 'Tech' is an idiot.
4 amps charge is reasonable when the car is running. Without lights or anything else you're only powering the ignition and the fuel pump, basically.
60 amps? Put 60A into the battery for just a little while and watch the thing explode. Battery terminal volts on charge should be 13.8 nominal, depends on brand and age.
Are you kidding me? You know the alternator pushes over 100amps around 1500-2500... High output alternators can push 100amps at idle.
06-01-2006, 06:43 AM
#23
Should I just get a voltmeter and test the amps? I don't think they're low though I mean the car runs JUST fine I'm just not clear as to why they're machine would register a number so low.
06-01-2006, 07:06 AM
#24
Originally Posted by HarrisH
Should I just get a voltmeter and test the amps? I don't think they're low though I mean the car runs JUST fine I'm just not clear as to why they're machine would register a number so low.
Yeah I don't see how the car runs fine. I wouldnt worry about it. As along as the car is charging under a load and stuff. Maybe the Autozone machine was messed up.
06-01-2006, 07:22 AM
#25
Yeah 4 amps seems way to low for the car to be running lol, are voltage and amperage related? Is there a formula in which I would be able to obtain the actual amps in correlation with the volts?
06-01-2006, 11:02 AM
#26
Originally Posted by HarrisH
Yeah 4 amps seems way to low for the car to be running lol, are voltage and amperage related? Is there a formula in which I would be able to obtain the actual amps in correlation with the volts?
Ohms Law.
06-02-2006, 12:59 PM
#27
So guys here's the RULE! If you think you're having charging problems, PLEASE CHECK YOUR FUSE! The past 3 years I've been here I've read a plethora of threads that are related to charging, overcharing, undercharging problems/issues/concerns and not ONCE was this stupid fuse mentioned.
11-13-2018, 08:34 AM
#28
Newbie - Just Registered
Join Date: Nov 2018
Posts: 2
Two pin harness
The white wire with red trader stripe goes to the battery through the alt s (s for sensor) fuse. It sends the battery voltage to the alternator to sense the charge condition of the battery. A low voltage at the battery tells the alternator to increase the charging voltage . When the fuse is blown there is no voltage, which of course is low voltage caus ing the alternator to max out, 15.2v for my aap Reman, which triggered my brake and battery lights to flash due to this condition. The other pin, black and yellow wire goes to the idiot light.
11-14-2018, 01:19 PM
#30
Newbie - Just Registered
Join Date: Nov 2018
Posts: 2
Huh?
I have no idea what that means. But when I was looking up help on my problem this thread came up and it helps me. I added some things that I also found out that we're not in this thread that may help somebody else.
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