# Diagnosing Electrical Drain- Elec b Circuit (Fuse # 24)



## dmiga (Aug 19, 2006)

Hi,

I have a 1997 Nissan Pathfinder LE that has had a parasitic drain on the battery for a while. If I left the car unstarted for more than three days, the battery would be dead (which is a brand new battery). I decided to start the throubleshooting of a parasitic drain.

I first checked to see if thee were any lights remaining on (glove box, etc) but all appeared normal. I hooked up an ammeter between the negative terminal of the battery and the cable. Sure enough, it was drawing about 155mA with the ignition off and vehicle at rest with no lights on. After removing FUSE # 24 from the fuse box on the driver's side, the current drain immediately dropped to about 45mA.

I can see that the "security system" is no longer blinking (actually, it never seemed to work as I have tested it before) and the door chime no longer works either (when you leave your keys in the ignition and open the door). So, does anyone know what else is on this circuit???

I have removed the 7.5A fuse from #24 (ELEC B) and I have had no other parasitic drain problems so I am pretty sure I have hte circuit. If anyone knows what else is on iths circuit, I can test each device to sii which is causing the 100mA drain. I have a feeling it is the security system. If so, can I simply disable the security system and replace the fuse?

Thanks all!


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## littlefish (Jul 1, 2006)

*Battery Drain*

First of all be sure you have the correct manual (schematic) for the vehicle. If the incorrect manual is used, you can chase ghost. Using an ampmeter on the negitaive terminal, is not a bad way to test, but does not always let you now which fuse is carrying how much current. Do you have a meter that can be used to place the probes into the fuse blade terminal? That way you can test each fuse to see MA drain, or if there is any drain at all on that circuit with the ignition off. If you find current flowing, highlight the fuse on the schematic with a yellow highlighter and note the MA drain. Follow the circuit out, and un-plug each item to verify the drain goes away. It could be a defective diode in a relay that has failed and is leaking current past. I have never measured current drain on an alarm circuit, but seriously doubt it should be enough to kill a bettery in 3 days. Also my Honda has been left at the airport for 2 weeks and fired right up. That was in the middle of December. However, I did have an Isuzu pickup that had a defective relay in the seatbelt circuit that would kill a battery in 5 days. I found the problem by tracing it with a MA meter on each leg of the circuit drawings. Make sure you have the correct drawing and you should find it. Good Luck!


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## dmiga (Aug 19, 2006)

*Parasitic Drain*

Where do you think the best schematic could be obtained from? I took a look at a Hayes shematic yesterday and it smply said that the fuse 24 was the fuse for a Data Link Connection (GST) ... whatever that is.

I basically did pull and check every fuse and relay with the ignition off to see if the current dropped and the only one that was significant was this fuse 24 (ELEC B). 

You are right, I need to get a good shematic and recheck everything on that circuit. Are there better shematics than the ones found in the back of a Haye's manual?

Thanks for your reply.


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## golfer (Aug 21, 2006)

The 155ma parasitic drain reading you got is not outrageous considering that modern vehicles have electronic control units for things like security , key less entry , stereos , etc. which all have constant power wiring that draws from the battery without the key on.

Has this " new " battery been load tested ??


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## dmiga (Aug 19, 2006)

*Parasitic Drain*

The new battery came from Sears. They checked the battery and charging system of my vehicle but I am not sure if it was load tested. I'm sure it was.

Understandable, there are a lot of normal current drains that exist with the vehicle ignition in the OFF position. But from the research that I have done, anything >50mA appears to be suspiciously high. 

http://www.mightyautoparts.com/pdf/articles/tt63.pdf#search="parasitic battery drain"

The vehicle can now sit for a week and start just fine. So, I am assuming that there is something on fuse 24, ELEC B, that is causing hte 100mA drain. I would still like to know what is exactly on this circuit besides the security system and, if possible, how I can test for the correct drain of that circuit.


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## golfer (Aug 21, 2006)

Hope this helps;

according to a schematic these items are on the circuit for fuse 24 :

AUDIO

P/ANT

MUTI BUZZER

THEFT

A/T

PNP/SW

MIL/DL


Good luck.


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## dmiga (Aug 19, 2006)

Thank you.

I've been runningit without fuse 24 (ELEC B) and have seemingly stopped the large drain on the battery. My radio still works, I have no power antennae, but my SERVICE ENGINE SOON light just cameon last night.

I am assuming that it has to do with one of the other devices. I am assuming that A/T is automatic transmission but I do not know what PNP/SW or MIL/DL is.

I guess I'll figure it out if you are kind enough to send the schematics.

Thanks again!


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## golfer (Aug 21, 2006)

Usually the MIL usually stands for Malfunction Indicator Light and DL would probably be the Dash Lights.

That's not the case here because the service engine light ( other name for the Malfunction indicator lamp ) is on you say. 

In this case MIL / DL is for the *Data Link *as I discovered with some more research..

The PNP / SW is the *Inhibitor Relay * in the starter ciruit.

From what I can tell so far is A / T is part of the Speedometer , Tach as well.

Hope this helps.


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## golfer (Aug 21, 2006)

One thing you can try is to check what the actual parasitic drain on the circuit for fuse 24.

Here's what to do with the fuse removed:

1 Set the multimeter to *D.C. amps *

2 put one lead of the meter on one side of fuse socket

3 put other lead from meter on other side of fuse socket


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## dmiga (Aug 19, 2006)

*Parasitic Drain*

Well Golfer,

Thankf=k for your help! I do believe we finally found the drain.

A while a go I noticed that my power antenna was not working and I checked it out. I guess the circuitry and/or the motor was bad so (I thought) I disconnected the power to it. I did not replace it because it was too expensive and I still receive all of my favorite stations without the antenna being up.

I tested the amperage through fuse 24 and it was high (about 110mA) and then unplugged the power antenna and it went down significantly (10 - 12mA).

So, thank you very much for all of the schematics and info on this circuit. I am confident that it is resolved.


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## golfer (Aug 21, 2006)

dmiga said:


> Well Golfer,
> 
> Thankf=k for your help! I do believe we finally found the drain.
> 
> ...


You're welcome , glad I could help .


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## rogitts (Aug 25, 2010)

*ELEC B fuse battery drain*

I have a 2001 Pathfinder without a power antenna and I have this same battery drain...I have a brand new battery and it runs down overnight....Does anyone know what this problem is and can it be fixed?


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