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Alternator and battery problem on 240sx

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hi guys, i know this is a 240 problem but you guys are very knowledgeable.


so ive had a problem in the recent past with getting my car started. Sometimes id turn the ignition and the car would turn on just fine, other times id get a click from my starter but the car wouldn't start. So i changed my battery terminals and the problem with fixed for about a week. Until the problem arose again.


I left the car sitting for about a week, tried starting it and it did not start. So i figured i had a draw. So i removed the negative terminal from the negative post and hooked up a multi meter in between and started pulling fuses and testing with a test light. I found that i had a draw in my alternator fuse. I figured that this was a bad diode. So i left the car sitting for another month with the battery hooked up, took the battery to get slow charged and the battery was bad. So ive replaced the battery.


My question is... is the alternator FOR SURE the problem? does it need to be replaced? Thanks, sorry if i sound ignorant. educated me.

Edited by datzenmike
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I may be way off base but...... Is is a standard transmission? Nissan has a starter relay (25230-89981) that was real good at letting the car start when it wanted to and not starting when it needed to. It is a blue relay that looks like 2 relays fused together.....about2" x 1" and will have 2 connectors attached to it. Wish I could tell you where it is located or if your ride even has it...but aI no longer have access to Nissan catalog........

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Since you have one, the next time it won't start, smack it a good one.....if it starts that is your bitch, and it is a might bit cheaper than an alternator.


ps...you can usally get away with smacking that relay for about 6 months, then you have to replace it.


Hope that is your deal




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so ive had a problem in the recent past with getting my car started. Sometimes id turn the ignition and the car would turn on just fine, other times id get a click from my starter but the car wouldn't start.





The clicking starter might also be a problem internally in the starter. If the starter clicked, then the relay did its job already.

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soooo there was an aftermarket stereo installed by the PO that i pulled. hopefully that was part of problem, i figured there may have been a draw from that. also, i hooked up a test light between the neg terminal and post and found that when i pulled the alternator fuse that the test light turned off. Sooo im thinking thats a possible problem right there. I left the battery hooked up over night and im gonna go back in the morning to see if it was sucked dry. wish me luck!

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alright so i removed a stereo that was installed by the PO. i left the battery hooked up to the car over night. i just went out and put a multi meter to it and got about 12.31 volts with the motor off.


Also, I hooked up my test night between the neg terminal and neg post. I pulled fuses until the light went out. When i pull the gray alternator fuse in the fuse box above the battery it turned off.


So does this mean i still have a problem with my alternator even though it doesn't look like i have a draw any more since i removed the stereo? edit: looks like i still do have a draw, 12.31 v is low correct? Alternator looks like more and more the problem


Also, I am still having problems getting the car started. The first 3 times it just gave me everything except a turnover to start. Then the 4 time it started up FINE. Turned it off again, then tried to turn it on. nothing. then tried again and it started up fine! Ill check all my grounds today... but any other suggestions? take out the starter for a load test?

Edited by 240sx123
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I could not start one of Big Daves 521s. to make a long story short the battery was bad. cause the alternator was bad.

I used a test light and pulled the volt reg and then also pulled the alternator wire then the test light when out(NO draw of power). after that I left the scence of the crime but I think Dave or somebody got a new alternator and new battery.


Now I dont know your whole situation but you at least have to isolate the stereo and Alternator and also really need to ck to make sure this battery can still hold a charge and draw a good load on there. Then maybe even that a seliniod could be bad on the starter. But you more or less got it figured out already on how to trouble shoot.


Just ck the connections and clean them again, esp the battery conncetions


My yellow 510 has a click click every now and then but I assume since I swapped a starter already its a low voltage across the key swithc and I could fix this with a Hot start relay. But since I dont drive this all that much I dont worry about it. A hot start relay is a Light Black Box relay wired up striaght to the battery so when I turn the switch a straight 12volts goes righ to the starter selinoid.


But i assume since you have a newer car it already has this in the system somewhere.

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12.31 v is low correct?
It means nothing by itself.

* To check the draw use the Ohmeter 30A scale

* To check the voltage, start the engine idle it at 1200 rpm. It should be 13.5 to 15.0 volts. If is is low the battery may be partially dead. Or the alternator may be bad.

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i went to work with the battery hooked up to the car, then got back and tested 8 hours later with my multimeter before i started the car.... 12.63 volts!!! wooo hoooo! when i started the car it was around 14 and when i reved it increased to about 14.5!!! soooo it looks like the culprit of the draw was the stereo.


but the test light is still on when i bridge it between the neg post and terminal and it doesn't come off till i unplug the alternator fuse. whats that all about?


also, the starts ALMOST everything single time on the first try. there have been a couple times though that ive turned the key with nothing once or twice THEN i get it to start strong. sounds like starter? i just replaced it a year ago but i guess it could be out again...


and about testing the draw, i turn it on ohmeter 30A when the car is off and on and make contact with the pos. and neg. post correct?

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Does this car have a clock in there? maybe thats the draw.


When cking the draw using a meter youll set the meter up on AMPS scale.I pick the biggest setting then work your way down. Hopfully its in the milliamps scale.This prevents it from pooping the meter if using a Old alalog meter. But new digital version prevent the meter from popping.


Youll do the same thing as the test light by putting it in series.When doing this Amp ck. Put meter inbetween the battery post and the battery cable.



make sure the doors are closed ectt so a dome light dont come on buzzer ect......

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