FormulaDz92

Hey guys I just got through a long arduous electrical problem and I noticed something. My lights are dim when I first start my car but after a blip of the accelerator to about 2800 RPM they brighten up and stay that way. I installed a voltage gauge and confirmed that upon starting the car I am running at 12.2 Volts. After I blip the throttle I am at a solid 14.0 Volts and it stays that way.

I asked my friend who has an RB26 swapped s13 and he has the same exact problem (since forever) and thinks it normal.


Question: Are your lights dim when you first start your car then brighten when you blip the gas or start driving?


* My battery and alternator are good and have been recently changed.
* I'm not sure if I had this problem before all of the issues I just had and failed to notice. Maybe I'm just extra paranoid lately?

Thanks Guys!

*ANYONE WITH A 240SX CAN VOTE ON THIS QUESTION REGARDLESS OF CAR GENERATION OR MOTOR SETUP*

The make a poll option doesn't seem to be available to me so ignore that part. Just post Yes or No and if you can a brief explanation.

hanzbrady

Wow almost like the alternator works off of engine RPM or something.

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FormulaDz92

I'm not sure if that is sarcasm but if it is, why has this not been the case with my other shitty 90's cars? Additionally, when left running after starting, the voltage will still read 12.1 V 15 minutes later.

hanzbrady

If you spin something faster that generates power based on RPM what happens?

If you keep it at a steady idle RPM what happens?

If you compare the electrical systems between two different chassis and or manufactures with no "control" group is it a valid experiment?

The answer to all of this is RPM dictates power generation which generates the output of light in this case. Alternators at idle will maintain the voltage in a system, if you increase speed it will produce more voltage, if you go from increased speed to idle speed you will maintain the energy that was previously produced, eventually is will taper due to variables like drag or electrical draw but over a long period.

Arguing that this is some kind of issue because other cars don't do the exact same thing is invalid due to the fact that your comparing two at the least completely different electrical circuits and looking for an identical or similar result which wont happen due too many variables.

You could possibly change this behavior by just using a different type of alternator perhaps one not manufactured by Nissan since it's a strong possibility that all Nissan alternators have similar characteristics.

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travon47

Quit trying to be a smart ass and stick to sales at mazworx, it doesn't make you smarter than others... clearly. Yeah an alternator is based off rpm but they are designed to stay in between 13.5-14.5 idling or 10000rpm. He clearly has an issue with wiring or what ever and came on here for help, not bashing from others.

oewoko

I recently fixed this problem on my SR swap. When you turn on the ignition, does the battery icon on the dash illuminate? If not, that's your problem. Either a wire from the alternator is not attached, or the battery light is blown

In my case, I had one wire that was not attached to the harness

FormulaDz92

I will check this when I get home from work. Thanks

FormulaDz92

Just checked, when I turn the car on (but don't start it) the first 3 lights illuminate; but battery light (the 4th one) does not stay on. It flickers as I move the key from Accessory I position to Accessory II position but does not stay consistently on.

That said I am sure the battery is good. My other car is a Jeep Cherokee XJ and it conveniently has the same battery as the 240sx so I swapped them so I know that there are no problems with the battery because they should have occurred in the Jeep.

Thanks for all of the help so far

dbeiler

This is your problem, right here. Your charge indicator circuit is faulty.

The charge light MUST come on and remained illuminated until the engine/alternator is spinning fast enough to create electrical power.

When you turn the key on, the ignition switch must send power to the charge indicator bulb. The bulb will illuminate because the other terminal of the bulb is wired to the field coil connection terminal of the alternator. The alternator ground cable and alternator field coil effectively ground the charge bulb. When the alternator is at operational speed (and working correctly) the field coil will be at 12.7+ volts. The charge light bulb will then extinguish because both - and + sides of the charge bulb will be 12.7+ volts. Current will not flow when voltage is equal hence the charge bulb won't stay on.

You must diagnose the charge indicator circuit fault. Either you're losing voltage to the bulb through the ignition switch, or you're losing ground through the alternator side. I'd recommend testing the following components:
Fuse powering the acc portions of the ignition switch, ignition switch, charge indicator bulb, alternator ground, and any wiring between these components.

Please don't replace any parts until the issue has actually been diagnosed. Any proficient automotive technician (not some Pepboys smoe) could have it diagnosed in 5 minutes. You could've easily paid for that with what you've spent on three alternators.

Some important things to remember:
If the vehicle voltage is ever under 12.65volts, the alternator is not functioning. The battery is handling all the current draw.
Alternator output is regulated by controlling the amount of current through the field coil. Hence, a high current is used to maintain 12.7+ volts at idle, and low current to maintain 12.7+ volts at high alternator rotor speed. When idiots underdrive the alternator pulley, the alternator rotor speed can drop low enough to produce 0volts. I'll spare you my rant on that subject.

FormulaDz92

Ok great I'll check the charge indicator circuit.

Sometimes when I quickly remove my key, my dash lights stay on and my fuel pump constantly primes. Then I have to re-insert the key and repeat the removal process slowly and it's fine. I think this points to a faulty ignition switch. What do you think?

spooled240

You might need a new voltage regulator. You should be at 13.5V when the car is running.

FormulaDz92

I thought that the voltage regulator was internal to the alternator.

pacotaco345

The voltage regulator is the only plug on the alternator. Is your main alternator fuse (the 75A one) good? Mine was blown before and the none of the interior stuff would work til I revved the car once.

@hanzbrady I don't think you understand his problem. After he revs the car once he has good voltage, even at idle.

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FormulaDz92

The main 75 Amp Alternator fuse is good. With the car running (pre-reving) at 12.1 V everything works, interior lights, door bell chime etc. I may take a video and post it to Youtube to better illustrate my problem.

Also yes, after the initial rev, everything is all good. If this continues to be the case then i may just ignore the problem. If it worsens I'll obviously have to do something about it.

spooled240

what brand alternator did you get?

FormulaDz92

I usually buy re manufactured from Advance Auto, but in this case I splurged and bought a brand new one from Robert's and Son in Garfield NJ. They specialize in alternators, starters and the like.

FormulaDz92

I had the problem with the first one, then bought a remanufactured one from advance auto and had the same problem and then a third one, this time from Robert's and Son and had the same problem so I'm fairly certain it is not that. Here's a link to the original problem I solved before I came upon my current minor issue with the dim lights and voltage jump:

http://www.240sxforums.com/forums/s1...-charging.html

*sorry for the double post. It was an accident

tuzzio

Check your grounds. I know it sounds stupid. But, grounds do weird shit. Add another alternator to chassis ground and see if it helps.

FormulaDz92

Ok will do. What do you guys do for a battery tray liner? Sits between the battery and actual metal battery tray. Mine's pretty trashed

blkvrtswp

Trimmed large truck-style mud flap. Works great.

FormulaDz92

Awesome. Sounds like my kind of 'mod'

FormulaDz92

UPDATE: I took the car out for a drive and another car going the other way came into oncoming traffic directly at me causing my to karate kick the brake pedal which blew a brake line. Car is out of commission for the moment fixing that...