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View Full Version : SR20 Electrical/Alternator Problem.


Tomatosoupp
08-18-2013, 03:52 PM
The other day I was doing 4th gear pulls on the freeway, hopped off the freeway, drove home, and as I am pulling into my parking space, my car bogs down and dies.

I let my car cool down, ate some dinner, then head back outside. I rolled my car out of my parking space and jumped my car. it took a moment to get it jumped but then it fired right up. As soon as I take the cables off, my car then died again.

Frustrated, I parked my car and left it for the night. The next morning I pull out a battery pack and jump my car. Starts up fine and idles fine again, then we take the battery pack off and it dies again. Now I think its my alternator.

I pull out a volt meter and check my battery with no connections and it is putting out 7v. I have a 12 volt Oddysey battery so I get a charger and charge it all the way up. It took about 14 hours to get a full charge.

After Charging the battery, I pull off my alternator. After pulling off my alternator off I run a bench test and it fails for charging. I look for a used SR20 Redtop alternator. I find a used one from a local import shop in boise. I have it tested before I put it on and it fails for going up to 15.8v . I call the shop and they tell me to put it in anyways because there should be a problem since it is a newer generation Alternator. I install the alternator and sure enough I am right it is putting out 15.8v when running a volt meter while the car is running.

This is where the wierd part comes in. My electronics go crazy, my boost gauge is not working, the battery light is flashing and making a ticking sound, my doors are randomly locking and my window wipers are randomly wiping.

I turn off my car, and take off the alternator. I read about installing a KA24det alternator so I buy one and drill out the top hole, swap the pulleys and bolt it on. It fits up fine and everything connects fine. After installing the KA24 Alt I turn on my car and notice the battery light is off but the doors and windows wipers etc. are still going crazy. I pull out the volt meter and notice the volts are only at 11.8 with lights on at 1000RPM. This tells me the Alt is not charging. I turn off my car and check all my grounds. The grounds look fine.

I not look through my fuse box to find that the 75amp fuse is blown. I will replace this tomorow and hopefully everything is fine, but I dont belive the blown fuze would cause my electronics to go crazy.

Prior to all this the car has been driven for 6000+ miles after the SR swap with no problems.

Any Ideas Welcome, Please no hate as I am still new to Silvias.

Thanks Guys.

soundboy
08-20-2013, 01:51 PM
Ok. First thing your alt needs to show 12-14v. The car should cut off if disconnected from the battery. This shows the alt isn't working.

Start the car and make sure that when you disconnect the battery that the alt still shows the 12-14 v.

Also is the alternator charging wire properly connected? Personally I'd upgrade it to either a 0g or 4G wire. Normal car amplifiers wires will work. Google the big 3 upgrade

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Tomatosoupp
08-20-2013, 04:17 PM
Well, I dont belive in the method of taking off cables of the batter while car is running. This can be dangerous (not always) but can be. Instead I have bench tested all three alternators. One doesnt charge enough, one charges to much, and on is working

The KA one is now installed with minimal fab.

I actually just spent 2 hours searching for the blown ALT/BATTERY 75a fuse in a pick a part for like 2 hours. Finally found one out of a 1995 Nissan Sentra, and installed it. Boom car starts, alternator when connected to battery and car on is at 14.2 - 14.3 which is beautiful and my electronics seem to bee fine.

Test drive soon.

Thanks for the reply!

Tomatosoupp
08-20-2013, 04:18 PM
And I will check out the "Big 3"

soundboy
08-20-2013, 07:04 PM
Awesome

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codyace
08-21-2013, 10:41 PM
Are the doors/locks and the sort still acting funny?

That issue, along with a blown 75amp fuse, leads me to believe either you had a alternator that had failed internally, or a major short someplace. I'd make saure both are not the case before going to far ans having another dead battery.

Skreech_Powerz
11-02-2014, 03:50 PM
I am having this same problem, my car was parked for a month, i come back start it and the batt light came on, i checked all my wires and onnections, started he car after, worked fine, ny wipers went off 3 tines by them self, now my alt is putting out 15v at the alt pole, but my batt is staying at 12.1-12.3v my batt isnt going lower than 12.0v . my alt fuse is srill good, all my grounds and wires are there..

I just started the car today after 3 days of tinkering and again it started charging (i tryed rge remove wire from bat to see if the car dies and it didnt, but the hot wire comming off the alt started to smolder and get hot so i turbed off the car and removed the batt wires incase of short, any ideas??

Uploaded a pic if u look around the boot u might see rhe smoke sorry for the poor quality)


Ok. First thing your alt needs to show 12-14v. The car should cut off if disconnected from the battery. This shows the alt isn't working.

Start the car and make sure that when you disconnect the battery that the alt still shows the 12-14 v.

Also is the alternator charging wire properly connected? Personally I'd upgrade it to either a 0g or 4G wire. Normal car amplifiers wires will work. Google the big 3 upgrade

Sent from my GT-P3110 using Tapatalk 4