I have a 1986 Nissan D21 4x4 with the KA24E.
I am currently having some problems with her.I just replaced the battery the other day, and have been having some problems with her dieing on me.
If i have it running and turn on the headlights, the lights will start to get real dim and the truck will want to shut off.If i turn the headlights off, she starts running fine again.
So i started her up and did a few quick tests.While running and no accessories I am right around 14 where i should be
As soon as I turn on the headlights it starts dropping at a pretty rapid pace.
Where can I start to check? Any ideas?
Insane battery draw from headlights while running - help!
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C-Kwik
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Re: Insane battery draw from headlights while running - help! (S13xCrazy)
My initial thought is that you might have a short somewhere. Given it seems to be in the headlight circuit, I'd start testing there. I'd first isolate which lights it affects. Try turning on just the parking lights. Then the low beams. Then the high beams. If only the parking lights cause the dimming, then start there (I hope this isn't it as there are more parking lights than headlights).
If its either the low beam or high beam, I'd try unplugging the bulbs individually and testing the low and high again to rule the bulbs out. If the problem exists with the bulbs unplugged, I'd look to the +12 volt leads for the beam that is causing the problem. It should be an easy test. With the bulbs unplugged and the headlights in the off position, test for resistance to ground on the +12V terminal for the affected beam. If there is anything but infinite resistance, then there is a short.
If this isn't the problem, then further testing would be required. A wiring diagram of the entire circuit would also be very helpful.
What perplexes me a bit is that if there is a current draw that is large enough to cause such a large voltage drop, I'd have expected the fuses to blow. Could be a bad alternator perhaps.
If its either the low beam or high beam, I'd try unplugging the bulbs individually and testing the low and high again to rule the bulbs out. If the problem exists with the bulbs unplugged, I'd look to the +12 volt leads for the beam that is causing the problem. It should be an easy test. With the bulbs unplugged and the headlights in the off position, test for resistance to ground on the +12V terminal for the affected beam. If there is anything but infinite resistance, then there is a short.
If this isn't the problem, then further testing would be required. A wiring diagram of the entire circuit would also be very helpful.
What perplexes me a bit is that if there is a current draw that is large enough to cause such a large voltage drop, I'd have expected the fuses to blow. Could be a bad alternator perhaps.
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nismopu
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Re: Insane battery draw from headlights while running - help! (C-Kwik)
load test your new battery. I think its bad. Take it to a parts store and see if they can or put a voltmeter on it and watch the volts while cranking. peace.
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Q45tech
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Re: Insane battery draw from headlights while running - help! (nismopu)
People don't realize that an alternator has 3 seperate windings in parallel. A diode failure in one circuit can drop capacity by 33% and 2 diodes blown can drop capacity by 67%.......................have the alternator ripple current measured, along with peak capacity BY an expert with test equipment, who is not a minimum or even $12 hour idiot.