YACT: Nissan 300ZX Electrical Problems

[Scarpozzi]

I'm going to make the description of this short and sweet. My friend has a '91 300ZX (non-twin turbo). He tried to start his car Thursday after work to go home and it wouldn't start....the battery was dead. So I went down and asked him if he wanted a jump. He said he'd rather just go get a new battery, so I removed his battery and we replaced it with a brand new one from Advance. He drove home.

The next day, he got up, went to work, and after work, the new battery was dead. He didn't drive far enough for this to be an alternator problem and he didn't leave his lights on. Something is draining the battery and we don't know what. Does anyone have any suggestions?

I took my voltmeter and did a resistance check to make sure the positive terminal on the battery wasn't grounded out somehow, but we didn't see big sparks you'd get from that either when we plugged the battery up. I wanted to check the current, but the amp meter wasn't showing anything stable to start with so I can't check the battery and pull fuses. I wasn't able to find any interior lights on or any systems on in the passenger compartment. I'm looking for any other suggestions. Thanks,

-Scar

 

[radioouman]

I don't think that new batteries come charged, so it sounds to me like the alternator is dead and the new battery was never charged.

I'd recommend charging the new battery with another car. THen put a voltmeter on the new battery. Start the car and see if the voltage goes up... IF the voltage doesn't go up, then the alternator is dead.

 

[flot]

Ask on http://www.twinturbo.net - but this does not sound like a z-specific issue. It just sounds like a general electrical problem. I agree with the 2nd poster, you haven't necessarily established that your friend's alternator is working.

It's hard to imagine that anything would be draining the battery that fast but you wouldn't notice that it was on. Offhand the only Z specific issue I know of is the factory "alarm" occasionally gets screwed up so that the alarm light blinks constantly from the second you take out the key from the ign - (the "alarm" light should NOT blink constantly, it should go off after about 30 seconds after you lock the car) but that usually takes 5+ days to drain your battery.

 

[Gravity]

My battery came charged. I'd be looking at that regulator or alternator. No juice going back to the unit. This, of course, also means that the old battery might not have been bad.

 

[Scarpozzi]

New batteries do come charged. They should be just around 12-13 volts. The issue here is when he put a new battery in his car and drives 6 blocks, parks it for 8 hours, the battery shouldn't be dead. It's not like he left his lights on or the radio on. I checked the voltage in the driveway earlier and it read 3 volts. An hour later, it was at 2.3 volts. Something is eating it....

 

[slag]

its probably something like a glove box light or something that wont turn off.

 

[radioouman]

Originally posted by: Scarpozzi
New batteries do come charged. They should be just around 12-13 volts. The issue here is when he put a new battery in his car and drives 6 blocks, parks it for 8 hours, the battery shouldn't be dead. It's not like he left his lights on or the radio on. I checked the voltage in the driveway earlier and it read 3 volts. An hour later, it was at 2.3 volts. Something is eating it....

That's true... But that would be a major drain.... Good luck

 

[Scarpozzi]

Originally posted by: Gravity
My battery came charged. I'd be looking at that regulator or alternator. No juice going back to the unit. This, of course, also means that the old battery might not have been bad.

I don't believe the second battery was bad. Based on the 5 year norm, it would be somewhere close to the end of its life though... There was corrosion on the old battery so it was good to go ahead and get a new clean one for a quick fix. Unfortunately, it didn't turn out to be the real problem. I sincerely exhausted the chance of a bad alternator since he hasn't been driving the car enough. A battery should hold a charge for at least a day or so without an alternator for a short drive as he has. (6 blocks to work)

 

[Actaeon]

I know Autozone or whatever can do a test on cars to determine if the Alternator is still functioning or not. Not sure where you live, but it was free for me (Orlando, Florida).

 

[Scarpozzi]

Originally posted by: slag
its probably something like a glove box light or something that wont turn off.

My dad had this problem on his Cadillac recently. The courtesy lights wouldn't go off. We looked for the switches and checked them and they all seemed like they were working. (no door ajar light either) So we ended up having to take the bulbs out.

Unfortunately, I couldn't find a light that was on, but I'm going to keep looking for something. I guess the best thing for him to do is maybe send his car to a dealership and get them to check the computer to make sure there isn't something going on there. (that could definitely drain some battery if it was malfunctioning) Thanks for the guesses. I just want to make sure I cover all the bases before he goes to a mechanic that charges him excessively for no reason.

-Scar

 

[HappyPuppy]

Originally posted by: Actaeon
I know Autozone or whatever can do a test on cars to determine if the Alternator is still functioning or not. Not sure where you live, but it was free for me (Orlando, Florida).

Bingo. They can also determine if there is a drain on your battery while your engine is shut down.

 

[Quixfire]

Scarpozzi, I can tell you how to fix this problem if you have access to a wiring diagram, a voltmeter that can measure amperage draw, and a lot of patience.

Start by determining how much of an amperage draw is across the positive terminal by using a 10-amp fuse. Remove the positive battery cable and put the fuse between the positive battery post and the cable. If the fuse blows, then the draw is over 10 amps. If the fuse doesn't blow then it is safe to connect your voltmeter to check the amount of the draw.

Please let me know what you find.

 

[halik]

i drive a 1990 Z car and never had any problems like that. I would tend to think that the alternator is dead, or something is shorting out somewhere. Measure the current across the terminals

 

Scarpozzi ;

First off, verify that the alternator is charging, hook up a ohm meter to the battery, set it to 20V DC, start vehicle, the meter should see 13.8 to 14.7 V, this will indicate that the alternator and associated wiring is working.

Next, remove the negative battery terminal (make damn sure the ignition is off), attach the red (positive) lead of the ohm meter to the negative cable, attach the black (negative) lead of the ohm meter to the negative battery terminal, set the ohm meter to amps, the reading should be no more than 1/2 amp MAX, if it is, do the following ;

One by one remove the fuses until the drain ceases, this will narrow down on where to look for the drain.
If by chance that none of the fuses stops the drain, either the starter is shorted or one of the diodes in the alternator has burnt and the aletrnator is acting like a motor, thus draining the battery.