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My 78 280z is draining the battery with the key off, I installed a new ignition switch thinking the stock one was worn out as the key just falls out. When the key is switched off the volt gauge reads full battery voltage. Normally the gauge returns to zero when the car is off, any suggestions. Could the voltage regulator cause this?
 

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I'm pretty sure my 1980ZX voltage gauge always shows 12 Amps when the car is off. It's at the shop right now, so I can't confirm, but I don't remember seeing it at 0 when the car is off.

Doing a little searching on Autotrader Classics, looks like my suspicion is correct. Here's an 83 for sale where you can see the car is off (0 on the tach, and no lights on the dash, so key isn't in the On position), and the voltage gauge is not at 0.

106670
 

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My 78 280z is draining the battery with the key off, I installed a new ignition switch thinking the stock one was worn out as the key just falls out. When the key is switched off the volt gauge reads full battery voltage. Normally the gauge returns to zero when the car is off, any suggestions. Could the voltage regulator cause this?
Here's a picture of your circuit. As it shows, your voltage meter is wired directly to the battery and independent ground. So, it should always read your voltage even with the engine off. That's how my 77 works. It's possible that your old ignition switch was shorting the passive feed to the meter and that was why it read zero.
If your battery is draining with the ignition switch off, I'd say either the switch is not wired correctly or something with a direct battery connection is shorting to ground. The voltage regulator would'nt be my first guess but if you haven't replaced it yet with a solid state unit, you should. The old Hitachi, mechanical regulators, are terribly unreliable. The solid state replacements are cheap and easy to install.
 

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Gsorbets, one thing you failed to mention. Did you have a drain on the battery before you installed the new ignition lock? What makes you think that the battery has a drain on it? Is your battery going dead or are you just assuming that it is because the gauge is ready battery voltage? The volt meters are always hot on these cars. If they're not hot with the key off then there is a problem with the gauge or somewhere else in the car. They don't cause a drain on the battery just because they're registering battery voltage. In your original question you referred to the volt gauge returning to zero when the car is off. Then you asked if the voltage REGULATOR could cause this condition. Zacny77 was the only one besides myself that caught the mention of the volt reg. Please straighten all of this out for us so you can get the correct and proper answer to your query.
Zacny77, just so you know, the old Hitachi external voltage regulators were far superior to anything else on the market. I'd rather have a used old Hitachi unit than any of the new solid state units on any of my z's without a doubt. I've never seen a brand new Hitachi unit bad out of the box or go bad in the first few months whereas with solid state units I've seen at least 10% bad out of the box and about another 20% fail within the first few months, or at least cause a sizeable fluctuation in the charge rate or an overcharge which isn't good either. I still have numerous 70-77 z's with the original Hitachi volt reg on them and the charge system is fine. The solid state units are cheap because they're using low quality parts and they're made in China or Honduras or some place like that. How many of the old Hitachi regulators have you had to replace? Just wondering what evidence you're using to base your opinion on. FYI, Gsorbets has a 78 z and they use an internal voltage regulator, not those cheap solid state regulators. If he tried to put one on his z he would have a lot of trouble finding a place to plug it in.
Gsorbets, I assume that you replaced the ignition lock and switch. FYI, I rebuild ignition locks and can recode them back to your original key code if you so desire. Beware of a cheap ignition lock replacement that has come out for these cars. They're easy to spot because they don't use the same size of switch and they don't have any wires for the key minder (buzzer).
Z man of Washington
www.zspecialties.com
www.datsunstore.com
 

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the '78s do not have external voltage regulators - they use the ZX alternator which is internally regulated. Only the '78s are internally regulated, '77s still use the external regulator.
 

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Gsorbets, one thing you failed to mention. Did you have a drain on the battery before you installed the new ignition lock? What makes you think that the battery has a drain on it? Is your battery going dead or are you just assuming that it is because the gauge is ready battery voltage? The volt meters are always hot on these cars. If they're not hot with the key off then there is a problem with the gauge or somewhere else in the car. They don't cause a drain on the battery just because they're registering battery voltage. In your original question you referred to the volt gauge returning to zero when the car is off. Then you asked if the voltage REGULATOR could cause this condition. Zacny77 was the only one besides myself that caught the mention of the volt reg. Please straighten all of this out for us so you can get the correct and proper answer to your query.
Zacny77, just so you know, the old Hitachi external voltage regulators were far superior to anything else on the market. I'd rather have a used old Hitachi unit than any of the new solid state units on any of my z's without a doubt. I've never seen a brand new Hitachi unit bad out of the box or go bad in the first few months whereas with solid state units I've seen at least 10% bad out of the box and about another 20% fail within the first few months, or at least cause a sizeable fluctuation in the charge rate or an overcharge which isn't good either. I still have numerous 70-77 z's with the original Hitachi volt reg on them and the charge system is fine. The solid state units are cheap because they're using low quality parts and they're made in China or Honduras or some place like that. How many of the old Hitachi regulators have you had to replace? Just wondering what evidence you're using to base your opinion on. FYI, Gsorbets has a 78 z and they use an internal voltage regulator, not those cheap solid state regulators. If he tried to put one on his z he would have a lot of trouble finding a place to plug it in.
Gsorbets, I assume that you replaced the ignition lock and switch. FYI, I rebuild ignition locks and can recode them back to your original key code if you so desire. Beware of a cheap ignition lock replacement that has come out for these cars. They're easy to spot because they don't use the same size of switch and they don't have any wires for the key minder (buzzer).
Z man of Washington
www.zspecialties.com
www.datsunstore.com
Thanks Zman, I didn't know the 78's had the internal VR. Good to know. I bought my 77 new from the dealer and when I picked it up, they told me the VR was bad but they ordered a new one and would replace it under warranty the next time I was in. The new one lasted about a year and went again. After that I replaced it myself once or twice. Anyhow, I finally put a solid state unit in that had a nice dichromate case and looked stockish. It's been in over 25 years now and hasn't had an issue. Love your website! Looks like you have a great shop.
 

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Slightly off topic, but ZMan, do you still have your ZSpecialties shop in Washington? And more importantly, your online store? I've checked your Datsun store site a few times over the past couple of years and it always says it's under construction. Just hoping that you're still going strong and wanted to make sure I don't have the wrong website. You've always been the end-all authority on anything Z, and that's a fact. Have a good one!
 
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