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280z clock question


mlaw7

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Since restoring my '78, all of the electronics have worked fine - until today. And I think I know why.

I've been using my cell phone charger in the lighter with no issues for several weeks now. The lighter element worked great too. And I never noticed any change in the voltmeter reading (both the voltmeter and fuel gauge work fine).

This morning, however, I noticed that I wasn't getting any power to the charger. Just to verify, I then tried the lighter element and it too didn't work. I also noticed that the clock, which had been keeping near perfect time, stopped right around the same time this happened.

When I got home from work, I checked the lighter fuse and sure enough, it's blown. I don't have a spare 10v fuse and it was too late to go to the auto parts store but I'm pretty sure the lighter will be fine with a new fuse.

All the other gauges and lights still work fine.

What about the clock though? The cell phone charger evidently not only overloaded the lighter fuse but also blew the fuse or relay for the clock. Here's where I'm stuck.

Can someone please tell me what the circuit protection is for the clock? I haven't seen any fuse or relay associated with it.

Second, why or how would overloading the lighter affect the clock?

Guess I won't be using my cell phone charger in the Z anymore :cry:

Thanks!

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Problem solved!

I found a good 10 amp (not 10v as incorrectly stated in my first post) fuse and replaced the blown lighter fuse with it.

As I thought, the lighter element works fine again. And so does the clock! It's back to keeping near perfect time.

Seeing that my car is practically 100% stock, including the harnesses and other electronic components, I have to conclude that the lighter is on the same circuit as the clock. Does this sound correct? Or is there something strange somewhere in my wiring?

It does makes sense, since they both operate independently of the ignition switch circuit.

But if that is indeed the case, does anyone know why doesn't it say so on the fuse box cover or in the owner's manual? I looked thru the FSM as well and didn't see anything. However, I attribute that more to my rudimentary knowledge of reading electrical diagrams.

Now I'm wondering how many times what seems to be a dead clock is really a similar electrical issue.

Thoughts? Comments?

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That's correct. The clock is on the same circuit as the cig lighter. Other manufacturers refer to that circuit as 'common unswitched' meaning that it's hot regardless of key position. The only place it shows in the FSM is in the Body Electrical section. Page BE-70, illustration BE-125 shows the clock circuit drawing it's power from that 10A fuse, third one down on the right column. If that fusible link in the illustration blows, it will also stop the clock but it would also stop the other five circuits it feeds as well.

post-3797-14150810387418_thumb.jpg

Edited by sblake01
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Thanks man!

So is it odd that using a cell phone charger, or for that matter, any other device such as an electric air pump would create an overload like this? Is this indicative of a problem or weakness in my electrical system? Or is the S30's electrical system simply not designed to handle loads like this?

I'm guessing there were no devices like that back in the 70's. Or were there?

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Check to make sure that your fuse clips are tight. The old glass style fuse clips spread over time, and when you apply a heavy load they arc and overheat. Sometimes, if you are lucky it blows the fuse. If you are unlucky it melts a hole in your fuse block.

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Thanks man!

So is it odd that using a cell phone charger, or for that matter, any other device such as an electric air pump would create an overload like this? Is this indicative of a problem or weakness in my electrical system? Or is the S30's electrical system simply not designed to handle loads like this?

I'm guessing there were no devices like that back in the 70's. Or were there?

The only thing I had like that in the 70s was an electric shaver that plugged into the cigarette lighter socket. It didn't work all that well but I don't reacall ever blowing a fuse while usnig it.
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