Electrical question

[Christopher]

My 1975 280z coupe has an electrical gremlin. A couple of years ago, while driving in wet weather, the power to the accessories (lights, radio, heater) suddenly dropped severely. After a while, normal power came back. This happened on several other occasions and I took the car to a local Nissan dealer. The technicians poked and prodded and finally gave the car back to me, mumbling something about "loose electrical connections" and such. The electrical system worked reliably until last week, when it pulled that old stunt again. I had let the car sit for a week or two, and on the second day back into the drive-to-work routine, the lights dimmed and the heater slowed way down. I made it to the parkling lot and had it towed to the other local Nissan dealer. After keeping the car for a week, they now tell me it needs a new starter and a new alternator (and please pay us $1,000). I can believe that the alternator might be shot (the ammeter needle on the dash cluster never moves very far to the right, even after a large current draw), but I'm skeptical about the starter. The starter might be less than perfect, but I don't think it's the problem or so far gone it needs replacement. Any thoughts for a new poster?

Chris

 

[DGM]

I agree with you, don't see your starter as the problem and as its an intermittent fault then its doubtful that your alternator is to blame either, but your alternator belt maybe slipping.

 

[Russ]

Well I'm no expert, someone will be along who is but...

What has the starter to do with your car when you're driving? Maybe it does something? But far as I was aware it is just sat their doing nothing. If your car starts alright then what can be wrong with it?

Does the engine still run fine and it's just the electrical side of things that go a bit haywire, or does it go down on power or splutter? Do you lose a cylinder at all or is it all fine?

Just sounds like water getting in somewhere it shouldn't to me. I don't know suspect problems on the 280.

 

[Mr.G]

I also can't see how the starter could be connected.

This may not have anything to do with the rain either, it could be that your charging system cannot cope with the extra load requiring it to power the wipers, radio, heater and lights. This may be why it occurs when it rains as having the wipers on is too much for your charging system to handle.

Does the battery light flicker when the symptons you describe occur?

I think that the symptons you describe could point to your charging system and its best to check this first since it is so easy to do so.

For starters Check the battery - If your battery is not the maintenance free variety then you need to check the level of distilled water in it and top up if necessary. Also check that the battery posts and clamps are clean and making good contact, use a small wire brush or some emery paper if needed, check that the connections onto the clamps are on tight and dont move around - tighten if required.

The next test will require a voltmeter. Start the engine and connect the voltmeter leads directly to the battery (black to negative, red to positive). The meter should read between 13-15Volts, when you rev the engine up to 1500revs the voltage should increase slightly.

Leave the engine at idle and turn on lights, radio, wipers and heaters - if the reading falls below 12.5V then your alternator probably needs changing.

Also you should check the condition of your fan belt - make sure it is not slipping or too loose - if it is you need to tighten it.

 

[Christopher]

Thanks to DGM, Russ and MrG240Z.

The problem doesn't seem to affect how the engine is running. And it comes on suddenly (and when it ceases, it also does so suddenly), so that makes me discount the possibility of a slipping belt.

The ammeter needle moves into the discharge area when the problem occurs, but not by much.

The voltmeter test sounds like a promising approach.

I'm tempted to tell the Nissan dealer to order the alternator and forget the starter. The alternator replacement looks like it's a straightforward in-and-out job. Is that right?

Chris

 

[Mr.G]

yes it is very easy - you could do it too.

 

[Christopher]

Thanks, George.

 

[Tony 260Z]

Well, starter problems sound far-fetched to me. You could have a starter problem that's unrelated to the engine-running current-supply fault, but I fail to see how that would manifest itself when the engine is running. Likewise with the battery - if that was dodgy I wouldn't expect the car to start - but it's worth checking because batteries can recover charge when not being used (unless totally flat) so maybe it could hold enough charge to start the car but then not be able to hold charge afterwards. I'm not sure about that theory though so I hope an auto-electrical whiz can correct me if I'm wrong! For my money, it's the alternator and it could be something like a broken wire or the voltage regulator on the blink. Even the brushes - they do wear down after all. I can't remember how to test it (sorry!), but you might find that removing it and cleaning all the connections would make a difference.

Good luck!

 

[Bass in me Zed]

it sounds to me that it could be a bad earth from your battery the only real way of testing this properly is doing a drop test with a dummy load meter .. failing that .. when the problem occurs use a heavy gauge jump lead from you battery negative terminal and connect the the other end to your car earth points one at a time and see if that cures it, i used to find nissans suffered with bad earth probs when i used to work in the auto electrical industry
John

 

[grolls]

If you go read my electrical thread (anything and everything) you could work it out for yourself instead of guessing.

 

[ben240z]

If you go read my electrical thread (anything and everything) you could work it out for yourself instead of guessing.
worth the time visiting that forum. guessing is going to end in tears, or fire!!!!!!!!!! grolls has spent the time putting up a very useful diagnostic. and it's free to use