# 1989 Sentra instrument panel warning lights



## e-bum (Jan 23, 2012)

I bought this car a month ago. 1989 with ~129k miles on the odo. I went over a bump today somewhat hard and 3 warning lights turned on:

1. Battery charging light (red)
2. Handbrake light (red)
3. Some light in the shape of the Hi-beam indicator, but on the left side of the steering wheel also turned on (red). Can someone tell me what this light is?

I've noticed that the battery light fades in and out from time to time. The other two are on constantly.

Belt on the alternator still seems tensioned properly, battery terminals are still secured and not loose. 

Took out the multimeter:
Battery with car off: ~12V
Battery with car on: ~14.2V
Alternator with car on: ~14.2V

These numbers couldn't be any more normal, so I'm assuming it's not a dying battery, a faulty alternator or the voltage regulator in the alternator. I could be wrong though. I've only worked on motorcycles, so I don't know if I'm missing something. Does anyone have any ideas? The car is working properly and no changes noticed since these lights have come on.

Help is greatly appreciated... thanks.


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## jdg (Aug 27, 2009)

Could have a bad diode in the rectifier assembly inside the alternator itself. I'm guessing though. I'm not up on the earlier models such as yours.
One way you might be able to check that out is to set your multimeter on "AC" and check how much ripple voltage you have.
With everything off, I'd imagine the ripple voltage shouldn't be much more than 1 volt or so. Anything more could point to a shorted or open (more likely) diode. I say an "open" diode more likely because generally a shorted diode would likely kill the battery just sitting there.

But, I'd be more likely to think that you lost a few connections (i.e. instrument panel plug came loose-ish) or a ground somewhere...which of course will be a PITA to find...


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## smj999smj (Jan 1, 2006)

Charging system testing and inspection:

Turn ignition switch to on position and note charge lamp.
If lamp lights proceed to step 7. If lamp does not light proceed to next step.
Disconnect two wire connectors labeled S and L, then using a jumper wire connect L terminal to a suitable ground.
If charge lamp lights proceed to next step. If lamp does not light the bulb in the instrument cluster is defective. Steps 5 and 6 do not apply to models equipped with Mitsubishi alternators. On these models, if charge lamp lights, the internal regulator or some other internal component is defective and the alternator must be removed for bench testing.
Reconnect two wire connectors, then insert a short stiff length of wire through the access hole at back of alternator until it contacts outer brush. Ground other end of wire to alternator case which will actually ground the F terminal internally, Fig. 3.
If charge lamp remains lit, the internal regulator is defective and will require disassembly of the alternator for repair. If lamp goes out, some other internal component is defective therefore alternator must be removed for bench testing.
With engine idling if charge lamp is lit, a defective internal component exists in the alternator and requires removal for bench testing. If the charge lamp is not lit, proceed to next step.
With engine speed at 1500 RPM and headlights on, if charge lamp is not lit proceed to next step. If lamp is lit dimly, let engine idle and measure voltage across B and L terminals. If voltage is more than .5 volts a defective internal component exists in the alternator and requires removal for bench testing. If voltage is less than .5 volts, alternator if considered to be in satisfactory condition.
With engine at 1500 RPM measure voltage at B terminal, making sure S terminal is properly connected.
If voltage reading is above 15.5 volts, the internal regulator is faulty and requires removal of alternator for replacement. If voltage reading is between 13 and 15 volts proceed to next step.
With engine idling and headlights on, if charge lamp is lit a defective internal component exists in the alternator and requires removal for bench testing. If charge lamp is not lit, alternator is considered to be in satisfactory condition.

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Another good reference that explains the charging system and its circuits is Nissan technical service bulletin #NTB94-011. Your charging system may be charging properly, but if the "third circuit" (as it's sometimes called) has an issue, it will keep the warning lamp illuminated. More often than not, the problem is usually internal of the alternator and requires alternator repair or replacement. As already stated, make a visual inspection and double check all of your harness connections first.


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## dreamteam (Jul 29, 2005)

yeah, it sounds like something got knocked loose. Whether it's a ground or connector remains to be seen. Check the nut on the back of the alternator that holds the positive connector.
There is also a voltage regulator behind the cluster (small 3 pronger, not the alternator type) that could be damaged.


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## smj999smj (Jan 1, 2006)

The "dashboard voltage regulator" wouldn't affect the charging system warning light. It's for the coolant and fuel gauges.


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## dreamteam (Jul 29, 2005)

I just remembered that I had a similar problem.
It turned out to be the main connector on the top of the alternator.
This is the plastic plug that "clips" in with a bridled connector. On mine, the bridle broke and the connector slipped out.


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## e-bum (Jan 23, 2012)

Thanks a lot for the responses.

Car is still running perfectly, though I have a rough idle (but I've had that for a little while now-- that could be another thread!). Autozone did their fancy little test on the battery and deduced that the battery is bad (which is no surprise) at the crank (drops below 9V, though still holding a steady charge otherwise). So I'll replace the battery and go from there. I'm fairly certain this is not the issue, however, for the following reason:

The warning lights are not coming on until I turn my steering wheel to the right, at which point the brake light and 'tail light out' light come on. The charging light also goes bright, but then fades away as soon as I straighten out the steering wheel. I'll take a look at the harnesses behind the instrument cluster when I have time to see if I have an odd connection. I'll post again when I figure something out.

By the way, as far as the rough idle goes, I'm certain this car hasn't had TLC in a long while. Would cleaning/replacing the EGR valve be a good place to start for this fluctuating idling? What are the other hot items to check out first?

Thanks again.


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## jdg (Aug 27, 2009)

e-bum said:


> Autozone did their fancy little test on the battery and deduced that the battery is bad (which is no surprise) at the crank (drops below 9V, though still holding a steady charge otherwise).


I wouldn't believe that for an instant...but anything is possible.



> The warning lights are not coming on until I turn my steering wheel to the right, at which point the brake light and 'tail light out' light come on.


Because the rpms drop a bit due to the extra load on the power steering pump.



> The charging light also goes bright, but then fades away as soon as I straighten out the steering wheel.


Because the rpms come back up a bit due to the load on the power steering pump going away.


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