Blinking Headlights in 1996 Nissan Altima GXE

Hi Sateesh

I've never seen that before.

Are you sure _all_ lights (head lights, turn lights, brake lights, plate lights, etc) go out? Perhaps make sure because there are some fuses and feeds common to some lamps but not to all, as far as I can see on the schematic.

When it happens again, perhaps press down on all fuses and fuseable links in the fuse box under the hood to see if it the problem changes. Maybe you just have a bad contact in that area.

Hope you find it soon. Remco

I did check all the fuses. They seem to be fine. Also last week, I got my battery replaced and I was told by Sears that alternator is fine. I thought it would go away with battery replacement as the old battery voltage was 10.55V on load. Unfortunately the problem still exists.

BTW.. I am sure that it is happening with headlights (in both positions), dash board lights, overhead lamp (inside the car). They do not go out completely but the effect is as if the voltage passing to them is up and down.

Could not check turn lights and stop lights.

Sateesh

remcow wrote:

changes.

Hi Sateesh

Ok, the lights dimming is definitely a clue. Initially you mentioned they 'blink', suggesting they actually turn off. Dimming means that either the path to the lights has a higher resistance than normal or that something draws a lot more current than normal.

I'd check the power connections to the battery first - make sure that the wires are secured at both ends. Take the wires off the terminal and clean them with some sand paper. Also check all ground wires to the chassis and engine - I suspect one is not making good contact.

With the car running and everything on, measure the voltage on the battery. Under full load, it should be about 14V if the battery is charged. If you see any less, clean the wire from the alternator on both sides.

Hope you get it solved soon. Remco

Hi Remco,

Thanks for your inputs.

I have got the battery replaced 3 days back by Sears Auto Center. The wires are secured and they are fine. After replacement, on load the voltage is 15V. So I guess that is also ruled out. Only thing that is left over is, checking the grounding. How do I check that?

BTW.. I didn't understand what do you mean by saying "Dimming means that either the path to the lights has a higher resistance than normal".

If some path has higher resistance, then the volatage on the end is continuously lower than the normal (or stable). It will not have dimming effect. But, in my case, it becomes bright and then normal (it was hard to find out whether dimming effect is, normal to bright to normal or normal to dim to normal). Does it mean it is some kind of variable resistance?

Reards, Sateesh

snipped-for-privacy@yahoo.com wrote:

Hi Sateesh

Resistance is a property all wires have -- the thicker the wire, the less resistance.

Not knowing how much you know about electricity, compare wires to water pipe and voltage to water pressure. If you try to push a lot of water through a thin pipe, it will not all want to all go through it very quickly. This means low flow, high water resistance and high potential pressure. In other words: low electrical current, high resistance, high voltage across the wire. Conversely, if the pipe is very wide, a lot of water can go through it. High flow, low water resistance, and low potential pressure. In other words: high current, low resistance, low voltage potential across the wire.

What can happen is that a path to those lights is going through the equivalent of a thin pipe -- a wire that migh not make good contact. This wire has a high resistance and thus only allows some current to flow to the lamps. Since your lamps require a lot more current than can be supplied through those wires, they dim.

The way to check that is to put a volt meter across your battery while the car is running and all your lights are on. You'll see a voltage of around 14V. You move the positive lead to the fuse box but keep the negative lead on the battery. You should still see around 14V -- if you don't, the wire that is in place between the fuse box and the battery has most likely a high resistance and should be cleaned. If you do see

14V, you move the negative lead to the chassis and check for 14V. If you don't see 14V, the negative lead between the battery and the chassis has high resistance and should be cleaned. You basically "walk" these probes towards the offending light and should be able to determine what path has a high resistance. It can be time consuming and you basically need to have a decent understanding of where your wires are going.

Another way is to just clean all contacts (battery, chassis, engine). Make sure to tighten them all down properly after cleaning.

Electrical problems can be a pain to find. Most of the time it is a bad contact on a ground lead because they tend to be exposed to the elements. Hope this helps.

Remco

Hey Sateesh.

Just one more bit: right -- the wire may not really have a variable resistance. You'd see arcs all over the place. I'd certainly hope not :)

The problem is that multiple devices find their way to ground across a wire that might just be meant for one device. After reading your comment a little more, I see you do understand electricity so the current through this wire is more than normal. The more current through a wire, the more voltage across that wire so less voltage gets to your intended device.

Ohms law is E=IR. (voltage = current * resistance)

For instance, let's say your lamp draws 5 Amps. One leg's resistance (let's say ground) is .5 ohms - let's assume there isn't any resistance in the other leg (doesn't happen, but will make the calculation a lot easier to understand)

The voltage across that wire will be 5(current) * 0.5(resistance) = 2.5 V. So the voltage that your lamp gets at best is 14V(running voltage) -

2.5V(voltage drop on wire) = 11.5V.

Now let's say that for whatever reason (maybe a bad ground) the radio also finds its ground through this path. Assume it draws 4Amps. Total current through this wire is now 5 + 4 = 9 Amps. The resistance hasn't changed but the voltage across that wire has changed : 9 * 0.5 = 4.5V

-- so the voltage to your device changes too: 14V - 4.5 V = 9.5V. Perhaps the device that finds this ground is not a radio, but something that intermittently uses power (maybe a cooling fan) -- you see the point: the lamp will dim when the fan goes on.

I explained electricity in terms of water flow in my previous post because I wasn't sure what you understood when it came to electicity. Please understand I did not mean to patronize you, just make the information understandable. Hope this helps -- "good hunting" finding the problem. Remco

Hi Remco,

I could not trace the problem. Now I have more reasons to believe that the problem is somewhere else.. Since two days, the fluctuation worsened (if you remember from my previous posts, headlights dim according to the tachometer flucutation. Now the tachometer fluctuates between 0 and 1000 rpm and soemtimes car engine stops completely.. Have to wait for 5 minutes to start the engine and wait for the tachometer to stabilize (by keepking leg on gas for couple of minutes) and then move the car.. I guess it is time now to take the car to a mechanic. :-)

Any clue what could be the problem..

Regards, Sateesh

snipped-for-privacy@yahoo.com wrote:

resistance

hasn't

something

Hi Sateesh

Sorry to hear that you didn't find it yet. This almost seems like a different problem because originally didn't just your headlight dim once on a while?

The light dimming / engine dropping in RPM could mean several things. It could be that the RPM is dropping due to the voltage on the battery dropping more than normal. Of course, the voltage across the battery also could drop because the engine RPM drops -- one could be the effect of the other and vice versa. (another adaptation of what came first: the chicken or the egg :) To isolate the actual cause could be tricky.

I'd make sure that your alternator maintains a decent voltage (should be around 14V or so) across the battery's terminals when running at constant speed first -- you may need to put your foot on the accelerator to maintain a certain speed.

Regards, Remco

Hi Remco,

Finally I had to leave the car at mechanic after it completely dead. Yesterday I was told by service center that, distributor has lot of oil leaked into and is a typical problem in 1996 Nissan Altimas. He charged me $450 for the replacement (a remanufactured one with 1 year or 12000 miles warranty on it). Surprisingly after the replacement, the dimming seems to have gone. I went on a test drive for about 25 miles on a freeway, inernal roads etc to make sure that, no more dimming. But this morning when I took my car out, problem resurfaced.. I guess I am now seriously thinking to sell this car.. :-(

Regards, Satessh

remco wrote:

fluctuates

tachometer

mechanic.

Hi Sateesh

Ouch!! Sorry to hear that there were expenses involved - that distributor was a separate problem, then. Oil dropping on the distributor - that must have happened as the oil was checked or added? A little weird that the whole distributor had to be replaced but I guess that could happen.

Maybe when it worked fine when you first got it back is due to a bad contact that may have been jiggled when he was working on it. Those can be a real pain to find. If the dimming is faily consistent, you could try to do the same by observing what happens to the lights when you jiggle wires around. I still suspect a bad ground/power connection someplace. Ground connections foul up easier because they tend to uncovered unprotected connections to bare metal, which has inherent problems (metal oxidizes, disimilar metal reaction, bolts not torqued down properly, etc).

Are you near CT? If so, I could look over your shoulder, if you'd like. Regards, Remco