is "voltimeter" even a word?!?!

Indeed, with today's gas prices and 15-17 mpg, who can afford to pay a mechanic? Or even to drive at all? That's why I parked my Explorer in the garage and re-commissioned the long mothballed 21 year old LTD. No ABS, no airbags, no dual-media entertainment system, and the headlights don't turn on and off on their own; but boy, that obsolete throttle body injected V6 and three speed transmission are still happily delivering an astounding 19 mpg!

Don't know much about Lucas oil products. Electrical products by the same name have a spotty reputation, but I have not heard of any of those ever being used in an Explorer... So before we pull out the chart, let's figure out if this is just the gauge, or the voltage is actually flickering. The simplest way to tell might be parking at night in front of a wall, taking your foot off the accelerator and observing the headlights. If the lights are bright and steady, you can probably leave your vehicle parked right there and go to sleep peacefully, as there is little to worry about (unless you are a perfectionist like me, and want every gauge to work in a 15 year old vehicle with over 200,000 miles). The other crucial piece of information that you kept secret from us is whether the engine is idling steadily or not. If it idles poorly, the voltage will be justified in doing what it's doing and you need to take care of the idling.

And no, it does not rhyme with 'altimeter'. The word is 'voltmeter'.

It seems to flicker like a stereo equalizer

It's "voltmeter".

This reminds me of a maddening problem I had with a Ranger which was much like this. I traced an intermittant short thru the wiring harness to the cigarette lighter/ashtray. I don't smoke, so I throw change in there. I had left the lighter out of the socket when plugging something else in, and a penny had slid down into the lighter socket- It didn't make good contact, so it didn't blow the fuse or smoke, but the vibration at idle would cause it to jiggle and intermittantly short. It did make the voltmeter needle thrash around. So it could be something like that- anything that intermittantly draws a lot of current. You could pull fuses a few at a time to see if you can isolate it to a particular circuit. Suppose you pull the dome light fuse and the problem goes away. Look for a pinched wire or other similar problem in that part of the wiring.

More info would help- does it crank strong? Does the battery hold a charge if it sits for several days? Do your brake lights work correctly?

-Paul

My first inclination would be to wiggle test the harness/connectors involved in the charging system while an assistant watched the lamp (engine running, of course). Spread connectors, corrosion, previous repairs or modifications.... these are just some of the possible causes.

I have found no crankcase oil additives (and few other additives) worth the expense. Nothing beats timely maintenance and repairing small concerns before they grow into budget busters.

As for additives.... I'm reminded of a quote I once heard.... "I you build it, they will come...." (we could follow that up with P.T. Barnums "There's one born every minute..."). As for repair and maintenence, I have my own quote...."Cheap ain't".

testing...

The battery cranks like a home run hero on the cream, stays charged like a hurricane, and the break lights work right. At a steady idle of 900 RPM I can notice obvious flickering in the radio illumination, not to mention the dash lights and the heavy-drawing headlights. I replaced the $150+ alternator (rebuilt) 8 or 9 months ago and have had no prob until now. I will test all fuses-good insight. All connections were tested and deemed tight and right by an amateur wrench. I was under the impression a voltmeter was a type of testing equipment, not a gauge. My first vehicle, a four-door Wimbledon white '68 Lincoln Continental had a similar gauge labeled ALT, but it never worked after the engine fire. (F.Y.I. The $90 wiring harness was substituted with a $7 trailer wiring harness that worked perfectly, even after four starters.) Note: I have a disintegrating muffler- could air compression be a culprit? Did I mention it is a Ford? Lucas oil additive has silenced the knocking at high speeds for two years. $7 a bottle x six services is $42. I may be a sucker, but at least I can hear my radio. Thank you everyone for dispensing your valuable mech knowledge to unknown proles like me!!! Thanks for all past and future help!

Very nice, traveler!!! I was told LTD stands for "La Tee Da" I suspect is means "Limited" Surely you must know, Shirley? Thanx for the help.

OK, that eliminates your alternator and the battery.

At a steady idle of 900 RPM I

This could be either an intermittant short (not a total short, but a resistive one) such as a pinched wire or a wire rubbing a bit on ground. It could also be a bad ground in the circuits affected, which instead of being a solid connection, is resistive. Like the screw or bolt that is supposed to hold it firmly against the chassis is loose and has some corrosion.

It can be either. It measures voltage, which in a water analogy is like water pressure. An ammeter measures current, which is like water flow. An ohmmeter measures resistance, which is like the nozzle on your hose, where you can vary the restriction to change the amount of flow.

The test instrument has a bunch of ranges so it's general purpose (and it's usually a multimeter, which can measure resistance and current as well as voltage), and quite accurate, the gauge is made to measure something specific and usually is less accurate.

You can get a multimeter at Radio Shack for as little as $15. Voltage is measured between two points, usually ground and something you want to measure, like the battery.

A shop manual probably has a step-by-step troubleshooting procedure for the charging system. But you have a tough problem here. It's a lot easier to troubleshoot something that doesn't work at all than something that has a subtle problem.

I'm an electronic tech by trade, BTW. Troubleshooting is what I do.

-Paul

Thanks for the detailed analysis, Paul. Does TAN compensate you for your time invested in improving their website?! Every car repair and maint I perform, the more often I notice once a small problem is found many others come into play at the same time. A friend of mine lent to me his multimeter and every current and voltage tested was optimal. Looking closer, I noticed a slight whistle where there should be no whistle and found a small piece of tape blocking a triple nipple vacuum port located on the rear of the right side valve cover. A larger hose continues a few inches and connects to the rear right sight of the throttle body. A small nipple(is this the right term?) protrudes forward and is definitely sucking in quite a bit of air. I can see no dangling hoses anywhere. Several eyes have inspected the entire engine compartment-nothing. Is this to some sort of electrical and/or vacuum sensor? The gauge instantly resumed normal operation when I unblocked the port. (Blocked with green electrical tape mostly sucked inside the port-clearly no professional install) The engine is a V-6 4Liter 4X4 with cruise, air, power. Thanks for your help Hunter

You may have a headlight switch going south.

Sounds like you are describing a PCV valve (a part of the crankcase ventillation system). In some applications they may provide a convenient vacuum tap-off for another accessory, but probably not in your case. The vacuum diagram label inside your engine compartment should show that very clearly. Most likely someone just installed a 'universal' PCV valve, with an extra port and did a poor job of capping it. Unmetered air ('vacuum leak') sucked through there may cause unstable idling, explaining your fluctuating voltage. Things might have gotten a lot more 'interesting' if something was flapping around instead of just allowing a steady leak. Did you notice the MIL (check engine light) turning on? The computer should have detected this condition.

There is one unused port on the vacuum distribution block. The tape fix is a hack job. Any auto parts store will have an assortment of caps that will solve that problem correctly.

Charlie

The vacuum tree makes a lot of sense. I was reading the post as something installed in the valve cover, and he probably meant 'to the rear of'. Not familiar with the pushrod V6, but its PCV valve is probably somewhere else, in a much harder to access location. One way or another, unmetered air will wreak havoc on your idle. The ten cents spent on a real vacuum cap are a good investment.

I understand there is an extra port on the vacuum ditribution block and that it should be plugged, but I do not understand why the electronic fluctuations stopped entirely once it was unblocked. I allowed a few minutes of idling so it would relearn the correct idle, as instructed in my owner's manual. The gauge remained perfectly still. My assistant plugged the port and the engine very nearly died and the gauge again went haywire until it was unblocked. My check engine light has illuminated a few times in three years, but always turns off after a few minutes or engine restart. Help!

I would risk a guess that your IAC (Idle Air Control) valve is clogged or otherwise inoperative, and the air supplied through that open port is keeping your engine idling. IAC failure is very common - use Google to search posting on this group. Pulling trouble codes out of the computer might be very helpful to confirm (Autozone and its siblings allegedly do this for free in most states). Oh wait a moment, did you say it was a 92? Autozone probably won't, but all you need to read the codes is a paper clip. This link if for the Bronco, and the location of the test connectors might be slightly different, but otherwise still useful:

There are code readers for 92s. I have one.

Charlie