Is this normal?

HI Steven: Ali allowed me to take her '94 XJS out yesterday, because it needed gas and a wash! The ammeter performed just as yours, a bit of an indication that the load increased, then right back to the normal charging level.

Robert, you might try right clicking on the link and selecting 'save target as'. That will download it to your computer and it should play then.

Good luck!

Hello Steven. I think your description fully answers my original concern - the instrument is not dampened like the older XJS with barrel type gauges. The meter is VERY responsive when loads are applied, and immediately returns to normal, charged position.

I was not able to open your WMV file, but I am reasonably sure that it would show a dynamic response meter.

In summary. For my car, I think the operation is normal.

I'm not trying to be argumentative here, but I happened to have a '95 XJS on my hands yesterday. Here's a short video of the voltmeter as the brake pedal was repeatedly pressed. I think it pretty well matches Robert's description and my contention. These instruments just are not dampened like the older XJS with the barrel type gauges. Those moved like molasses.

Cheers,

You're the ony one using "oscillation", William :-) . The original post doesn't mention or imply it, not by my understanding of the word, at least.

For the heck of it I checked my XJR. As you mentioned it takes a fair load before the needle responds. OTOH, on my brother's Chevy van the needle does indeed respond to brake lights and turn signals.

I dunno, but I think it's more of a meter sensitivity thing than an actual fault. Later I'll do some experimenting with a DVOM and see what happens :-)

Cheers
DD

No it is not, I think there is some confusion here, The term used was oscillation, But just co confirm my understanding I went to the garage (it is absolutely pouring rain here in Los Angeles) and started the 94 XJS. I let the voltmeter slowly settle then, I pushed the brake pedal no reaction, I switched on the headlights, no reaction, I opened the left window, no reaction right window, no reaction, turned on the AC no reaction, with the AC 0n I operated both windows, there WAS a reaction, the voltmeter slowly moved down a little I then revved her up and the needle slowly moved back up. Clearly it takes a very heavy demand to reduce the voltage, more than a turn signal or brake lights, if that is the case there is problem in Roberts car. Interestingly, when we (british cars) switched to Voltmeters from ammeters we , the dealers, got many complaints about low battery readings. We had to explain to customers that when the car first starts it will take a few minutes for the voltmeter to show proper battery voltage as voltage change is slower than current draw, They were used to the ammeter system where one got instant increase/decrease! Darn, if it wasn't for the rain I could have taken the S for a run. Regards

Thank you to Doug, Bill, and Steve. I appreciate your input and your experience.

Like I said, everything works. Just did not know if the responsive voltmeter was telling me something, or just telling me it is sensitive. I have had this car for 2 years,. It starts right up, drives beautifully, and I have enjoyed putting 12,000 miles on it. I just wanted to know if anyone else experienced this visual with the dashboard voltmeter.

I'm afraid I'm in Doug's corner here. Call me weird, but I have for years used the voltmeter deflection Robert describes as a confirmation a load is working. Testing brake lights, turn signals, seat heaters and even power windows. If I get a voltmeter deflection when I press a window switch, I know the switch must be working and the motor stuck. If I get nothing, I start at the switch.

I wouldn't worry about a thing Robert.

My two cents.......

Edited on 2012-04-13 21:06:07

Because voltmeters do not react that fast, an ammeter on my Morris Minor might, but on a modern car there should be no oscillation!

William, why wouldn't it be normal for the voltage reading to momentarily drop when a load is introduced?

The only part that seems abnormal to me is that the volt meter is that sensitive to a minor load. Most (including mine) are not that responsive.

Am I missing somethng in the conversation? Or are you saying that it's the sensitivty of the volt meter that's a problem?

Cheers
DD

NO! it could be a bad connection somewhere. an alternator problem or a gauge issue. Some basic tests of the charging system should nail it down.