What did I do to my ammeter?

[Alpine 1789]

My ammeter has always worked fine, but the light only occasionally worked. I knew the problem was a bad ground, so last night I removed the guage, cleaned the light housing and the bulb holder, lightly crimped the housing so it gripped tighter and re-installed it. Now the light works perfectly but the guage is totally dead. The only thing I can think of that I could have done wrong was get the wires mixed up, but wouldn't that make it work backwards? It is completely dead; doesn't move a bit.

Before I take it out and start over, I thought I'd see if anyone had any thoughts as to what I may have done.

Thanks,

 

[64beam]

Hi Jim,

Reversing the ammeter as you pointed out would make the meter move in the opposite direction and the dash lights should not effect the gauges. Firstly, I would check your connectors around that area that may have been disturbed when you removed it. It does not take much to dislodge those lucas connectors. You could also pull out the bulb holder to see if it had any effect as well.

Good luck, Robin.

 

[burgy711]

I would look inside the engine compartment and make sure you have good connections off the starter solenoid and the regulator. You might have something loose there.

 

[Alpine 1789]

Thanks guys. I am out of town for the rest of the week, but will take a look at it this weekend and report back.

 

[Alpine 1789]

I've been out of town, so today was the first chance I have had since posting this to take another look at the ammeter. Everything looked fine, so I decided that it was time to take it apart and have a look inside. I think I found the cause of the problem: stupidity. I had used coarse steel wool to clean the rust off the bulb housing and there were several stands around the piviot point of the needle. I carefully removed them with a tweezer, cleaned everything and reassembled it, but it is still dead.

At this point, I suspect one of two things is wrong. One is the the steel wool strands shorted something out and I've buggered it. While that is possible, I didn't see any signs of arcing or melted wire to confirm this. The other is that all of my screwing around has the needle pinched and is keeping it from working. Its a very fragile arrangement and putting the face back in without disturbing it seems impossible. So, at this point, I have two questions:

First, is there a trick to getting it back together? Its a correct Lucas 30/30 one, so I'd sure like to get it back working.

Second, I'd like to bypass it until I get it working again. Do I just connect the two wires together and wrap lots of tape around the connection?

As always, thanks.

 

[Nickodell]

Jim, you could just join the two conductors together (if they have ring terminals, join them with a nut and bolt), but I would not for two reasons:

1) The conductors (cables) carry more current than any others in the car, with the exception of the primary one from the battery, and the one to the starter, and is not fused. Wrapping tape around the bare metal is not accepted electrical practice to insulate them, and if they should short against a ground you would have a fine bonfire;

2) There is no need. You can't do any harm just leaving them connected to the ammeter.

The most likely possibilities why the needle is stuck are: either the mechanism is frozen for some reason or you're fouling the needle with the gauge glass. The former is unlikely as, unlike Bourdon tube gauges like the oil pressure one, there are no pinion and sector gears to get gummed up. I had the needle problem with my speedometer when I removed the bezel and glass to clean it. I had to hunt around several foreign car stores until I could locate a new O-ring gasket the right diameter to fit the gauge and raise the glass that crucial extra 1/32 inch to clear the needle.

 

[Alpine 1789]

Thanks, Nick. I think the needle is the problem, too. But I don't think it is the glass. I think it is the faceplate on the guage. The needle has to fit through a small opening and it seems virtually impossible to replace the plate without affecting the needle. I was hoping that someone would know a trick, but suspect it will be trial and error...followed by a new guage.

 

[Jeff Scoville]

Jim, if the gauge is not working that is one thing, if it is not conducting electricity just leaving it hooked up rather than bypassed will result in a soon to be dead battery.

 

[Alpine 1789]

Any way to tell the difference? While Nick cautions against bypassing it due to the current it holds, that is precisely the reason I am thinking of bypassing it. All that current flowing through a broken guage makes me nervous.

 

[odl21]

maybe you should switch to a voltmeter. perhaps we should start a debate on that...

 

[Tom H]

Jeff, a non conducting "anything" cannot discharge a battery.

Jim, Please clarify the situation. I think I understand your situation in that 1) the ammeter does not show any current, as though the needle was stuck but 2) all the needed current is apparently flowing through the ammeter, as evidenced by the fact that all the electrics work.

Is this the case? if so you do not need to do anything extra, except connect the two terminals together IF you remove the meter. But while the meter is installed, even if not indicating properly, if all the electrics work the meter is already effectively "bypassed" internally. I would not worry about the non working gauge in the circuit. There is a low resistance shunt in the meter and if the electrics are working, then clearly that shunt is OK. It is the more delicate meter that is wired in parallel with the shunt (inside the case) that is defective and there is nothing it can do to make things worse.

Tom H

 

[Jeff Scoville]

Tom, that is exactly why i asked if the ammeter was still conducting electricity.
If it is not registering that is one thing, but if it has broken the circuit there will be no charge to the battery as the wire that connects to the ammeter is THE wire connecting charging supply to the battery.
So, to make things easy and without worry, bypassing will keep everything working properly.
Jim, connecting the two wires is simple and safe (common sense with protection from shorting) electricl tape is just fine (that's why it's called electrical tape) obviously more than once around.
This will WITHOUT A DOUBT keep you running and give you time to sort out the meter without keeping the car down.

 

[Tom H]

Jeff,

Ahah, I see your point. BUT, if it is installed correctly (i.e.as per the factory wiring diagram) and it is not conducting, then it would not allow any current to or from the battery. But if it were wired incorrectly, as some have done, where it only monitors current from the alternator, in that case an open ammeter would lead to a dead battery.

Tom H

 

[Alpine 1789]

The Ammeter doesn't budge from center, but everything else works fine. I am not 100% certain it is wired correctly; the car has had an ammeter as long as I've owned it (30 years) and it seems to work, so I assume it is (or was) ok.

I really think the problem is just the needle and realized this morning I have an easy way to find out: I'll remove the face plate and see if it works without it. It that does the trick, I just need to figure out how to put it back on without binding the needle. If not, its time to punt.

 

[Nickodell]

Jeff: I couldn't disagree more, and IMHO what you are suggesting is dengerous and non-professional. You can get away, if you're so inclined, with Mickey Mouse stuff on low-current fused circuits, and you may get away with an unfused cable capable of conducting 50 amps or more flapping about under the dash with a bit of tape on it the same way that you may get away with driving without seat belts or a fire extinguisher.

Sound electrical practice, whether you're dealing with 240v mains AC or 12v DC, mandates that high-risk conductors be attached to fixed terminals. Electrical tape is fine to cover the bits of exposed terminal left (although I use heat-shrink tube myself).

An ammeter is just part of the main electrical feed circuit, with a sensor to one side that detects current flow but is not in series with it. If the needle doesn't move it is no longer detecting anything, but the current flows OK nontheless and doesn't know it isn't being metered, so leaving the cables attached is OK. Let's pretend the needle is a spectator at a motor race. He videotapes the cars going by until his camcorder goes on the fritz. The cars continue, unchanged. Nobody says "oh now we have to divert them to avoid the grandstand because Joe's camcorder doesn't work anymore."

If I sound dogmatic, so be it. I've lost too many friends and acquaintances, and seen too much material loss and grief through accidents so that I won't be diplomatic when I think someone is dead wrong.

 

[odl21]

If I sound dogmatic, so be it. I've lost too many...

can't help but snigger... this coming from the guy who thinks an apline is safer than a [whatever that yaris looking hybrid thing was in your crash thread was] ...

 

[RootesRich]

Since we're on the subject of broken ammeters, does anyone know a shop that rebuilds them?

 

[Jeff Scoville]

An ammeter is just part of the main electrical feed circuit, with a sensor to one side that detects current flow but is not in series with it. If the needle doesn't move it is no longer detecting anything, but the current flows OK nontheless and doesn't know it isn't being metered, so leaving the cables attached is OK. .

Nick, if this is the case then I agree to leave it alone.
That's why I suggested seeing if it still conducted first.
My opinion as to disconnecting the ammeter in WHATEVER manner is SAFE still stands.
A temporary fix can still be accomplished safely without going overboard.
I have seen you get on your "high horse" before and chuckled, but if you read others posts COMPLETELY you would have less to argue about.
In fact, I am trying not to make this an arguement.
We both have an opinion as to getting it done, but if as you say, the ammeter will conduct regaurdless of it's functioning, it's a mute point.
Drive on Jim, drive on.

 

[Nickodell]

can't help but snigger... this coming from the guy who thinks an apline is safer than a [whatever that yaris looking hybrid thing was in your crash thread was] ...

Glad you got a snigger out of it ........ only one problem. I never said any such thing. Either about an Alpine, or even an apline.

 

[Alpine 1789]

This has been a very slow motion repair (busy at work ) but I thought I'd close the loop on this and add a little for anyone who ever finds himself in a similar situation.

The ammeter itself turned out to be fine. I removed the face plate and it worked, meaning that the needle was getting pinched by the plate. So, here's a little advice: don't remove the face plate if you can! Once off, it seems impossible to put it back without bending the needle. I tried several times without success, so I switched to plan B, which was bending the needle back in place with the face plate on. It was hard to find something stiff enough and thin enough to do the trick, but fortunately I was sucking on a Tootsie Roll Pop while I was working. I flattened the end of the stick in a vice and it was the perfect size to force down into the face plate and bend the needle back to where it should be. The needle is very fragile so you have to be careful, but after a few tries I had it back in place and have a working ammeter again.

Thanks to all who gave me advice. On to the next project.