ammeter issue/question
Thread Starter
Pro
Joined: Apr 2006
Posts: 647
Likes: 22
From: Norwalk CT and Boynton Beach FL
ammeter issue/question
I have a stock 1975 convertible, L82
The other day while on the highway I noticed the Ammeter bouncing around wildly, then getting pinned to the +40 reading. I pulled over and with the engine idleing, the gauge was at neutral (zero), but as soon as the RPM's were above idle, the ammeter got pinned to +40.
Well, I needed to drive the car, so after a few minutes driving, the ammeter needle just read neutral (zero) and didn't move at all. I assumed the voltage regulator in the alternator went bad, so I bought another alternator and installed it, but the ammeter now still just reads neutral (zero) at all RPM's. I assume the NEW alternator is good, but I will check the alternator out tomorrow just in case I got a lemon from Ecklers.
Before I buy another ammeter and take the dash apart, what else could I check? Were are the fusable links for this circuit and where is all the wiring that is not under the dash that I should check? Any help or ideas of what to check before I start pulling the dash apart will be greatly appreciated.
Thanks
The other day while on the highway I noticed the Ammeter bouncing around wildly, then getting pinned to the +40 reading. I pulled over and with the engine idleing, the gauge was at neutral (zero), but as soon as the RPM's were above idle, the ammeter got pinned to +40.
Well, I needed to drive the car, so after a few minutes driving, the ammeter needle just read neutral (zero) and didn't move at all. I assumed the voltage regulator in the alternator went bad, so I bought another alternator and installed it, but the ammeter now still just reads neutral (zero) at all RPM's. I assume the NEW alternator is good, but I will check the alternator out tomorrow just in case I got a lemon from Ecklers.
Before I buy another ammeter and take the dash apart, what else could I check? Were are the fusable links for this circuit and where is all the wiring that is not under the dash that I should check? Any help or ideas of what to check before I start pulling the dash apart will be greatly appreciated.
Thanks
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
I'd check the battery terminals for corrosion and the ground wire that bolts to the frame below the battery box. Does the ammeter show a discharge when the headlights are turned on? There are two fusible links, one by the horn relay and the other by the wiper motor. Check for continuity between those to test the meter. BTY, any local parts store can get an alternator for you.
Race Director
Joined: May 2006
Posts: 18,736
Likes: 2,582
the other failure point is the two wire connector on the alternator. Unplug the connector with the engine running, you should get a reading of over 12 volts on the larger wire, the smaller wire will have a much lower voltage.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
It is very common for the small single-strand wire at the side plugin to break inside the connector and then the alternator quits charging off and on. You can buy a replacement plugin with 8" leads from any auto parts store for about $5.
Thread Starter
Pro
Joined: Apr 2006
Posts: 647
Likes: 22
From: Norwalk CT and Boynton Beach FL
I'd check the battery terminals for corrosion and the ground wire that bolts to the frame below the battery box. Does the ammeter show a discharge when the headlights are turned on? There are two fusible links, one by the horn relay and the other by the wiper motor. Check for continuity between those to test the meter. BTY, any local parts store can get an alternator for you.
Thread Starter
Pro
Joined: Apr 2006
Posts: 647
Likes: 22
From: Norwalk CT and Boynton Beach FL
Cleaned up and tightened up all connections on the alternator, then connected the battery and started the car up. Using the multimeter, it was clear the alternator WAS DEFINATELY CHARGING the battery, but the ammeter was not moving even if I turned the headlights on and put the brights on. I decided to drive the car home--- ammeter read dead ZERO all the way home. When I pulled into my garage, I turned the lights on and saw the ammeter move a little negative and then move to the center. Did this several times and ammeter jumped a little to the left and then immediately back to neutral. Maybe the gauge is working after all --- just that the battery has a good charge on it since I've had a battery charger on the battery 24/7 while the car was sitting waiting for the delivery of the alternator.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
You amp meter may have died.
Here is a marked up schematic I did some years back.
Maybe it will help. About the only way to know is pull the meter, you should have 12v on both sides of the meter. Check the meter itself for continuity with your ohm meter
Here is a marked up schematic I did some years back.
Maybe it will help. About the only way to know is pull the meter, you should have 12v on both sides of the meter. Check the meter itself for continuity with your ohm meter
Drifting
Joined: Mar 2014
Posts: 1,744
Likes: 278
From: Akron OH
I have to agree with SIXFOOTER. A winding in your ammeter may have fried. I had this issue about a year ago and was able to repair the ammeter by carefully removing the face and soldering the fried area back together. Good luck.
Rick
Rick
Last edited by AkrHack; Jul 23, 2015 at 10:03 PM.
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Former Vendor
Joined: Aug 2006
Posts: 76,656
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I'm impressed that you took the gauge apart like that. In the old days when gauges were not available we would take them apart and just re-wind them. The wire is available at most hobby shops.
For us as a shop the labor cost way exceeds the price of a new gauge but for an individual to re-wind one it's not.
Willcox
For us as a shop the labor cost way exceeds the price of a new gauge but for an individual to re-wind one it's not.
Willcox
Team Owner
Joined: Jul 2008
Posts: 23,419
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
I was driving my car today for the second time after getting pretty deep into some electrical problems (that you folks helped me with a TON!). I looked down, and my battery gauge was pinned on the discharge side. I headed back to the garage thinking I was having a big problem, and shut off the car. The gauge is still pinned on discharge. I disconnected the battery, and the gauge is still pinned to the discharge side. Did I manage to fry my gauge?
If we think so, is there an easy way to test it without removing it?
If we think so, is there an easy way to test it without removing it?
Le Mans Master
Joined: Jan 2001
Posts: 6,742
Likes: 1,384
I suggest checking your battery terminal voltage
....before starting to tear anything apart.
If, at idle, your battery terminal voltage is good then you may have an open fusible link(or intermittently open since the car moves and vibrates) which will make the ammeter react oddly, but yet still be charging (depending on which fusible link may have failed).
Below is where the fusible links were located on my 68. Yours may be otherwise located but this will give you an idea.
https://www.corvetteforum.com/forums...locations.html
If, at idle, your battery terminal voltage is good then you may have an open fusible link(or intermittently open since the car moves and vibrates) which will make the ammeter react oddly, but yet still be charging (depending on which fusible link may have failed).
Below is where the fusible links were located on my 68. Yours may be otherwise located but this will give you an idea.
https://www.corvetteforum.com/forums...locations.html
Last edited by carriljc; Nov 14, 2015 at 12:51 PM.
Instructor
Joined: Sep 2015
Posts: 216
Likes: 16
From: Haverfordwest Pembrokeshire
My ammeter doesn't ever move but the battery is charging at about 14volts, from reading the above it looks like it could be a failed fusible link, I've checked one by the horn relay and that's intact, is there only one in that location? and where is the other one on Sixfooters drawing?
Thanks
Graham
Thanks
Graham
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
I was driving my car today for the second time after getting pretty deep into some electrical problems (that you folks helped me with a TON!). I looked down, and my battery gauge was pinned on the discharge side. I headed back to the garage thinking I was having a big problem, and shut off the car. The gauge is still pinned on discharge. I disconnected the battery, and the gauge is still pinned to the discharge side. Did I manage to fry my gauge?
If we think so, is there an easy way to test it without removing it?
If we think so, is there an easy way to test it without removing it?
Well we dont know if u have an ammeter or a voltmeter. A look at your profile shows u dont have a profile for your car let alone u. So try to correct something we dont really know what it is on what it is and where it is on the planet is difficult. U say discharge so i assume an ammeter. If it fails to move from the pegged discharge side of meter w/batt disconnected and no possible current flow then yes your ammeter would be broken.
Team Owner
Joined: Jul 2008
Posts: 23,419
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
So try to correct something we dont really know what it is on what it is and where it is on the planet is difficult. U say discharge so i assume an ammeter. If it fails to move from the pegged discharge side of meter w/batt disconnected and no possible current flow then yes your ammeter would be broken.
Last edited by Derrick Reynolds; Nov 15, 2015 at 09:06 AM.
Team Owner
Joined: Jul 2006
Posts: 22,188
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From: Kannapolis NC
This is what happens when the original thread starter is highjacked by others with "similar" problems and the questions and answers get all mixed up. That's why the forum rules say start new threads with your own questions instead of tacking on to someone else's. It makes it much easier to troubleshoot one set of symptoms at a time. I think there are at least three different cars involved in this thread.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
OK PK the problem was probably on my end then. Im having problems with Chrome loading. Cant see much on Craigs List either. I couldnt resist saying something as thats the typical troll image (nothing) - but u do have a generous post count.
As 65GG mentions a lot of old threads that get revived are only "high jacks" by trolls. I do sometimes see old threads reopened because of very related issues and i have to say there are exceptions to everything. Hey thats why we have jury trials isint it? But more an exception as many or even none of the original participants can respond and they become a great waste of time for those trying to help.
As 65GG mentions a lot of old threads that get revived are only "high jacks" by trolls. I do sometimes see old threads reopened because of very related issues and i have to say there are exceptions to everything. Hey thats why we have jury trials isint it? But more an exception as many or even none of the original participants can respond and they become a great waste of time for those trying to help.
Team Owner
Joined: Jul 2008
Posts: 23,419
Likes: 22
From: In limbo
St. Jude Donor '13-'15, '17 thru '22
OK PK the problem was probably on my end then. Im having problems with Chrome loading. Cant see much on Craigs List either. I couldnt resist saying something as thats the typical troll image (nothing) - but u do have a generous post count.
As 65GG mentions a lot of old threads that get revived are only "high jacks" by trolls. I do sometimes see old threads reopened because of very related issues and i have to say there are exceptions to everything. Hey thats why we have jury trials isint it? But more an exception as many or even none of the original participants can respond and they become a great waste of time for those trying to help.
As 65GG mentions a lot of old threads that get revived are only "high jacks" by trolls. I do sometimes see old threads reopened because of very related issues and i have to say there are exceptions to everything. Hey thats why we have jury trials isint it? But more an exception as many or even none of the original participants can respond and they become a great waste of time for those trying to help.
I ordered a new ammeter yesterday, so hopefully the situation will be resolved this coming weekend. Thanks for the help!
Team Owner
Joined: Jul 2006
Posts: 22,188
Likes: 4,178
From: Kannapolis NC
While I agree with pretty much everything you said here, I have also been criticized for starting a new thread when there was an ongoing one that was on nearly the exact same topic. Hard to win I guess.
I ordered a new ammeter yesterday, so hopefully the situation will be resolved this coming weekend. Thanks for the help!
I ordered a new ammeter yesterday, so hopefully the situation will be resolved this coming weekend. Thanks for the help!