1965 Ammeter Question

[Andy K.]

My original ammeter has been tested and is operational, but somewhere in the wiring there is a problem preventing the ammeter from working when connected. Until I can restore the entire dash, is there a way of bypassing the wiring to enable the ammeter to function? Thanks.

[Jim T.]

Re: 1965 Ammeter Question

I once had a similiar problem on my 1970 that was fixed with replacing a fusable link coming from the alternators wiring. My alternator quit working and a rebuilt replacement was installed. Upon starting the 70 the ammeter pegged to full charge immediately with the rebuilt alternator causing the small wire in the fusable link to burn and saving the wiring. The rebuilt alternator was replaced as well as the fusable link and the ammeter guage was good.

[Terry D.]

Re: 1965 Ammeter Question

Andy
You don't mention if the alternator has been tested. Do you have a wiring diagram for your car? If so it should be easy to follow the wires back and see if there is a break somewhere.
Terry

[Wayne W.]

Re: 1965 Ammeter Question

Unplug and clean up the bulkhead connector. Probably will fix the problem.

[Tim S.]

Re: 1965 Ammeter Question

Unplug and clean up the bulkhead connector. Probably will fix the problem.

ditto!

[Andy K.]

Re: 1965 Ammeter Question

ditto!

Thanks for the suggestions guys. I did clean up the bulkhead connector and the ammeter does work. I am afraid to take the wiring apart for fear of opening a Pandora's Box, before I get around to replacing the the wiring harness. I was just looking for a quick fix.

[William C.]

Re: 1965 Ammeter Question

Andy the wiring is an integral part of the operation of the ammeter. If you do a search in the archives there are numerous in-depth discussions on this. The "ammeter" in a '65 is really a very sensitive voltmeter that measures voltage drop across a wire from the voltage regulator the the fuseblock. That is why cleanliness of the connection at the bulkhead is so important. I assume that is the issue you are describing when you say the gauge "works" but does not operate in the car as intended.

[Andy K.]

Re: 1965 Ammeter Question

Bill, the ammeter was tested separated from the wiring and is functional. The problem arises when the wires are connected to the back of the ammeter, then there is no function. I don't have any electrical problems. The battery stays fully charged. The ammeter just does not work.

[William C.]

Re: 1965 Ammeter Question

That is the exact description of a high resistance connection at the firewall. The meter actually measures the voltage drop across a sensing wire that measures voltage drop across the ends of the main power feed and imputes current flow (direction and magnitude) from that voltage drop. Clean the connection at the firewall, or just learn to live without the ammeter function.

[Andy K.]

Re: 1965 Ammeter Question

Thanks, Bill. I give it another cleaning.

[William C.]

Re: 1965 Ammeter Question

You really need to check all the connections in the circuit, there is a two way connection at the back of the ammeter, and the system actually measures the voltage drop between the horn relay main power feed and the battery cable connection at the starter soleniod, so as you can see, it is a very small volatage change between those two points that is used to calculate current flow both directionally and volume wise (amps). A poor connection at any of those points will give an inop amperage reading as the voltage differential that is being measured between the sensing points is less than 1/4 volt.

[Andy K.]

Re: 1965 Ammeter Question

You really need to check all the connections in the circuit, there is a two way connection at the back of the ammeter, and the system actually measures the voltage drop between the horn relay main power feed and the battery cable connection at the starter soleniod, so as you can see, it is a very small volatage change between those two points that is used to calculate current flow both directionally and volume wise (amps). A poor connection at any of those points will give an inop amperage reading as the voltage differential that is being measured between the sensing points is less than 1/4 volt.

Taking your advice Bill, I aggressively cleaned the fuse box connectors on the engine side of the firewall and the plug going to the ammeter. The ammeter is alive, but it registers on the negative side of center when I turn off, then turn on the ignition. Is there a way to adjust the needle? The system is definitely charging. Thanks for your advice.

[William C.]

Re: 1965 Ammeter Question

If it is not a zero when all power is off, I don't know of a method to recenter the pointer. The real question is does it show a positive charge right after the engine starts?

[Joe C.]

Re: 1965 Ammeter Question

Taking your advice Bill, I aggressively cleaned the fuse box connectors on the engine side of the firewall and the plug going to the ammeter. The ammeter is alive, but it registers on the negative side of center when I turn off, then turn on the ignition. Is there a way to adjust the needle? The system is definitely charging. Thanks for your advice.

The needle should be centered with the ignition switch off and the interior lights off (doors closed). If you want to check it, remove the neg battery cable. If the needle swings to zero after you do this, then you have a current draw somewhere. If your clock is the original style movement (not quartz), then you will get an intermittent current draw when the solenoid rewinds the mainspring.

It is very unlikely that the needle has moved on its shaft.

If you want to bypass your existing wiring temporarily, as a test, then reference this link:

http://img.photobucket.com/albums/v216/speedo1952/Scan10001-1.jpg

[Andy K.]

Re: 1965 Ammeter Question

No, it does not show a positive charge when the engine is running. The needle is in about a 11 o'clock position when the ignition is off. When I turn on the ignition the needle goes farther to the left, thing returns to the 11 o'clock position when the car is running. However, before I got the gauge to move at all, it was stuck in a negative position. I do not have a drain on the battery.