ChattanoogaJSB

I read several threads here and on the C3 forum with guys with early cars using the handy search key about ammeter woes. Mine never budges. Earlier I left the car for a week or so on accessory and the stereo ran the battery down to about 4V, so I have the trickle charger on it and my readings at the battery are now right at 12V and rising.

First check: disconnect plug at back of ammeter, check each connection at the connector side (not the gauge side) with my voltmeter to ground. In each case- both connections- with the engine off I get 11.9 volts (basically where the battery voltage is sitting). I also get 11.9 volts at the terminals on the horn relay (side note: my horn isn't working but I understand the buses on the relay "don't care" but I thought I should mention)

I assume without snaking through the headers that my starter side connection is getting the voltage because the plug at the ammeter is. So:

Second check: I get continuity (both tone and a 000 reading) when I switch the tester to check for continuity and cross the two prongs on the ammeter itself. Does this not imply that my windings are good???

Third check: when I turn the headlights on, as is the case when the car is just started, I get no movement in the needle, this has been the case since I bought the car.

I do have a new-to-me gauge set to replace this one with, but I find it surprising I get basically 12V at each plug, continuity in the gauge, and still no drop under load with the engine off.

Can anyone "take me to school" on this?

ChattanoogaJSB

I just had enough extra slack to plug the "new" one in, and it works! The lights do indeed pull a draw on it to the negative side. Well, I know the gauge is bad!

This thread could be open and shut without another reply...except I do wonder how the old one tests for continuity in the winding but won't budge. Maybe it had too many amps through it at some point and fused?

65GGvert

Maybe the winding is good but the movement is stuck.

ChattanoogaJSB

It could be! I'm trying to figure out now when I'll have time to pull the cluster. I have thin hands and I'm even considering if I can figure out how to pull the light switch if I can get to just the gas/ammeter housing to do the job without pull the entire thing out on the bench. I think I can, by dropping the column and gaining a few extra inches and doing it all from underneath. My column is already "cosmetically challenged."

62Jeff

Yes you can do that. Disconnect the oil line too and pull the cluster forward into the interior.

toddalin

The '64 ammeter is very simple to disassemble and replace the windings if necessary. (Been there, done that.) IIRC, there are fewer than 25 turns of the wire on the armature. Just find "magnetic wire" of the same gauge and count the number of turns as you remove them.

ChattanoogaJSB

Should I plan to lose much oil?

Thanks Jeff!

62Jeff

Plan for a drip, don't have your car running!

ChattanoogaJSB

Thanks Todd! I was able to buy a set of either gently used or mediocre NOS small gauges from a forum member a while back, and the new one works when I plug it in temp hanging under the dash...however knowing I can wind one again is a good thing, too! My thanks again.

ChattanoogaJSB

I could not find in my aim how to remove the light switch- except the front pull and trim. I also tried the search without much help. Lb fun link says " tool or screwdriver". Any tips?

62Jeff

Pull the ****, press a button under the switch assembly and remove the **** and shaft. The unscrew the ferrule brought which the **** shaft penetrated, using a big screwdriver or small needle nose pliers.

ChattanoogaJSB

Thanks Jeff for both answers! I'm going to do this tomorrow morning I believe!

nassau66427

I'm guessing your car is a '64. If so:

There's no need to disconnect the oil line or mess with the column or cluster.

Disconnect the battery
Take off the steering wheel to make things easier.
Unscrew the headlight switch and push it back through the cluster.
No need to unhook any wires.
Unscrew the headlight rollover switch and let it hang.
No need to unhook any wires.
Take the connectors off the gas gauge and the batt gauge.
Pull out the 'dash light' in the gas/batt gauge assembly.
Unscrew the 1/4" screws holding the gas/batt gauge assembly in place.
You can now finesse the assembly out.

The entire operation can be done from the comfort of the driver's seat.

Note - the above applies to non AC cars. Don't know what difference AC makes.

ChattanoogaJSB

Except that I was sure I'd want a little excess room, that sounds like the plan- getting those 1/4" screws was all I was unsure how much room is need for (at least the one nearest the door)

Think I'll try it as you say. It looks like there are two screws- right? I was reasoning the one just above the ammeter looks to be a third holding the speedo in, a different plate.

nassau66427

There are 3 screws that need to come out.

For an easier view of what's going on back there, there's a good picture of the back of an instrument cluster here:
http://forums.corvetteforum.com/c1-a...e-cluster.html

Frankie the Fink

All you need to know - straight from JohnZ

62Jeff

Chattanooga, your mileage may vary. I had to disconnect the line in my 65 to gain access. Nassau did not All that matters is what ends up working for YOU. An awareness that an oil line disconnect may be helpful, is probably all my advice is worth at this point.

ChattanoogaJSB

Thanks to all, just wanted to acknowledge I read the last submissions; going to put this off until Monday morning when my son will be in soccer camp and I'll only have the little napper home. I'll write up the result, I feel it's responsible to pay it forward!

ChattanoogaJSB

Just to do the courtesy of closing this thread out for the archives for others to "search" I did replace the amp gauge and the fuel gauge yesterday, I accomplished it by removing the rollover switch, light switch as suggested. Jeff- I didn't have to remove the oil line to move the cluster out enough, but to clear the gas gauge from the Z bar I did remove the cluster screws and the steering column trim panel screws (two) so I could move the cluster forward about 3/4"

The whole job was very easy. Now with my gauge working, I've found my new battery issue, but that's a topic for a whole other post once I have little information (how novel, making a post when I've already done some work!). Basically I have some bubba alternator wiring that seems to have given up and I'm still running an old non-solid state regulator. But anyway, the moral here is the gauge swap is do-able without major dash surgery!