1936 ammeter polarity

[rlcokc]

Am presently installing my wiring harness which came with car. Rhode Island made it in 1983-stored in box and still in good condition. In installing I am stumped as to which post on ammeter is positive and which is ground. Instructions with harness as well as wiring diagrams show the right is positive but the gauge does not have right or left as when installed one post in vertically above the other.  The question is one on top or bottom negative/ground. The positive has three wires which connect to it whereas the negative has one. Anyone know which is which--I assume I am missing something and should be way to tell. Thanks

Rod

[Guest]

There is no "ground" on an ammeter.  All an ammeter does is measure the flow of electrons one way or the opposite.  If you hook your wires up wrong all that happens is that charge reads discharge.  Reverse the connections and all is well.

[Ben Bruce aka First Born]

49 minutes ago, Tinindian said:

There is no "ground" on an ammeter.  All an ammeter does is measure the flow of electrons one way or the opposite.  If you hook your wires up wrong all that happens is that charge reads discharge.  Reverse the connections and all is well.

 

 What he said. I would bet the post on the ammeter is the starter side. The wire from the generator/voltage regulator probably goes to the side with one wire attached.

 

  Ben

[packick]

Rod:

 

I checked my notes from when I installed a new harness in my '36 Special.  I got my harness from Y&Z and in their instructions every time they said PS (passenger side) of the instrument, that meant TOP if the terminals were vertical.  For instance, there is a yellow wire with one red slash and one black slash that goes from the light switch to the PS (read "top") of the ammeter to the BAT on the cut out relay.

 

Hope this helps.

[pont35cpe]

Rod, I have a instrument cluster I purchased a while back that has the original wiring harness attached. Amp gauge, 3 wires on the top post, 1 wire on the bottom post.

[DonMicheletti]

The one wire post goes to the battery

[rlcokc]

Appreciate the responses and Tom the most help may be the old gauge cluster you have.  Joe didn't think your post would help until I went back and looked at the instructions where they said left and right and assume that is their instruction on Pass or Driver side and using the suggestions from your experience I assume that would mean PS-passenger would be top. My whole purpose is to get this right and not have to crawl under the dash more than necessary as my age and physique does not lend itself to the gyrations necessary to mess with the dash.  Actually I believe all of the responses were helpful and accurate.

After reviewing the wiring diagram it appears that the 3 wires would/should go on the top post. In an effort to solicit the wisdom of those much more schooled in the electrics of the car I have tried to determine exactly which wires go on the posts as I believe I didn't correctly wire my other 36 Buick which started this issue as I did have three wires on the top post but changed them yesterday because I when the car ran the ammeter read backwards i.e. it showed discharge when running as opposed to the car charging. Now I believe I may have had wire from generator on a post by itself and the wire from the starter with the other two.

After reviewing the wiring diagrams as well as instructions with the harness I have determined how I think the wiring should be. The single wire in my case would come from the starter solenoid  where it is connected to the same terminal as the positive battery cable. This would connect to the  bottom post of the ammeter.The three wires consist of the cigar lighter, ignition switch. light switch  and the radio in my vehicle(with suppressor) and come from the the generator cutout relay "battery" and connect to the top post. 

On the wiring diagram there are (+) and (-) signs-for instance: "From generator relay "Bat" to ammeter right(+)".  For the ammeter left (-) the wire comes from a splice in starter solenoid "Batt" to horn relay. This is obviously a positive battery connection so not sure of the signs meaning unless the left (-) is supposed to be telling me it is the lower of the two posts on the ammeter. 

Sorry to be so dense but the wiring not my strong suit and still trying to figure out if I have a strong suit.

By the way the field lead on my generator not connected to anything, normally attached to generator case, I assume all i need to do is ground it, is that correct?

Really appreciate the help.

Rod

[packick]

Rod:

 

I am 6'1" and I agree, crawling under the dash is not for old people like me.  What I did is remove the front seat cushion and made a platform out of 1/2" plywood to set on the seat frame.  That gave me much more room to lie down and work under the dash.  I bet a lounge cushion over that plywood would help too.

 

Good luck and Happy Holidays.

 

Joe

Edited December 23, 2017 by packick
Typo (see edit history)

[mcdarrunt]

I usually check an amp gauge wiring with a battery and a pair of jumpers BEFORE I crawl under a dash. With one jumper hooked to one gauge terminal and to one battery post I then hook the second jumper to the gauge and do a quick arc to the other side of the battery. This arc represents a draw (like say head lights) so the needle should jump to the discharge side. If it goes to the charge side then it needs to be wired in the opposite way. Eighty one in three weeks so need all the help I can get for folding into tight quarters.