Ammeter question

[Allergydoc]

I have a 57. Installed a new wiring harness which has a red (color) hot wire to one side of ammeter and generic ground to the other. This creates a direct short; ammeter is pegged (>30) and ground wire gets hot in a hurry and blows a fuse. I do not know how the original was wired. The schematic seems to say this is correct. Any help would be greatly appreciated. :confused

 

[Silver Blue 58]

Doc,
While I do not have a schematic for your car ( you might acquire one for your year) I do know that you should not be connecting one side to ground.
Traditionally an ammeter hookup should run between the battery side of the alternator or in this case generator and link into the circuit between the ignition switch and the battery. I believe in some cases a resistor is used in conjunction with hooking into the ignition switch to battery.

This is a general description of ammeter usage, without your wiring schematic it will be hard to determine the placement of your specific wiring harness.

Did you purchase the harness from a vendor? If so they should have supplied an electrical schematic with the new wiring. Otherwise try to get an assembly manual or an ST-12 service manual for your car. One of these should be able to identify your cars ammeter hookup. Maybe someone more familiar with your year will chime in to help.


Fred

 

[Allergydoc]

Doc,
While I do not have a schematic for your car ( you might acquire one for your year) I do know that you should not be connecting one side to ground.
Traditionally an ammeter hookup should run between the battery side of the alternator or in this case generator and link into the circuit between the ignition switch and the battery. I believe in some cases a resistor is used in conjunction with hooking into the ignition switch to battery.

This is a general description of ammeter usage, without your wiring schematic it will be hard to determine the placement of your specific wiring harness.

Did you purchase the harness from a vendor? If so they should have supplied an electrical schematic with the new wiring. Otherwise try to get an assembly manual or an ST-12 service manual for your car. One of these should be able to identify your cars ammeter hookup. Maybe someone more familiar with your year will chime in to help.


Fred

Thanks for the response. I have a schematic provided by the vendor and it is a blow up of the one in the original shop manual. Both being very hard to read due to low resolution. It appears that the ground may go to a terminal in the headlight switch but there does not appear to be a corresponding wire in the harness to to do this. Thanks again for the input.

 

[JohnZ]

There is NO GROUND wire to the ammeter - the ammeter is in series with the main power feed from the starter solenoid (14-ga. black wire) and the load feeds on the other side (14-ga. black to the ignition switch); both terminals on the ammeter are "hot" all the time.

There should be two black ground wires with ring terminals on them in the instrument panel harness, as shown in the Assembly Manual in section 12, sheet 12.00, at the lower right part of the illustration; one goes under a hood release attaching bolt, and the other one attaches to the metal part of the headlight switch.

Suggest you add an 18-ga. fusible link wire where that black main power feed wire connects at the battery cable stud on the starter solenoid - that feed circuit was unfused until 1967, and a dead short will fry that harness from the starter to the ignition switch.

You should also get a better wiring diagram - Don Olson (vetsvette2002@yahoo.com) has laminated color diagrams that are outstanding.

 

[Allergydoc]

This is great information. Thank you so much. -Larry