Instrument Cluster Voltage Regulator

Opened the fuel gauge up on the 65 a body. Disabled the internal instrument voltage limiter (IR) by removing the bimetallic beam on the right. The bi-metallic beam on the left is the fuel gauge mechanism, which uses the third lug (lower left when viewed from the front) for a signal from the fuel tank sending unit, (S on the back of the gauge).

RT-Eng article indicates just bending right bi-metallic beam (set of points) out of the way so they never contact again. Was going to solder something up but knew how that would end. Several nice articles on this.

Ordered one off of e-bay per Bill's link above. I think these are similar to the RT-Eng. unit :sign3:which would have been similar to the E-body rally IR with a ground lug as part of the IR case.

Specified the three ring connectors to the vendor so hopefully can mount with nuts to the outside two lugs: 5.1 volt instrument voltage (upper central lug) and 12 volt ("I" lug on back of gauge), I.e. lower right lug when viewed from the opened front (gauge face removed by drilling out two small rivets).

The external IR will bridge (replace) the former right set of points and old bi-metallic beam on the right with a solid state integrated circuit (IC). The lower right lug (I) will be at 12 volts and the upper (central) lug will be at 5 volts. The central lug will feed 5 volts to the temperature gauge and if equipped to the pressure gauge (later rally dash). The early a body will do this with the printed circuit board (PCB) trace and the later models may use actual male / female terminals. Several models may have the external IR which unplugs and a new IC can be plugged back into the back of the instrument panel PCB.

http://rt-eng.com/rte/index.php/RTE_Limiter_Faq