What's the electrical box on back of combo meter

[Digger48]

https://photos.google.com/photo/AF1QipM7FZBzwY2v-o41XXsWRMNeZu-hFWymsqm-q63s

 

Vehicle: 1973 PL 620 -- Can anyone tell me what the small (about 1" cube) electrical box fastened to the back of the speedometer is?  It has 3 wires connecting (green, red & yellow).  The only thing that comes close in the service manual wiring diagram is either the voltage regulator for the temp-fuel meters or something labeled as "amp" with a connection to the "spd sw."   The temperature and fuel gauges are both not working.  Based on the threads I've found on Ratsun (and the info in manuals) the likely culprit is the temp-fuel voltage regulator.  Some of the threads have indicated that the VR is built into the temp gauge.  If that is the case (and my temp gauge does have what Datsun Mike posted as points and a bar with white wire) what's the electrical box?Hopefully my attached picture URL works and you can see what I'm referring to.   One possibility with the "spd sw." might be the old retarded vs. advanced timing points that the original 1973 620s had (which I long ago by-passed).  Anyone know?  Thanks.

Edited April 5, 2019 by Digger48
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[datzenmike]

It's the speed switch and detects below 10 MPH and activates the vacuum control solenoid on your carburetor. I bet your speedometer does not read down to zero but stops at 10 MPH.

[Digger48]

Thanks, Mike.  I presume then that the voltage regulator is the micro-wire wrapped bar and points built into the temp gauge?  I have examined it, see no broken wires or connections, emery-papered the points and hope that gets the gauges back working again.

[abbylind]

IIRC the points are a voltage regulator to make sure the fuel and temp gauge receive a constant steady voltage. I thought mine was bad as both gauges (temp and fuel) didnt work. Cleaned the contacts where the wire connector meets the temp gauge sender and the same on the gas tank. Both had corrosion...both started working....