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View Full Version : T56 -> Autometer Platinum Speedo Hookup



Alphamacaroon
12-21-2020, 12:36 AM
Had a chance to try to calibrate my speedo today and just now realizing that it doesn't work at all. Going back through the manual I realized that the instructions are pretty light in this area so I sort of had to guess...

The T56 has a two wire speedo sensor included with it— so I skipped the part of the instructions where they have you install the speedo sender that comes with the kit. I plugged in the wiring harness SPEEDO SIGNAL and SPEEDO SIGNAL RETURN to the connector— can't remember which one I connected to which on the sender unit, but figured it probably wouldn't matter since it probably acts like a switch. I think hall-effect sensors normally require 3 wires right?

Looking at the wiring instructions for the Autometer Platinum Gauge, it looks like a two-wire sensor should be connected from GND, through the speedo sensor, to the gauge SIGNAL input. Looking through the Ron Francis wiring diagram it looks like one end of the speedo leg ends effectively ends in an open circuit— I assumed one was connected to GND, but it appears like they leave them open ended, maybe to give you the option of connecting it to the VSS input on an ECU?

Anyway, I guess my questions are:

1. Can someone confirm/deny that a RF harness -> T56 -> Autometer Platinum gauge setup requires more than just "connect the two wires as-is"? If it does work out of the box, then maybe my problem is somewhere else.
2. If the answer to #1 is that it doesn't work out of the box, do you have a basic wiring diagram? My guess is that I'll need to connect the wire that isn't connected to the SIGNAL input of the gauge to GND, but maybe someone can confirm or deny that?

Any help would be greatly appreciated!

edwardb
12-21-2020, 06:31 AM
Don't have experience with the Autometer brand specifically. But did a couple Speedhuts before they went to GPS. They required a signal wire and a ground wire. It was common for guys to say they didn't work (agree the instructions are a little sketchy) and when grounded they worked. Maybe yours is the same? Also FWIW, that isn't a hall effect sensor. It's a variable reluctance (VR) sensor. Basically a magnetic core and coil. Not active and doesn't need voltage. So only two wires required.

Erik W. Treves
12-21-2020, 08:42 AM
Signal from gauge to sensor - and the sensor to ground.. I assume you calibrated it correct?

Alphamacaroon
12-21-2020, 11:08 AM
Okay great! Seems to be what I expected— needs to be grounded. I’ll give that a shot.

Erik— I actually tried to calibrate it and that’s when I realized it wasn’t working. It wasn’t counting any pulses.

Much appreciated!

Erik W. Treves
12-21-2020, 01:29 PM
cool.. hope it works out!

Alphamacaroon
12-21-2020, 07:22 PM
Boom! That was it. Connected the gray wire to ground and we're all good to go now. Calibrated and reading true. Thanks again everyone!