Speedometer Calibrator/ Electric to Electric



The Electronic Ratio Adapter (ERA)


Any change in a vehicle’s tire size or rear axle ratio will cause the speedometer reading to be inaccurate.
The (ERA) is designed to correct this problem.
With the ERA, you simply hook up four wires, set the DIP switches according to the calibration table included with your order, and you are ready to go.
The ERA receives the current speedometer signal from the speed sensor and will output the correct speedometer signal to your speedometer.
The ERA four-step wiring is a snap. The ERA is compatible with most cars and trucks.


• Resettable dip switches for
   future tire size/rear gear
• Easy to follow calibration
• Wide pulse range

What does the Electronic Ratio Adapter do?

The automotive industry has a great variety of part sizes, types, shapes, and descriptions, but regardless of make, model or year, a few things are standard. One of those standards has been the number of revolutions a speedometer cable will make for each mile traveled. Nowadays, electronic pulses have replaced the rotating cable, but the same principle applies. The Pulse Ratio (the number of pulses per mile traveled) remains the same, regardless of speed, since the same distance is traveled and the same number of pulses have occurred each mile no matter what the speed was during that mile.

However, this Pulse Ratio can be made to vary from the truth when modifications are made which change the number of electronic pulses per mile on a particular vehicle. This is most commonly caused by changing the tire size (increasing the outside diameter of the tires will cause the tire to travel further before making a complete revolution), but other modifications could have the same result. When the Pulse Ratio is thrown off, the speedometer/odometer will be inaccurate and corrections must be made.

This relative difference between true speed and the speed indicated on the speedometer is called the Variance Ratio, and it is corrected using the AbbottElectronic Ratio Adapter.

Wiring Diagram of Abbott Electronic Ratio Adapter:

Ratio Adapter
(Red Wire) + 12 volts, ignition on
(Black Wire) Ground
(White Wire) Signal in from the speed sensor
(Blue Wire) Signal out to the ECM


Additional information

Weight 12 oz
Dimensions 5 × 5 × 2 in


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