Technical Information K20 Transmissions

Introduction

With regard to the speed sensor there are two types of transmission sold with the K-Series.

Low frequency type transmission

  • Found in the 02-04 RSX and 02-05 Civic Si.
  • Signal from the speed sensor is at a low frequency.
  • Speed sensor is at the rear of the transmission, run from the final drive at a low frequency.
  • The signal from the speed sensor goes both to the ECU and to the gauge cluster.

High frequency type transmission

  • Found in the 05-06 RSX, TSX and 06-07 Civic Si.
  • Signal from the speed sensor is at a high frequency.
  • Speed sensor is at the front of the transmission, from the teeth on 3rd gear.
  • The signal from the speed sensor goes only to the ECU. The ECU sends a low frequency signal to the gauge cluster.

Matching Components

The following components need to be matched in order for the ECU and gauges to work correctly:

  • The transmission output speed signal frequency (low or high).
  • The engine and dash wiring (low frequency design splits the speed signal between the dash and ECU, high frequency design goes from the transmission to the ECU and from the ECU to the dash).
  • The ECU internal conversion of transmission pulses to speed (in KManager the low frequency type is the default, the high frequency type can be used if the 'Countershaft Driven Speed Sensor' option is selected).
  • The ECU output of speed pulses to the dash (not present with the low frequency type, necessary with the high frequency type).

If all these components are not matched, then either your ECU speed or your dash speedometer will not work (or both will not work).  Repeat: all these components need to be either the low frequency design, or the high frequency design.

How does K-Pro work on the 05-06 RSX?

  • The speed sensor is the high frequency type.
  • The engine and dash wiring is the high frequency type.
  • In KPro you set the speed signal conversion to high frequency ('Countershaft Driven Speed Sensor').
  • Hondata modifies the 02-04 ECU to provide a low frequency speed output to the dash.

From the last point you can see why an ECU prepared for a 05-06 RSX is different from one prepared for a 02-04 RSX.

How can I get an 05-06 transmission to work in an 02-04?

Everything has to be either low frequency or high frequency. You can either make the transmission into a low frequency type, or the vehicle into a high frequency type.

Converting a high frequency transmission to a low frequency transmission:

  • Either drill and tap the rear speed sensor location to accept the 02-04 speed sensor, or swap transmissions cases.
  • Add the speed sensor drive ring to the final drive.

Converting a low frequency vehicle to a high frequency vehicle:

  • Swap to a 05-06 engine harness.
  • Swap to a 05-06 dash harness.
  • Get the KPro changed to 05-06 specifications, with the adapter harness and speed sensor output.
  • In KPro you set the speed signal conversion to high frequency ('Countershaft Driven Speed Sensor').

Altering the transmission to a low frequency type is by far the easiest option.  However, given the choices you will be best off to sell the 05-06 Transmission and get an 02-04 that will work perfectly from the start.