REM Quick Start Guide

REM Quick Start Guide

The Race Expansion Module (REM) is used in conjunction with the Haltech Elite 2500 ECU to offer extra Input and Output functionally as well as advanced traction control and other advanced functions. Using the REM with the Elite 2500 allows sequential staged injection of up to 16 injectors, and will drive up to 32 injectors. This setup will also provide control of direct fire, wasted spark or distributor ignition systems.

The REM also has additional Analogue and Digital inputs which can be used for data acquisition as well as additional Digital outputs.

Input / Output Summary


  • 8 x Fuel Injection Outputs (Peak And Hold (0-8A Peak / 0-2A Hold)
  • 4 x Digital Pulsed Outputs (Low Side Drive 1A Max)
  • 4 x Digital Pulsed Outputs (High or Low Side Drive 1A Max)  


  • 4 x Digital Pulsed Inputs
  • 10 x Analogue Voltage Inputs 

Communications and Communications Wiring

     In order for the Elite 2500 and REM to communicate accurately, consistently and at high speeds we need several communications lines. Theses communications lines include CAN Communicatons, Digital outputs to Digital inputs as well as a power relay control system.

   CAN Communication

     The REM CAN wiring must be connected to the Elite 2500 via the REM ECU connector (Pins B23 and B24).

   Watchdog Communication

     The Watchdog communications are a high speed error checking to ensure that the Elite 2500 and REM units are both online and errorfree. This communication system requires REM IGN1 (A3) to be connected to the Elite 2500 SPI4 (B7). This function is hard set in the ECU and the input and output cannot be re-assigned.

   Solid State Relay (SSR) Communication

     The solid state relay which is used to power all stages of injection is controlled with 2 outputs, one from the REM and one from the Elite 2500. This method ensures that all stages of injection have the same power supply which is important when determining injector current control.

     This communication system requires REM DPO5 (A24) to be connected to pin 2 on the Haltech Conditioning Circuit, while Elite 2500 DPO4 (B19) will be connected to pin 3 on the Haltech Conditioning Circuit.

     This function is hard set in the ECU and the input and output cannot be re-assigned.

   Injector Stage wiring:

     Each stage of injection running off the REM unit requires a synchronization output from the Elite 2500 to be wired to an SPI on the REM unit. This function is hard set in the ECU and the inputs and outputs cannot be re-assigned. Wiring for up to 3 stages of injection controlled via the REM is as follows:

   Stage 2

    Elite 2500 DPO2 (A1) must be connected to REM (B1)

   Stage 3

    Elite 2500 DPO3 (A3) must be connected to REM (B2)

   Stage 4

    Elite 2500 DPO1 (A18) must be connected to REM (B8)

Software Setup

   Enabling the REM

     Connect the REM to the Elite 2500 via CAN then go online with the Elite 2500. All USB communication is performed through the Elite 2500 ECU. Enable the "Race Expansion Module" under Main Setup > Devices > Race Expansion Module. You can also Enable the "Auxiliary Inputs and Outputs" available on the REM unit in this menu. Please note you may use either the REM Auxillary Inputs and Outputs OR Haltech I/O Expander 12 boxes but not both at the same time.

Enabling a set of Staged injectors

     In this example we will be driving 8 primary injectors off the Elite 2500 ECU and 8 secondary injectors off the REM unit on an 8 cylinder engine. Go to Main Setup > Engine > Fuel and change the "Number of Stages" to 2. Configure the Staging Setup for the second set of injectors to use 8 outputs in sequential mode and configured per cylinder. The drop down box allows you to choose what injector driver you would like to use. Select REM to have the REM unit control the secondary injectors.

     The Maximum Stage Duty Cycle is the value of injector duty required in order to enable the next set of injectors (default 80%), Likewise if the injector duty (when under staging conditions) reaches the "Minimum Stage Duty Cycle" the highest running Stage Number will disable.  If the ECU determines that this will cause the previous Stage to exceed the Maximum Stage Duty Cycle the system will not disable the current stage until this condition is met.   Eg. If disabling Stage 2 causes Stage 1 to exceed the Maximum Stage Duty Cycle, the system will prevent this from occurring by holding off from disabling the highest Stage Number until this condition is met.

Configuring injector characteristics

     You will find these settings under the ECU Navigator tree on the left hand side of the display pages, then "Injection System". You will find Injector Firing Angle, Dead time, Flow and Current settings for each stage of injection. Each of these values must be entered before attempting to start the engine.

Viewing the I/O Report 

     By clicking on the "View I/O Report" at the bottom of the "Setup" menu you will find a resource report. This report lets you know what Input and Outputs have been used and which are still available to use.You will notice in this I/O Report that DPO2 (A1) is being used to syncronise the second stage of injection - It is wired into the REM (B1)

 You will also notice that the available I/O on the REM unit is displayed on the left hand side of the page under "Race Expansion Module". Each of these inputs and outputs can be assigned to features under the "Functions" button on the left hand side of the Setup (F4) page