Installation Guide

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RatioSync Gear Ratio Correction Module Kit for Sprinter by Agile Offroad

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Installation Manual

The RatioSync Gear Ratio Correction Module Kit is a purpose-built, plug-and-play solution for correcting vehicle behavior after changing the differential gear ratio on a Mercedes-Benz Sprinter.

A single RatioSync CAN filter supports 3.92, 4.18, and 4.36 gear ratios, eliminating the need to select a ratio-specific module when ordering. The module is configurable to match the vehicle’s installed gearing, helping restore proper engine operation, transmission shift logic, and overall drivability.

SKU: S12-1004

TOOLS NEEDED

  • Trim Clip Removal Tool
  • T25 Torx Bit
  • 10mm Socket/Wrench
  • Straight Pick Tool

INSTALLATION TIME: 2-4 Hours

NOTE: It is important to disconnect the vehicle battery when working on any electrical systems.

Installation Steps

1

  1. Module Connector
  2. 12v Key Hot Fuse Terminal (Gray Wire)
  3. 12v Constant Fuse Terminal (Red Wire)
  4. Communication Busbar
  5. Not Used
  6. Yellow/Green Wire Connector
  7. Ground Ring

2

Use a T25 Torx bit to remove the passenger side floor mat edge trim.

3

3. Remove the front footstep floor mat.

4

Remove the tool tray.

5

Remove the mid-dash trim panel.

6

Use a T25 Torx bit and a trim clip removal tool to remove kick panel.

7

Locate the factory communication buss bar with the blue wired connectors. Push up on busbar to remove from mounting panel.

8

The busbar has five unlabeled module communication connectors. One is for the transmission. Determining which connector is coming from the transmission module will require a trial-and-error procedure.

9

Push release tab and remove the first connector.

10

Install the connector removed onto the AO wire harness communication busbar.

11

Locate the two open busbar mounting square holes on the factory busbar mounting panel.

12

Install the AO wire harness communication busbar as shown.

13

Install the Yellow/Green wire connector to the factory communication busbar.

14

Re-install factory busbar to mounting panel.

15

Use a 10mm socket/wrench to install AO wire harness ground ring to the factory ground stud.

16

At the footwell fuse panel, locate the gray and magenta fuse holders.

17

Use the second from bottom open fuse socket for 12v constant.

18

Use the bottom open fuse socket for 12v key hot.

19

Use a T27 Torx bit to remove the lower fuse panel screw.

20

Route the AO wire harness from busbar panel to the footwell fuse panel.

21

Install the AO wire harness 12v constant fuse terminal (red wire) into the magenta open fuse block. Use a straight pick tool to push fuse terminal into fuse block until terminal locks in.

22

Install the AO wire harness 12v key hot fuse terminal (gray wire) into the gray open fuse block. Use a straight pick tool to push fuse terminal into fuse block until terminal locks in.

23

Re-install the fuse panel. Install supplied 3 Amp fuse into the newly wired fuse openings.

24

Use the supplied wire ties to secure the AO wire harness to the factory harness. Route the module connector towards the center cupholder location.

25

Pull up on the cupholder to remove.

26

Continue to route the module connector to the cupholder cavity.

NOTE: The vehicle ignition must be in the off position while going through the programming process. The RatioSync module will illuminate at initial plug in at which point you can start the programming steps below. The ECU will return to sleep mode, and the lights will turn off on the module if no buttons are pushed within approximately 10 seconds of the initial plug in. To re-initiate the programming mode, disconnect and then reconnect module connector.

27

Install the module box to the harness connector.

28

The module will light up as shown when connected.

29

Press the two buttons simultaneously for approximately 5 seconds. The blue light will flash then will stay on when in program mode.

30

Use the right and left buttons to toggle the gear ratio selection. 1 red light is for 3.92, 2 red lights are 4.18, and 3 lights are for 4.72 gears. To complete the RatioSync module programming, close all van doors. Use key fob to lock doors and allow the van to sit for 10 minutes.

31

The following steps must be used to test if RatioSync is connected to the transmission communication module:

Drive the vehicle on road that allows the following procedure to be carried out safely and within the law.

  1. Drive van up to 40-50 mph.
  2. The transmission should shift through all 7 gears.
  3. If transmission only shifts to 4th gear, carefully pull over.
  4. Turn off van. This allows the transmission to shift back 1st gear.
  5. Drive van back to home/shop keeping speeds below 25 mph.
  6. Repeat steps 8-12 but now trying the next communication connector from the busbar.
  7. Drive van following the steps above.
  8. Continue until these procedurers until the transmission shift through all 7 gears.

32

Use the supplied Velcro pad to attach the RatioSync module inside the cupholder cavity. Re-install cupholder, vehicle trim panels and floormats using steps 2-6.