In order to use most aftermarket Plug and Play ECU’s on your 2017 Grom, you’ll need to do a harness mod.
Don’t worry, you won’t have to splice or cut any wires. All you have to do is change the pin-out.
Tools You’ll Need:
- Small pair of needle nose pliers
- Very small metal pick
- Very Small metal flat head screwdriver (eyeglass repair kit style)
Let’s get started!
First, disconnect your battery and remove the panels (clutch side) needed to get to the ECU. Locate the ECU and unplug it. Pull the harness towards you exposing the wires for easy access.
Step 1) Unclip the wire side of the connector by gently prying up on the 4 retaining tabs. Pull the plastic piece upward straightening the wires out as you go.
Step 2) Use the pick and pull up on the orange rubber gasket. Work your way up the wires to gain more exposure. Remove the small red dummy plugs filling the empty holes on the wire side of the connector.
Step 3) Unclip the ECU side of the connector end and remove the cover revealing more holes. There are 9 clips.
Step 4) Re-pin the harness. The connector consists of 3 rows and 11 wires in each. Below is guide that will tell you the location of the pins and wires.
- Pin 1 is Blue/Black. End of row 1 is Pin 11 which is Purple/Blue
- Pin 12 is Blue/Yellow. End of row 2 is Pin 22 which is Yellow/Black
- Pin 23 is White/Yellow. End of row 3 is Pin 33 which is Yellow/Green
Pins to Remove and Replace
- Remove pin 28 (Yellow/Orange) and insert it into pin 20 (empty slot).
- Remove pin 33 (Yellow/Green) and insert it into pin 28. Leave pin 33 empty.
- Remove pin 22 (Yellow/Black) and insert it into pin 19.
- Remove pin 18 (White/Blue) and insert it into pin 22. Leave pin 18 empty.
Tip: To remove the wire, place the pick into the larger hole and gently prying upwards towards the smaller hole. Gently pull the wire with the needle nose pliers at the same time slipping it out of the connector. If done correctly, the wire should come out with very little effort. Slide the wire through the rubber gasket and the plastic holder. Do this by sliding it back through the plastic wire holder and rubber gasket in the corresponding hole. Insert the pin with the flatter side opening facing the big hole. Using the very small flathead screwdriver, carefully push on the metal crimp portion down into the connector. The pin should be seated all the way down, locking it into the connector. Make sure it can’t be pulled out. The pin will only lock in one orientation.
Step 5) Reassemble the harness by sliding the orange gasket and black wire holder back down into the connector and clip it back into place. Insert the red plastic dummy pins back into the empty slots of the connector on the wire side. Clip the ECU cover back into place making sure all 9 tabs are properly seated.
From here on you can follow any other ECU installation guide to complete your setup!
Special thanks to Chris Hammack for being brave and creating this guide for us!