Bike Dies and/or Dash/Light Flash


Unplug the lights. Both rear lights and any aftermarket modded lights (fisher light headlight etc) . Under a very few limited circumstances we have seen this cause the bike to show as dead.

If your Sur-Ron display/lights flash 1-6 times and shuts down and 30 sec later it starts to flash again in a loop then it's possibly the battery BMS that is acting up. Best thing you can do is to leave the ignition and breaker ON and then connect the charger to the battery, if the charger is charging you can use the current flowing into the cells to actually power the light and dashboard (and enough to make the wheel spin slowly unloaded) So while charging if the lights stays ON then it's very likely that BMS is acting up. So go down this post to step #4 and do the controller bypass. If the lights and display works then email Luna Cycle at (best would be to make a video of the issue as the support agents will ask for it)

If you Sur-Ron does not do the 5 flash thing then please continue with the troubleshoot:

First question, do you have the testing cable (click this link) if yes please turn off the breaker and install it between the bike and battery, flip the breaker and tell me how many times the red LED blinks. IF you dont then please continue. If you do have it and does not blink then please continue.

The first step would be isolate the issue.. it can be the battery or the controller or just a loose connection.

1) measure the voltage with a multimeter: flip the ignition OFF ,then the breaker OFF, unplug the battery fully, wait 30sec, and measure from the charge port, you should be reading anything between 45V up to 67.2V depending on the state of charge.


















Next would be to plug the battery back, measure the voltage from the charge port (see attached) and while measuring flip the breaker ON (note the voltage) then turn the ignition "ON" and measure the voltage again. As you can see in my case the voltage went up a little .. that is because the BMS was sleeping and we just woke him up (really). If you turn off the breaker and wait 30 sec or so the voltage should go back down a little.



















While you are at it inspect the breaker screw-on terminal, if they are loose the wire is maybe not making good contact.











2) Next step would be to pull the controller out a little and inspect the the little wires soldered to the main power lug on the controller.

Just click here to know how to do it and what to look for

If one is not soldered properly then you will need to solder it back!

Dont reassemble the bike yet until you test the bike! The next few steps will require you to have the bash guard and controller out.

3) If you havent inspected the connection yet then it's time to do it, dont pull on the wires, just press them in firmly, check if there aren't any wires pulled out of a connector.

Please watch this video:












4) Unplug the DC-DC buck converter from the system and try the bike, you wont get any accessories working but it can help to see if there was an sensor pulling a voltage down, see previous at the 30sec mark to know what to unplug.

5) ONLY DO THIS STEP IF YOU LIGHTS WERE FLASHING AND DIYING : Now it's time to disconnect the controller power from the battery, so make sure the battery is fully unplugged (very important). Then using an Allen wrench remove the bolts securing the red power terminal, once it's off the controller take some electrical tape and wrap the copper lug so it can't short out on the frame or the negative post. Put the battery back in and flip the breaker ON and the ignition, does the lights and dashboard flicker now or are they staying on? IF they are ON that means the controller is likely damaged and needs to be replaced. If lights are still flickering then it's in the harness or in the battery.

Just make sure that you tighten the main power lugs back properly, you can use a drop of blue locktite on the thread so it wont loosen up overtime. And while your at it , use dielectric grease over the lugs to prevent oxidation/corrosion! On your next big maintenance inspect your connection again.












6) If not then chances are that the issue lies in the battery BMS or the wiring harness in the battery. Dont loose hope yet there is a known fix that you will likelly be able to perform and will be a permanent fix! So far 9/10 times it's this little wire!:

The procedure is on a PDF that you can download here, if you have any questions or unsure about your results please email LunaCycle at , ask for Seb and make sure to write down what tests you did, your measurement and attach photos and videos!


Before continuing with this section make sure you check all the sensors and connections covered here: CLICK ME