LED Light strip connection to RAMPS v1.2

I am attaching a 12 V LED light strip ordered from Farm Bot to my V1.2 electronics. I tested the light strip on the input terminals for the RAMPS card to verify the negative/positive. All works fine. Light worked in test. (blue is negative, brown is positive on the kit supplied)

I attached the wires to the terminals for PIN 8. (10 is Vacuum, 9 is water) I added the peripheral in the Controls tab on the web interface. Lights do not work, The other 2 peripherals still work. Motors still drive. Camera works. All systems normal except Lights do not turn on/off.



Hi @John_D

I can send you a photo of my wiring when I am in the office on Monday (I installed strip lights on one of my 1.2 bots also).

To verify I am understanding correctly:

  • You’ve verified that the lights work
  • You’ve verified that your setup can toggle peripherals

If you have a voltage meter available, did you check the voltage on the terminals of the RAMPS board?

I will be able to provide a more detailed response on Monday. Thanks for all the details.


  1. I tested the LED light strip before installing it to verify which conductor was positive and which is negative. (on the shipped cable blue was negative, brown positive). The lights did work when connected to power.
  2. I installed the LED light strip conductors to the RAMPS card on the output + - terminals of P8.
  3. In the my.farmbot.io Controls page, I added the Peripheral. Named it “Lights” and set it to Pin 8.
  4. I tested the toggle button in the software. The lights did not work.
  5. My peripherals on P9 and P10 work fine.
  6. Verified that all other FarmBot functions were nominal.

All I can think of is that the Screw terminals on the card have a bad connection to the RAMPS printed circuit board.

Took out a voltmeter.
Input voltage to RAMPS cars is 12.05V
Output at P-8 is 0.9V whether it is toggled on or off.
Output at P-9 and P-10 is 12.0 V (and there are LED indicators on the card for when P9 or P10 is on. Can’t see a LED assigned to P-8.

Removed RAMPS card. Inspected for damage. No damage observed. Farmbot electronics reassembled. Ops normal except for P8 and LED light string.


RAMPS pin D8 is powered from the secondary power input on the RAMPS board, while D9 and D10 are powered from the primary input. Do you have 12V power connected to both power inputs?

Well. @Gabriel, that would seem to be the issue. In the V1.2 assembly instructions it did not have me make a connection to the secondary input on the RAMPS board. FarmBot did provide an extra cable to connect there but I thought it was redundant like many of the pin connectors. (especially since the instructions did not reference it clear enough for me: “Hey dumb mechanical engineer (that’s me), if you want electrons to flow to a light one day, you need this cable installed now.”

I have 2 choices. I can insert that cable into the carrier, or I can run a jumper across the terminals on the RAMPS board. If there is enough capacity in the single cable to run the lights, too, the jumper would be a preferred solution. Otherwise I need to open up the cable carrier and string the new cable.

@Gabriel, what do you recommend?

To isolate and provide as much power as possible to the rest of the system while the LEDs are on, I would recommend using the second wire. However, if you find it runs well enough using a well-sized jumper that it wouldn’t be worth the effort of running a second wire, I’ll leave that up to you.

@John_D Now that I am back in the office, my memory is a little bit clearer (I installed LEDs on my 1.2 bot almost a year ago).

Below is a picture of my LED strip setup on a 1.2 bot:

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Lights are working. All is good.

Looks great and glad to hear you’re up and running!