Horizon CT12.1 Treadmill troubleshooting. (SJED08066AA PWM controller JDYF01L)

Thread Starter


Joined Jan 1, 2017

I found this site while searching the web for information for troubleshooting a treadmill problem.

The treadmill is a Horizon CT12.1. I believe it is made by Johnson Fitness and labeled under a couple different names. Another version of this is the Livestrong LS12.9T I'm thinking the CT stands for a Canadian Tire, a store in Canada that sells(sold) this model.

It looks like the one shown here. http://www.runreviews.com/wp-content/uploads/2011/03/horizon-CT12.1-treadmill-review.jpg

Now on to the problem.

With the unit plugged in, I can turn it on and the unit appears to go into its boot up state. Three long beeps and the center screen displays "301 01" on top line, "MILE" on second line and "CT" on third line. Then two shorts beeps and all indicators and leds on control panel light up. After this nothing can be controlled. Every startup is the same.

The first thing I though is this might be related to the safety key. It is a copper tab type key that slides into a set of contacts to close a contact. It had a very high resistance on some inserts and no resistance on others. Cleaning the copper key and contacts brought it a clean closed contact every time, but with the same start up results. Not the safety key.

Next was to take a fast look at the two boards. The upper control panel board on visual examination looks to be ok. No obvious signs. This board is marked
SUH08012PB (DT999&1399) BY TFJ 09/03/26 All conections appear to be connected.DSC_0448.JPG

The PWM controller board is marked JDYF01L Johnson Fitness on the pc board and there is a label on the heat sink (which is part of the board assy.)
Marked 2.75 HP 110V JC02-001 SJED08066AA Ver H102S101 JC02MC100aa005278. It appears fine on visual inspection also.


There are five red leds on this board. Four in a group. These four do not light up at any point in the boot up sequence. Two of these are labeled UP Down. Probably for the incline actuator.

The fifth LEd is behind the three large capacitors and can not be seen in the photo. It lights up on power up and remains on. From reading I believe this indicates live rail voltage. After power down it remains on until the circuit bleeds down.

There is a 12 wire harness that runs from the control panel to the PWM controller board. Seeing the treadmill has a tilting stowage function, I figured I would check the harness. There are no opens lines on any of the 12 wires from the control panel to the PWM controller.

This 12 wire harness appears to be common on a fair number of these types on controllers. Does anyone know what each line is for? I'm sure a couple of them are power. If you unplug the 12 pin connector and try to power up the unit nothing happens on the control panel at all. I was curious because I had seen a smaller board near the PWM controller that was directly connected to the 120V in and it had two wires coming off of it and up to the upper control panel. I assumed it was the power source for the upper control panel.


I'm sure that upper controller board is looking for certain things in it's boot up. I just have no idea what they might be. It would be nice to know what data is on the 12 wire harness. I've looked around and it appears these PWM controllers are common, but no pin outs. If I was designing it I would most likely have one line as a heartbeart, if it wasn't there I would not let it boot up. A couple more for the PWM signal?

Any other ideas?

Thank you in advance.


Thread Starter


Joined Jan 1, 2017
Well, three years later almost to the date and I figured I would give this a try again. This unit has been sittting idle in my garage.
Anyone has a schematic of the JDYF01L control board? I think I'm going to pull the board tomorrow and start going through the components 1 by 1. :)