Thermo Start Light

Scotty Dive · Nov 25, 2013

I have what I believe is a light that is the thermo start indicator light - mine does not work. I actually thought it was for illuminating the gear shift when the headlights were on.

Can anyone tell me what it is actually for? And - if its the thermostart light - how does it work? In other words, the manual says to hold the key switch to TS to begin the heating process. The light will go off when you are ready to start the tractor. How does the thermostart provide voltage to this light?

winston1 · Nov 25, 2013

Scotty, I believe you are correct about that white light. I believe that is just a work light to illuminate the gear shift, etc. My 2002d has one just like yours. It comes on with the light switch.

I do have a red light up higher that did come on when using the thermostart. You can see both lights in the picture. The other picture shows the little black box beside the regulator. My red light did not work when I bought the tractor although the thermostart did work. At one point I took the little black box apart and found something loose. To long ago for my old mind to remember just what. I know I soldered something in there and the light begin working. When holding the key to the left it would come on and go of automatically a few seconds later. Just guessing 10 to 15 seconds. The light has quit again although the thermostart continues to work. The parts manual for my 2002d shows this on the thermostart page with part number 121474-77920. Description comes back as a timer.

Scotty Dive · Nov 26, 2013

Well - thats interesting Winston -

So - I do have a missing light near the the key switch and I do have a similiar black box in the engine compartment - wonder if I am just missing the light?

winston1 · Nov 26, 2013

Do you have a parts manual for your 2020? If so, check the thermostart page.

winston1 · Nov 26, 2013

I went out and looked at my black box. I can make out WI1-07 and Japan. It has three wires coming off of it. Red, black, and yellow.

Scotty Dive · Nov 27, 2013

Winston - Looks like I have the same black box. I did not remove it but saw no numbers on it. Wonder if it works??? Any idea what I should expect in terms of voltage across those wires? BTW, it does show up in the schematic too. I haven't had a chance to look at the wiring schematic but those are in Japanese so its kind of tough figuring it out. It will be easier to see what wires are behind the ignition switch where that thermostart light would live.

winston1 · Nov 27, 2013

As I stated, my light is not working right now. I went out and tested with black test probe to a ground. Red to wires. There is no voltage at any of the wires until the switch is turned to the thermostart position. Then there is 11.27 volts at both the red and yellow wires. Nothing on the blue wire. I held it in that position for at least 20 seconds and nothing changed. That sort of indicated to me it is not working correctly. The thermostart element heated up, by the time I turned it off the manifold was good and warm at that point. I did have 12.6+ battery voltage.

When I get adequate time I may take my box off and take another look in it. I'll try to remember to snap a picture of the innards.

Scotty Dive · Nov 27, 2013

Thanks Winston. I had a few minutes today while it was still warm enough to be outside...I did some digging under my dash - mine is covered with panels and was hoping to find a bare wire with a plug where the TS light would be - no luck....but just for grins I looked up on the opposite side and I could just barely see a bulb tucked way up behind more wires....I fished it out and pulled it over the steering column and it clearly is the TS light. Bulb is still good but it does not light up. Still trying to figure out how it stickes out through the empty hole in the dash as its way to big and I am clearly missing the red lens too. TS does work and heats up in the intake. I even got curious and removed the black box (no numbers anywhere on it) and popped the top to peer in. I have no idea what I am looking at when it comes to circuit boards, but nothing looked broken.

Neat 1500 · Nov 28, 2013

I imagine it would go like this - RED is supply from TS position
BLACK is earth
YELLOW is timed supply to lamp which should extinguish after xx seconds.

As it does not actually drive the TS plug i dont know why they went that way in designing it?

winston1 · Nov 28, 2013

Here is a shot of the other side of the circuit board. Pretty sure our boxes are identical. You might be able to see where I soldered the middle post on the little black box in the upper right corner. It went to working for awhile but has since quit. It is all over my head now as I don't see anything physically loose or broken.