tym t353hst will not start

bjopdlsteel1959 · Oct 8, 2019

Good Morning members, I have a TYM t353hst that will not start just under 300 hrs. Let me give you the back ground. Purchased from a dealer who is longer in business , nearest dealer 70+ miles away. I had an intermittent starting problem. (Which after taking dash apart later, may have been a loose connection to power the start switch) I was probing the three relays in the front of the tractor w a test light to see if they were getting energized. I accidently poked through a hot wire into a smaller wire. started an instant melt down of the harness. After a weekend of rewiring the damage done and with a prayer she started right up. I made to the side of the garage kept it running for a while. then it died again. I noticed one more wire had started to melt the a small black ground wire so I began testing again found where it was shorting out to a large glow plug supply wire. this black wire is the ground to the energizing coils the glow relays and start relays Again made the repair but to no avail. I'm trying to trouble shoot as much as I can before spending any serious money, For example the $350 controller or a new harness 200. I also pulled the dash apart to take look at any obvious physical damage. I did find the crimped wire to the connector which supplies power to the start switch was loose or even disconnected. Which could have been my problem to begin with if it was just loose. That was repaired by re-crimping and soldering.

In the diagnostics in the manual it states if turning the ignition switch to start and you get absolutely nothing the controller could be faulty. At this point I'm just trying to get her to turn over. Unless the glow plug circuit is related, which I do not believe it is. But then again the dreaded Controller???
Is there any way of starting by bypassing the controller? I would think energizing the start relay as well as the run relay. The schematic that I have is terrible very hard to read. The controller pin out shows 26 I get to the tractor there is only 10. Wire colors don't seem to match schematic's even the colors on the start switch different... I'm currently talking to a dealer trying to get an accurate schematic. At this time I've done the following

1) pulled the glow plug relays and start relays and bench tested them
2) checked all diodes
3) verified power to ignition switch (re soldered loose connection)
4) verified power in start position
5) jumped starter solenoid , starter turns

I do hear the controller click on and seem to hold the internal relay for about 5 seconds or so (sealed unit). There are three identical power relays on the firewall . For a while I heard a relay buzzing but no longer. I plan on pulling those and bench testing them all.

I am pretty sure that one of them is a run relay. I don't know if the controller activates that or not.

Any thoughts, Any way of obtaining better schematic?

seville009 · Oct 9, 2019

There’s a wiring diagram towards the end of this manual

https://tym-tractors.com/wp-content/uploads/2015/04/T353-Operation-Manual.pdf

bjopdlsteel1959 · Oct 10, 2019

thank you,
Ive obtained three manuals to date. Still not a one matches. Pretty close to get and understanding of what is going on. Not sure if bad controller will not allow tractor to start.

Gator6x4 · Oct 10, 2019

Sorry about your problem. Today’s vehicles, cars, trucks and tractors do not like test lights. If me, I would get rid of the test light and get a volt ohm meter. Harbor Freight if you have one close or order on line is a good location to look. They have volt ohm meters for any budget.

bjopdlsteel1959 · Oct 10, 2019

I have a very good multi meter. Looking at the various schematics. Confusing because some show the glow timer others do not. I have the parts catalogue as well which depicts the proper connectors for both harness involved. AT this point I'm going to try to determine id this controller is sending electricity to energize the coil of the start relay and then the two glow relays. I am assuming the glow timer gets energized at the same time. my rotary switch has an override to the far left which you can override the timer to energize the glow plugs longer. Thanks for your reply

justman777 · Oct 14, 2019

Have you tried checking or bypassing your safety switches? Any one of them could be the cause of a no start condition.

bjopdlsteel1959 · Oct 14, 2019

Thanks for the tip. Currently I have checked the Brake and seat switches (seat has been bypassed) . On my schematic I see a few more pto and hst switches. looking for them. I did energize the controller and did not see 12 volts which would energize the start relay. I did see a volt or two. MAybe bleed through from a short. I used to hear a clicking relay then a buzzing within the controller early on in this search for my problem, but no longer. , which is sealed. Before I spend 350.00+ on a controller I will cut the top off that controller and look for any obvious damage. Thanks again