TCM FG25T3L:
wiring schematic needed

Looking for a wiring diagram for this model. I found one for a fg25t3. It does appear to be different though. This one is a fg25t3L. I am guessing the L is lpg. Which I have. This one not getting power to the relay that opens the gas valve from the propane tank. I have power to the relay coil but not the B+ supply to the relay. Very dirty and rusty hard to trace where the wire come from.
  • Posted 10 Jun 2023 01:43
  • Discussion started by John_Peters
  • Texas, United States
jpeters
Showing items 1 - 5 of 5 results.
I found the problem. I was looking at the wrong relay. After I got it to my shop first thing I did was to power wash under the hood. Looking at the wiring I found that the relays were numbered corresponding to the schematic. I traced the problem back to the ecu and a corroded wire. Some previous tech probed the wires and make really big holes in the insulation. I found several like that. I had to order a replacement connector body and connector pins. I ruined the body because i could not figure out how to remove the pin. I know how now. Anyway poor place to mount the ecu on the frame close to the ground.....
  • Posted 23 Jun 2023 04:14
  • Reply by John_Peters
  • Texas, United States
jpeters
The relay that I am looking at on this machine does not have 2 brown wires. It has one brown one green one pink and I think a gray one. The green goes to the gas valve that goes to the propane tank. Is the lpg intercept valve the one that goes to the tank? And after that I think is the unit that turns liquid to gas. This relay does engergize its coil with the key on.
  • Posted 16 Jun 2023 09:55
  • Reply by John_Peters
  • Texas, United States
jpeters
Relay #4 is for LPG intercept valve will have 4 wires, 2 Brown, 1 Green and 1 Black with Yellow stripe.
Here is sequence of operation.
When the ignition switch is in the start or run position.
The 2 Brown wires will be battery + volts from relay 1 and 2.
The black yellow wire will be Battery + volts from pin 112 on the ECM
The green wire (to LPG intercept valve) will go positive battery + volts.

With the ignition switch is in the start or run position, if ECM does not receive continuous signal from crank shaft position sensor for 6-10 seconds the voltage at black yellow wire will go to 0 volts.

The other wire on the LPG intercept valve will be chassis ground.
  • Posted 16 Jun 2023 01:20
  • Reply by Drlifttruck
  • Texas, United States
Lift Trucks all the same, just painted different colors.
Doc
Email: kulsh@forkliftservice.net
Thanks but that is the same one I have. The relay that controls the gas valve really only shows 3 wires going to it. The power to the relay coil and for the relay contact shows to come from the same connection. The one I am working on has separate power for each.
  • Posted 16 Jun 2023 00:47
  • Reply by John_Peters
  • Texas, United States
jpeters
Here is link that you can view and download required wiring diagram..

https://drive.google.com/file/d/1Ae5xYPKAQC_WpqCIEdrKZxiCmV6ZVG3t/view?usp=drive_link

Regards,
Doc
  • Posted 16 Jun 2023 00:30
  • Reply by Drlifttruck
  • Texas, United States
Lift Trucks all the same, just painted different colors.
Doc
Email: kulsh@forkliftservice.net

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The Michelin Guide with its star rating system originated in France in 1900. The guide was created as a marketing tool to encourage more car travel and consequently increase the demand for tyres. It initially contained maps, tire repair instructions, and lists of restaurants, hotels, and mechanics.