The LT42e Chronicles: A Tale of Wires, Woe, and Mild Electrocution

[jwax]

Live in a swamp, so no nearby cliff to push it off of.

 

[jwax]

I notice the XT1 wiring diagram is missing some components like the motor controllers, 20 Amp fuse, and the 4-pin CANBUS connector on the battery. Are there other schematics from your source? Thanks again!

 

[odonnse]

The wiring diagram is just for the main harness. The motor controller power comes from the PDM. And the CAN bus connector you see in the drawing is what connects to the CAN bus harness for the motor controllers. But the main harness connects directly to your BMS with a deutsch style connector.

 

[jwax]

Thanks for the explanation, but what is the , "PDM"?
Also, do you know what this black odd-shaped box is? Has a 4-pin connector, a 12-pin, and the large power cables.

 

[odonnse]

I believe that is the PDM (Power Distribution Module). Your earlier system looks a bit different than mine, but I believe that is it. That is what houses the contactor that gives the "click" when the VCM (Vehicle Control Module) says everything is good. If you have error codes, most of the time the VCM will not give the PDM the "go for launch".

So just to get is straight, your charger gives you an error code and your VCM gives you an error code? Can you share an image of those or share what they say? Also was the battery fuse good?

 

[jwax]

Thanks! There's no code from the VCM, or the mower. The mower simply does nothing with the switch to ON.
The only error code is from the Delta-Q charger- E004

Tempted to gut the wiring harness, and use 48 volts to the blade motor, and the drive motor controller to drive the drive motor. Simple!

 

[odonnse]

I would be reluctant to do that, easy way to cause a catastrophic failure of your batteries and start a fire if you are not careful. Does your VCM turn on at all? It is odd that you are getting an error code on one thing but not the other.

 

[jwax]

Never have seen an error code on the simple little display on the mower. Just, "Depress Brake Pedal", "Close charger Door", etc.

Anyway, it's done- spent this holiday gutting the wiring. Down to a cutter motor, and a drive motor. Now just need to drive the two.

Interestingly, both motors are labeled, "48 VDC", but wires/controller are obviously 3-phase. Curious!

No, VCM never activates.

 

[odonnse]

The motors are most likely DC motors. The motor controllers will drive a square wave to alternate per phase of the motor based on the speed input provided. Obviously the blade motors will be driven at a constant speed and the drive motor will be variable. I guess your model version has some more differences than I expected. The VCM provides most of the system error codes.

 

[jwax]

Correct! Found they are Brushless DC motors (BLDC), requiring 3 inputs to drive it. Now to figure out the Hall-effect wiring which is necessary for the controller to control speed.
What complicates this relatively simple concept of battery and motor to make things work is that pesky CANBUS. Don't need it, don't want it.
But seems every part of the mower is dependent on its hidden signaling. Not my mower. not any more.

Waiting to see schematics from ASI controls, who built the controllers. Then I can put it all together.
Delta-Q charger already told me their charger needs CANBUS signals to output a charging voltage. I have other chargers.

Thanks for helping, and following along!

 

[odonnse]

Wow, you have really dove in! I appreciate the initiative and good luck on your goal, let me know if I can help. Not sure about your system, but on the newer the motors themselves also communicate over CAN. Really the only thing that does not communicate over CAN is the PDM, brake switch, TPS (throttle position sensor), and seat safety switch.

 

[jwax]

The motor controllers need the CAN to enable motors, but my motors themselves don't appear to be involved. Seem to recall this old boy was made in 2018. Will keep you posted!

 

[blades]

Those hall effect circuits are noted for failing across everything they are put in. Kinda like when mosfets first appeared. If you looked at them cross-eyed they failed, or the cheap capacitors used by one particular computer mfg in 90's.

 

[jwax]

You have obviously been in the electronics repair business by your comments- me too.
Next I have to figure out the wiring of those Hall effect devices from the wires coming from the Deck motor. Then I could use a generic BLDC motor controller. ($50). Any ideas on how to identify those wires? There's 6- Blue, Green, and yellow (the three phases), Black and Red (5 volt power), and a White. What's could the White be for??

 

[blades]

possibly voltage limit /gate control, not every thing works on 5v, some areas only range from .5 to 1.5v,

 

[el33t]

You have obviously been in the electronics repair business by your comments- me too.
Next I have to figure out the wiring of those Hall effect devices from the wires coming from the Deck motor. Then I could use a generic BLDC motor controller. ($50). Any ideas on how to identify those wires? There's 6- Blue, Green, and yellow (the three phases), Black and Red (5 volt power), and a White. What's could the White be for??

Temperature sensor?

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