Hi...I think that the interrupts used for the MEGA code might be "busy" on the Leonardo because the same code doesn't work.
On the MEGA I was using interrupts #2-5 to read the encoders on ports 18-21. On the Leonardo I'm using ports A2-A5 but the interrupts don't work (maybe they're taken by the bluetooth module or the motor shield?).

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Are you sure you have D1?

D1 : TRAC KO
This alarm signals that the (M11) Master traction logic unit is not comunicating.
Check:
- The supplying: 48V must be present in the connector JT1 pin A1 cable M
- The can-bus connections
If the supplying is ok, but it do not permits the truck working, replace the Master traction logic unit.

1D : left encoder lock

Interrupted or disconnected left motor encoder.
The alarm appears after 10 seconds approximately with the accelerator pedal pressed.
The machine works at reduced speed and at maximum current.
Encoder basic electric diagram.
In picture it is shown only a signal (A).
The encoders generate two same signals, but out
of phase of 90°(A-B).
1. Connect the positive tip of the tester (red) to
the positive one of the encoder.
2. Connect the COM tip of the tester (black) to
the encoder signal (A).
In base of the motor position, it will show the
following values:
* low signal: 0,5 - 1,5 Volt
* hight signal: 10,5 - 11,5 Volt
It is not possible to read intermediate values with
the motor stopped.
If the motor is working, the multemeter will
automatically read the Mv (medium value)
Mv= 5,5 - 6,5 Volt
Carrying out this test directly on the logic
connectors it is possible to determine if the
signals are good (see upper description) or if the
channels are opened or in shour circuit. If the
signals are good, the problem could be on the
electronic control

Hi dear, please do the acquisition in Learning mode. i think acquisition required.

Read on this post. After reading the whole post, we can get solutions to deal with the trouble quickly and safely. Thanks for your nice sharing.

Yes controller is in back of the truck. 2 zapi units and underneath these 2 is the hydraulic unit.

Encoder voltages for one output ia correct whereas the second output is not in accordance with the given values in the service manual.

The engineer hardwired the 3 motor cables and the light encoder wires off to a truck next to it and ran this motor and encoder without any faults.

So we know its not the motor or encoder, its not any of the traction controllers.

Must be a wiring or perhaps there's another pcb it might go through?

Can you please look and give me this info about truck.
Year on plate, batery voltage.
If truck is C3E150 it must be three wheel and motor traction is back in counterweight.

Good morning, have you checked the encoder plug connector connected to the inverter with the correct signals when the machine is on?