96 series 1206 controller

[Timberwolflt]

I’ve got a cart here that doesn’t move... unusual problem I know... JonnieB occasionally shares a “must be hot to run” diagram for various drive systems but I can’t find it... anybody got a clue where I might find it?

96 series 1206 controller

Thanks

[Andy4639]

This should be your schematic per your picture.

[Timberwolflt]

Yes... thanks a bunch... that is the correct diagram but JohnnieB and/or ScottyB have the diagram highlighted in red the wires that are supposed to be hot to make the cart move... looking for that one and where to go next if those all test like they’re supposed to

[Timberwolflt]

I am however a little confused as to why that 1206 shows 4 large terminals instead of 3

[Timberwolflt]

I’ve done some testing as per ScottyB’s instruction.... I think it’s telling me that the F/R switch may be bad... how can this mechanical F/R be bad?... All it does is reverse the contacts... and how do you test it?.... It’s rumored that this is the third one and it’s relatively new... I’m surely missing something

The micro switches seem to be functioning properly

[JohnnieB]

The first attachment is what has to be hot to get the solenoid to click.
The second attachment is the high current (amps) path from battery pack to motor with F/R in F.

The fourth big terminal, labeled A2, is for "Plug" braking, which is used in fork lift applications and other vehicles that are routinely shifted from one direction to the other without coming to a complete stop. With a series drive cart, if the direction is changed while moving, the motor locks up and cart slides to a stop and then accelerates on new direction. With plug braking, it quickly slows to a stop rather than instantly. Direction of travel is not routinely done in golf carts, so EZGO had Curtis remove the circuit in the 1206 controller the bought., saving a few dollars of manufacturing costs on each series drive cart.

The mechanical F/R switch is the weakest point in the series drive. The contacts pass from about 275A with a stock 1206 controller up to 600A or more with aftermarket controllers. The contacts are exposed to the environment and when the corrosion develops they have resistance, so heat is generated. Also, the shift lever is hard to move and moveable cam doesn't always get rotated fully into the mechanical stop, so the current density through the partially engaged contacts skyrockets and heat is generated.

Heat softens the substrate the non-moveable contacts are embedded in, which results in poor alignment and more heat. Basically, the mechanical F/R switch is designed to fail.

Scottie sell the heaviest duty F/R (contact and bus bar size), but if you want to eliminate the problem with the mechanical F/R, stall a reversing contactor.

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Troubleshooting:

Connect your DVM from the controller B- terminal to the controller's M- terminal.

Press pedal just far enough to make solenoid click and you should read fully battery pack voltage (38.2V when fully charged).

If you don't, start tracing the high current circuit path on the second attachment until you find the missing voltage.

[orangeman6]

Getting the solenoid to click with the pedal engaged is the first step. The red highlighted wires.

The f/r has large copper contacts that have to pass the current going to the motor, so they have to be in good shape and line up correctly when it rotates to f or r.

Is the solenoid clicking? Are the cables at the f/r, or the f/r itself getting hot?

[JohnnieB]

Just noticed the charge receptacle only has two wire coming out of it, so your cart doesn't have a reed switch.

The voltage that eventually gets to the solenoid coil, starts with a small blue wire attached to the solenoid's battery side large terminal instead of the reed switch as shown on the schematic I posted. Circuit the same after MS-2.

[Timberwolflt]

The solenoid is clicking

I followed some of Scotty’s diagnostics and it seemed to check out... except he said the B+ to M- throttle sensor test should go from 0 V to pack voltage but the resistor/diode(?) across the large solenoid terminals holds it just below pack voltage but the throttle did increase it to full pack V

The reed switch is bypassed but it’s hot

[Timberwolflt]

I haven’t had a lot of experience with that type of F/R... guess I need to pull it and investigate