2016+ 72v conversion

Several members are starting 72v coversions.
Moving some of the messages to here.

Those of us that paved the way are doing it the same. I’m sure there are simpler ways by programming can control. I’m a hardware guy, so this is how I did it.

Swap Sevcon controller to a 80v s4 gen 4.
Program coil driver to 48v. Use one 48v contactor wired as built.
Program for dual throttle cloning a Ranger Ev. Uses same throttle.
Program for wired direction inputs.
Throttle p22 and 23, f-p18 and r-p30 needs hard wiring.

Not a difficult wiring job. I will make a harness available for $150.

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Starting over on my 2018.
Step 1

Loosen lower dash and unplug throttle.
Push throttle plug back to under hood.
Plug supplied extension wire into throttle.
Route it back under hood to original plug with the new connection near Sevcon.

Step 1-b
Connect (pin )throttle to Sevcon pins 22 and 23.

This is Exactly what I was looking.

Pin new throttle and direction wires.


Switch end violet F and yellow R.
Cut at switch and connect diode logic block inline.
SW mark (cathode) goes to switch.


Wire from Sevcon must connect straight through to switch. (diode in line under shrink tube)
Cut wire from Gem ecm must go through diode to switch.
Sevcon supplies 50v active low. Gem 12v active low. Diodes keep 50v from back feeding into Gem ecm.


Original Sevcon controller is subject to many unknown whims from ecm. If there is trouble keeping the controller powered, connect the coil of control relay direct to switched 12v.
Relay coil wires are small red and brown. Cut them leaving enough length to connect new wires.
Wires from ecm are not used. Tape them off.
Other end of harness connects to switched 12v.

This harness makes it easy.


Switch wiring per @djgabriel2004

DCI method of connecting dc systems.

If your car did not have an aux battery, 12v was supplied from traction battery tap through a large red wire.
I cut that wire under the hood, leaving it long enough to reach the DCI plug, for constant 12v.
Switched 12v from DCI goes to the dc-dc plug when removing the 48v converter.
The only place to connect the control line to DCI, that is free from “polaris”, afaik, is the wire from key switch that goes to vcm input.

Testing and connecting dual throttle:
Test wires
One throttle is .5v, connect to p23
One throttle is 1v, connect to p22