Uhm, great ideas all, but maybe best to just tell you what I've found out today.

First of all, on a good car, you can watch the main contactor and brake leds, on the HCB board. When both the leds are lit, that means the drive is on, (201 picked), and the main brake coil is picked.

When a good car comes to a stop, you can see a very obvious delay, where on the HCB, the main brake led goes dark first, and then the main contactor led stays up for just a little bit, before also going dark.

On the bad car, the leds on the drive HCB board are doing EXACTLY what they are doing on a good running car. It is the intention of the drive to keep the motor torque up for a bit, while the main brake sets.

That's it's intention....good intentions...

But that's not what is happening with the output of the main brake power supply, and the 201 main contactor.

What the bad car is doing is this-

The main brake pick command, (24vdc, referenced to ground), is fed from the drive HCB board, to xb2-7 pin on the main brake power supply.

On a good car, when this main brake pick command goes low, the output of the main brk ps drops out immediately. No command, no output.

But on our bad car, when the main brk pick command drops to 0 volts, the output DOES NOT TURN OFF right away. It takes a few milliseconds for the output to turn off.

So the drive has the intention of dropping the main brake first, before removing the motor torque,

BUT-

The main brake power supply is schizophrenic, and marching to the beat of it's own drum. Our brake voltage decays simultaneously, with the drop of 201, and removal of motor torque. This must not be, because we need the brake to set before the removal of motor torque. Otherwise, it will roll-up before the brake sets. Which is what this car is doing. No no, can't have it this way. MUST drop brake voltage first, before the drive shuts off.

There is a pot inside the main brk ps, located on a timing relay (416), but it's only purpose is "economizing", or reducing the brake voltage during a run. THink of it as a cooling resistor! Tried turning the pot anyway, had no efffect at all.

Tomorrow, gonna take the main brake power supply out, and swap in a good one, see what happens.