Motor Controller -51 error code

I bought a 2002 last year at a UCR (University of California, Riverside), auction. Upon getting it home I found it had a shudder during deceleration. Thinking it was half-shafts I have replaced both of those plus put new tires all the way around. The shudder persisted. Then I read about the bushing that sat between the motor and the differential. So I replaced that, but in doing so I made a mistake by not having the main switch to the batteries turned off. I had a momentary spark and now I get a -51 error code. I have power all the way up to the B+ side of the motor controller.
On page 5-9 of the manual, (Step 6), it says that if the voltage is approximately 72v, replace the controller. As I am getting 72.6v I’m guessing that I’ve toasted that pup. To complicate matters I can find no fuse short of the 400v main battery fuse and some 3, 5 and 10v ones on a block on the other side of the firewall/divider. BTW, I have no circuit board to speak of. I’m presuming that the maintenance guys at the UCR yard got rid of that and put in some sort of work-around.
I have tried to “reboot” the controller by draining the power. I have tested all the fuses and they check out okay.
Is there a way to test the controller?
Assuming that the controller is toast, where’s the best place to get a) this one fixed; b) buy a used one; or c) fork out the bucks on a new one?

At this point I’m really hoping that someone wiser than I will step up and say,
“Gee, you don’t have to do that! Just press the [insert item here], hold the thing-a-ma-jig and jiggle the perpendiculator.” or something along those lines.

By the way, the old “bumper, resilent”, was pretty chewed up and I’m hoping that this will solve the shudder. I won’t know until code -51 is resolved. I am though getting quite an education in Gem car technology. I have great hopes of being able to begin hacking this one, but first I have to get the @#!K&%! thing running! Help please!!!

The manual says “motor controller voltage low electrical fault check voltage, see
manual,” which doesn’t say much. There are companies that inspect and test GE motor controllers. There is Ride For Fun and several others.


Thanks Daniel. What the manual lacks in specificity could fill an encyclopedia. If I can paraphrase Yogi Berra, (or was it Casey Stengel?), "Da’ information is staying away in droves."
I’ll be yanking the motor controller out this morning and and cracking it open to see if I can ID any problem visually. It’s not like I’m bound to void the warranty, is it? The fact that I don’t have the much described circuit board is troubling, as I would very much like to find a fuse, (short of the 400 amp baby) that was blown. I did notice it has two spade type auto fuses in one corner of it in a photo of it. More to follow…

What exactly do you mean by “not having the circuit board?”

If you look at page 5-18 of the service manual, there is a diagram in the left column that designates 1) motor controller, (mine’s a 353T1), 2) battery charger, (which for me is a Zivan NG1) and 3) PWB, (Printed Wiring Board). I don’t have a PWB. In it’s place is a Sure Power Industries Model 71030i converter (?).
On the other side of the bulkhead, (it’s not really a firewall per se), under the splash guard is what I believe an add-on fuse panel for automotive spade fuses. The panel has qty 3: 3amp, qty 2: 5 amp and qty 1: 10 amp, all which seem to be in good condition. (not burnt.)

I have also retrieved the 353T1 out of the vehicle. Is there an easy way to get a look inside of it? It has black plastic plates over each end which when removed have a secondary black plates under them. I am reticent to bugger those up to get a peek inside, but seeing as the prices for a replacement unit is running between $400 and $500, that sort of cash is a big incentive to see if I can get in it, especially since there is no warranty to void.

Any help or advice would be greatly appreciated.