Is the consensus that one -66 is the beginning of the end

GEM Forum
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Thanks for the feedback guys and offer of parts Byron. My neck is still sore and eyes wonky from just driving it home backwards. I didn’t want to be wrenching on it in front of someone’s house and at 8a Saturday morning there are few on the roads and fewer on the side streets.

Plan for today:
1-disconnect field winding and see what controller says in forward
2-measure the field winding resistance and compare to the one Scott loaned me.
3-punt according to what 1 and 2 reveal. j

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Great! And I wasn’t done filling up your Venmo.

@dougl - Order 66 refers to a directive that leads to the killing of the Jedi order in the Star Wars universe. Depending on what side you stand on you might want to watch your back. (make sure your batteries in your saber are charged up).

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ok, got it. All I know is “Luke, I am your father.” and “It is the way” along with JarJar was annoying.

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  1. Testing with nothing touched yet: With the key off I measured 78V from chassis to F1 and from chassis to F2. So this points to a controller issue.
  2. I disconnected F1 and F2 at the motor and measured 78V to chassis on the wire ends. Again pointing to a controller issue.
  3. Turned the start key to ON, release E-brake, put direction switch into Forward position then depressed the throttle. Display shows -66. Controller forward field drive FETs seem to have shorted out.
  4. I zeroed my DMM ohm setting and measured 1.1 ohm across F1 and F2 on the motor and infinity from F1 or F2 to motor casing.
  5. I measured 1.1 ohm across F1 and F2 on the motor Scott loaned me.

From what I’ve gathered in searching, people have repaired the T4/T5 type controllers for shorted field drive FETs but I found nothing on fixing T2 controllers so tracing out the field circuits will have to be done. I don’t imagine there are any copies of a T2 controller schematic running freely on the Interweb?

I’m going to pull the motor, remove the rear case cover and extract the rotor to inspect and see if anything looks funny with the field coils like signs the rotor contacted the field windings. SOMETHING caused the FETs to fail. Could be a physical shorting of the field windings or maybe they just gave out with age and lithium batteries and regen at the time was the final straw. IIRC I had just went from throttle to regen at the point where the -66 error was thrown.

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This is promising. But you really need a Megger to determine the insulation leakage properly .

2 Likes
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I am a bit confused as to how F1 and F2 are measuring 78v with Ref to Chassis GND.

Are the FETs shorting to GND through the controller?
I’d try removing B+ and B- off the controller and check B+ to Chassis and see if there is still 78V.

I guess the next test would be if there is connnect from B- on the controller to Chass GND.
Maybe disconnect the 23p also?

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Ya that has me confused too. I will trace that back to be sure it’s a short in the controller since chassis should be isolate from B- and B+.

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After all kinds of DMM measuring up at T2 between battery cables, frame and contactor(B+) I got down to the fact that there’s 26K ohms from the motor A1 and A2 terminals to the chassis/frame. This seems odd that it is the rotor which has the path to the case but could be carbon or something to do with the brushes.

The T2 still throws the -66 with the motor completely disconnected and I don’t see any measurable voltage from the frame to either B+ nor B- when the motor is disconnected.

So ya, it is likely both the motor and the controller are KAPUT.

FYI:
with only the F1/F2 terminals disconnected at the motor:
F1/F2 to Frame(neg) = -78.0V
Zivan+ to Frame(neg) = 3.4V
Zivan- to Frame(neg) = -78.1V
T2- to Frame(neg) = -78.1V
T2+ to Frame(neg) = 0V
Contactor/T2+ to Frame(neg) = 0V
Contactor/B+ to Frame(neg) = 3.4V

When I removed B-(only) from the T2 I got all 0V but for this:
B- to Frame(neg) = -80.3V
Note: some 0V readings were decaying voltages(capacitor) below 2V so listed as 0V