[GoAhead92]

My little Wheego frustrated me a bit by dying in the middle of the road yesterday. I was driving about 30 MPH when it lost power & coasted to a stop, not to restart. The initial error displayed 18 overvoltage, while decelerating it went to error 12 controller over current, then showed 14 when it came to a rest. Error 14 = Precharge Failed. IDK if running the heater and a possible heater fault contributed to this problem.
I tried cycling the key on & off a few times, then cycled the emergency cutoff a couple times both of which failed to reboot successfully. Using diagnostic mode, I noted the pack voltage about 109 and KSI voltage 2.2
Instead of main 5 it says main 9 which I must research.
Additional information which may be relevant. 4 months ago, I switched from lead to lithium and now run 110 volts through my 1238-7501.
I successfully made over a hundred trips which I estimate to be well over 200 key cycles on & off with a rare error 18 overvoltage shutoff. It did this maybe 3 or 4 times and always immediately restarted fine.
A month ago, I replaced the main contactor with exact model though the original was fine. I did this not realizing the factory settings to keep the DC DC converter on 24/7.

 

[GoAhead92]

Here’s what seemed to fix the problem. Wheego sent me a resistor to connect across the main contactor. I understand this causes a slight current drain, but that is not yet an issue. Once installed, the controller reboots and seems to be working ok now.
Before the resistor arrived, I’d read that connecting an incandescent bulb across the contactor would serve the same purpose. I tried this and it worked to temporarily get the system working to move the car.
I’d like to know what caused the original piece to fail after over a year of reliable service.

 

[major]

Here’s what seemed to fix the problem. ........
I’d like to know what caused the original piece to fail after over a year of reliable service.

I don't know for sure, but it may be that some high voltage accessories like the heater were overtaxing the precharging circuitry internal to the Curtis causing premature demise. The external resistor across the contactor may be the workaround. Do you have the Ohms and Watt rating for that?

 

[GoAhead92]

Factory said it was 500 ohm 10 watts. Since installed, I have not had any more Error 14 pre charge issues. After installing the resistor, fault 38 welded concactor occured so I replaced the Main Contactor with the same model Tyco. Then, I have had a couple more #38 contactor welded faults which caused it to stop. Since this continued to occurr after I changed the main contactor, I'm frustrated So, now I wonder if the software is over sensitive to some signal. Cycling the key off and on to reboot cleared it. It's disconcerting when the power fails unexpectedly.

 

[honn1002]

Factory said it was 500 ohm 10 watts. Since installed, I have not had any more Error 14 pre charge issues. After installing the resistor, fault 38 welded concactor occured so I replaced the Main Contactor with the same model Tyco. Then, I have had a couple more #38 contactor welded faults which caused it to stop. Since this continued to occurr after I changed the main contactor, I'm frustrated So, now I wonder if the software is over sensitive to some signal. Cycling the key off and on to reboot cleared it. It's disconcerting when the power fails unexpectedly.

When a heater or any accessory is connected the controller's B+ side, this will damage the controller's internal precharge circuit.
The controller faults out a welded contactor because of the 500 ohm resistor that is connected across the contactor. The controller performs a welded contactor check to detect any voltage across the power capacitor bank before it closes the main contactor for safety. The controller thinks that the contactor is welded which allows the voltage going to the cap bank. In your case, the contactor is actually not welded, it's the external 500 ohm resistor that provides the voltage to the cap bank.

 

[major]

........ It's disconcerting when the power fails unexpectedly.

You make it sound like it loses power while you're driving. A welded contactor fault should only occur on start up. Or is the contactor opening and closing off the throttle?