66 error code

GEM Forum
42

Took it out for a 3 mile run, all was good until the last half mile and everything shutdown, No dash display, no nothing, then error -15. Reset the master breaker and all was good from there. I don’t think this is controller related. It might be the cheap Chinese BMS, I am about ready to remove it and see if things stabilize. When I got back to the house I checked the voltage over BT and I was at 96V so I was defiantly not low on voltage as the error said.
Bottom line, I think WE fixed the controller !!!

I can;t add anymore replies until someone else posts so I added it here:

@Inwo
Bypassed the BMS, left it connected but also added a cable directly from -B of the battery to the -B controller cable, so I can still montior the cells and balance if needed but the BMS can’t stop the car from running or stop a charge, but I don’t need it for that.
Drove 5 miles, no issues. Things are looking peachy!!
Awesome work Dave!! and thanks for the insight.

@diymatt @milleniumdawg - Looks like maybe we can fix these 66 errors.

43

This is weird, I Let the car for a day, with the master breaker off, went out and tried it, worked perfectly… who knows!!!

44

@grantwest
Look here for -66 help.

45

@grantwest @Inwo
Don’t know where the above came from? But Grant if you need a set of mosfets I have a set on the shelf - all yours. Was going to fix a T4 but went AC instead.

46

I have a 2008 that has a T-4 that is gonna stay DC my 2016 is gonna be the AC beast

47

So you don’t need the Mosfets?
I also have two T-4’s for sale…
I can’t wait to see your 16’ -
My 08’ will soon be “Beast 2 - Tesla powered” :slight_smile:

48

I’m gonna crack open my T-4 and see if the Mosfetts are blowen

49

Pictures above should help. Use ohmeter on all combinations of the three leads. Look for a difference between devices. Zero ohms between any is a sure sign of shorted mosfet.
You can also use “diode test” anything lower than 400mv is most likely a short circuit.

Be mindful of to-220 tab mounting, if insulated electrically from heatsink, and heat conductive pad or grease on same.

50

@grantwest
I had a hell of a time testing them while still on the board. If it is a -66 error just replace all six Mosfets and you should be good.
Like I said, I have them (eight I think) and the insulators still in the box for digikey if you need them.

51

Or send it to me and I can try and fix it up, if you are not good with the old soldering iron.

1 Like
52

Congrats to @grantwest - he is now in the “I fixed the -66 error code on a T4” club.
Good work Mr. Grant!!!
@grantwest
@Inwo

1 Like
53

I purchased an E825 today, 20 minutes in to driving it down a hill it started flashing and now I have error code -66.
I would like to have it repaired (sounds like mosfets) or find a PERMANENT FIX.
Is there a solution for this issue?
Thanks in advance.

54

What controller are you running?
All the repair info is in the tread. The repair is permanent if done correctly, or you can replace the controller.

1 Like
55

Hello, I have a 2002 Gem E825 with a code 66, Are you able to replace the mosfets? Thank you, Scott

56

Thanks! it is a Gem T2.

57

Oh, I think you will want to replace your controller - I don’t think anyone here has repaired a T2.

2 Likes
58

@DelThink
You can try FSIP.biz, they rebuild controllers.

59

Thanks! Talking with them now.

60

Okay, I pulled my controller out and sent it to FSIP they rebuilt it for $440. I just put it back in and I still get error code 66. What are my options here? Thanks in advance.

61

A couple gallons of gasoline and a match?

Call FSIP about the repair. You wouldn’t be the first member on here who had to send their “repaired” controller back to FSIP to be re-repaired. 20 year old high amperage DC controllers, sometimes they miss things. Sucks, but not sure if there is anyone out there that rebuilds these.