Gen 2 learn trouble

Have a gen2. Here is the deal. Car will run fine from all floors with the exception of bottom floor. Whenever we run to bottm get a ntb input error. Ntb signal is working so i decided to do a learn run. Very strange problem. The learn run will start and learn first floor fine. It will then keep counting until it gets to around 2600 counts. Then it will skip to 420,000 and continue counting fine from there. It wont complete run. Any way i can run on inspect and monitor position and slow car down to 10 fpm and watch the pos count properly until it gets to 2600 the next pulse pos jumps to 420,000. If i run down it will g from 420,000 to 2600 and count fine. Any ideas. Thinking maybe mlb board or cpu

Bad encoder? Turn your inspection speed back up and make sure it's running the same speed in both direction. On inspection and normal speed. The speed of a gen 2 shouldn't vary more than 2 or 3 either way.

I assume you have tried the Learn Run more than one time? With the same result? The Gen2`s is normaly pretty stabile with the encoder feedback...
Mlb board is my first thought...

thanks guys, got it, magic the speed was exact in both directions, i knew it was not the encoder, as it would count perfectly, except for the sudden 400,000 jump in the count.
alex, i thought the same thing, gotta be mlb board or cpu, turns out it was corrupted Dallas Ram chips on the cpu board that mounts to the mlb board. i did not have new chips, so with some advice from a friend, i swapped the 2 chips with each other, after that, the learn run went perfectly and the car is back in service. Now I'm ordering some chips. that was a strange one

I was going to suggest that also but I couldn't edit my post. Those batt Rams do that on occasion swapping them usually does the trick. Glad you got it. Those chips will also lock up and give you floor position fault when all your sensors, inputs and voltages check good.

Just battled that same problem. Are you saying you swapped with another car and then both cars worked??? I replaced them, that would have saved me a day.

no just swapped the chips on the board, 2 chips side by side, just swapped positions of chips, car still working

No Sh*t! I was told the chip was not "bad" just glitches or something and could be burned as a backup after the new chips were in and adjusted. That's great, thank you.