01 Diamante tranny problems - Heater core?
 

Hi, 01 Diamante w/134K miles. No problems at all until this week.

2 days ago, my transmission would not go into drive for 5-8 seconds after starting the car in the morning.

I checked the transmission fluid and it was a little low, so I topped it off - no change.

If the car is "cold" (it is summer), if I pull up to a stop and the RPMs get below 1K, the transmission kicks into N. If I brake and rev it up, it will kick back it.

Once the car warms up (5 minutes) the transmission stays engaged.

I have read about the heater core issue and am wondering if this isn't the issue but I have no wet carpets and there isn't a smell. There is a bit of film on the inside of the window. (but I haven't washed it in a while)

The trans. fluid doesn't smell burnt and is still red.

Any ideas?

If you not have replaced the trans fluid at the proper intervals, replace fluid; only use OEM dealer fluid; do not use trans flush machines with claimed Mitsubishi equivalent additives that shops will tell you works fine; it does not work.
You would certainly smell the glycol inside the car if the film on the windows was from coolant leaking from the heater core seals, so this is probably not the issue.

Pulled error code P10732 - any chance it is electrical only?
 

After months of messing with this, it is at the transmission shop now. They pulled P10732 (incorrect 2nd gear ratio) after "racing" the transmission.

I obtained a second ECU and immobilizer that I haven't put in yet just because the dealer wants $135 to program the keys and I have to tow it over there.

Any chance it is an electrical issue (ECU, input speed sensor, etc) or should I assume this is going to result in a $3K transmission bill?

Thanks.