I have an '01 Disco w/ ~140K miles.

Was driving around the other day and stopped in a parking spot with the car running for about 5 minutes. put it in reverse and then drive and the M and S with gear symbols around them starting blinking at the same time. Could tell it wasn't catching like it should I could run it up to 3,000 rpms like it was in neutral and it would barely move the wheels. Stopped the car and restarted it, problem solved. However, a few days ago I was driving slowly through a shopping center and same problem arouse, this time while I was driving about 10mph, idle speed. This time upon restart check engine light was on but transmission worked fine. Next time I restarted, the check engine light was gone. Had not gone to check what codes it was putting out. This has happened a few more times since that day, usually after being parked, and I have noticed that every time the air conditioning has been running. may be circumstantial but I'm sure any detail can help.

Just bought the car last July, put about 10k miles on it. No problems other than a radiator hose leak, and my cruise control doesn't work, seems like a vacuum line has a leak.

Any ideas as to what could be causing this? Is this potentially serious?

Thanks

 

Check your battery voltage and alternator, the transmission is likely going into fail safe mode due to low voltage.

 

Yes, that is the first place to start. Go to your local parts store and have them do a free charging system test, should be between 13.6 and 14.4 volts.
Let us know hat they fine and if you have any fault code numbers.

 

Tes, that is the first place to start. Go to your local parts store and have them do a free charging system test, should be between 13.6 and 14.4 volts.
Let us know hat they fine and if you have any fault code numbers.

 

Battery and alternator are fine, voltage is slightly below 14, around 13.8. Have not checked the fault codes yet. It has a lot to do with the A/C running. I was sitting in the parking lot again with the a/c on and after about 4 minutes it started flashing again and went into fail safe mode. I sat with the car running for about 5-10 minutes with the A/c, radio and everything off and then restarted it and it was fine. It sure sounds like a battery problem, but not according to auto zone. Although i must mention, it read the battery went down to 16% all of a sudden, the A/c was not running at this point. We re-did the test and it was all fine, maybe just a coincidence. Any thoughts?

 

Go check your battery and voltage. A/C will draw down the voltage. Its a free test at a parts store. You should read 13.6 to 14.4. Check with the A/C on and off.

 

With everything that came from the factory turned on, volts should not drop below 13.2 at idle. With just bare minimum on, more like 13.6 - 14.4. A drop below that can indicate a weak alternator (bad diode) or a weak battery (dead cell, but that shows up on starting usually). Also loose serpantine belt.