I'm at my wits end and wondered if anyone could offer some ideas. My 2003 Caravan SE 3.3L has about 75k miles on it and has started acting up. When I put the car in drive and have my foot on the brake, the speedometer needle starts bouncing around from 0 to 30 mph. The car sometimes tries to lung forward during this time. From everything I've read out there in cyber world, this was most likely a speed sensor issue, probably the output sensor. So to be safe, I replaced both input and output. But despite replacing both, the car is doing the same thing! I disconnected the battery for a few minutes to reset the car's computer and the check engine light did go off. But still the same issues of lunging and whacky speedometer. The car runs fine once you start going about 10 mph but at stops with the car in drive and foot on the brake, it lunges sometimes and speedo is whacky. The speedo needle doesn't jump around in park, only in drive. I took it to AutoZone to hook up the computer for error codes, and I received PO700 and PO 720. I DREAD the idea of taking it to a dealer but may have to at this point. Any ideas out there what I should do? THANK YOU!

 

Sounds like the typical output speed sensor headache - erratic speedo with shifting problems. You even have the output sensor code, P0720. Since you've already changed the sensors with no joy next on the list is continuity checks on the wire harness from the sensors to the TCM. If that's all good then the TCM itself is next on the list.

 

Thanks for that quick reply. Hope it's not the TCM because that looks like an expensive part!