I went to see a repo 98 C70 with 168k miles at a local bank that was selling it cheap. It was very clean inside and out but the upshift arrow was blinking and it only had third gear. Is this a problem that probably requires a new transmission or could it be just an electrical control glitch? If I disconnected the battery to "reset" the computer would that do anything?

 

Have the codes pulled and Cleared. It could be something very simple.

Anytime the Trans computer see a fault it goes into Limpo home mode.(What you see only 3rd Gear or always start in 3rd then changes to 4th after driving.

 

Can my generic OBDII scanner get those codes?

 

Some can and some Can't does it read Transmission codes?

 

I got it when OBDII just came out 10 years ago so probably not.

 

Maybe Auto Zone can if you live close to one.

 

I was able to get codes P1618 and P758 which relates to shift solenoid B electical circuit. How hard will it be to access the shift solenoid. The manual says among other things to drop the subframe. Looks like a real PITA.

 

Yes it is a Pain Clear the codes and see how fast they come back.

 

The codes come back instantly.

 

I will have to try doing some checking.
Usually it will take a little bit to come back. But instantly maybe a wiring problem.