Transmission or hopefully a computer update?
 

I have a 99 s80 t6. The other day when I was driving the car started accelerating with hardly any power. The "service transmission" message came up with the yellow triangle on. I checked the fluid and it was good. The codes that came up were:
P0743
P0758
P1618
After looking them up it was all electrical. I cleared the codes and everything went back to normal for about 10-15 miles.
I was thinking it was more a computer issue then a transmission problem because after clearing the codes everything was fine and I'm thinking that if it was a transmission problem it would be all the time, codes or not. I'm still new to the whole full computer car so I don't really know. I saw that P1618 was a bad connection (I think). If that's the case where would be a good place to start looking?
Would a computer update at the dealership fix it??
Thanks for your time and help.
John:confused:

Any feedback on this? I am troubleshooting what originally presented itself as a Speed Sensor failure. I am getting ready to start up a separate thread. I'm driving a '98 S90.

Nothing yet. I'm hoping soon. I would hate to let a shop figure it out at $80+ per hour. I've read similar things that all lead back to the computer, but I want to make sure if my particular problems mean the computer.

Well. I took my car to the dealership, so they can hook their computer up so I can get a more precise code reading so I could know exactly want needed to be done. Well, it was not the computer. It was the lock-up solenoid and shift solenoid 1-2. So this should be a ton of fun. Haha!! The Volvo repair manual says it should take 7.5 hours. I guess I'm looking at about 12. Hope this fixs the problem. If anyone has any tips let me know.
Thanks.
John

I have the same problem on my 2000 s80 t6 (4t65e) I replaced all the solenoids in the side pan and still have the same problem. Runs and drives perfect, shifts perfect for a few miles then limp mode. p1618 and S1 shift solenoid hydraulic fault. I'm replacing the tcm next unless I hear a better resolution.

That's a possibility. The TCM is coded to your VIN, the one you replace it with may not work until it is program by someone like xemodex for $329 plus shipping.

I have never seen a bad TCM, and have seen many of those GM transmissions that are bad. Do you have the capability (or desire on a 23 year old car) to overhaul that GM trans if needed?

you may want to start by cleaning the connector & electrical contacts of the TCM. Can't hurt and is something you can do yourself. We had some shifting issues on our 2000 S40 and that cured it...