Also, the torque converter automatically unlocks when you hit the brake - the brake switch could be causing problems with both the cruise and the TCC.

I have the exact same problem here. In the morning driving to work I have to go on the highway right away and it works fine. On the way home I have to go through the city then onto the highway. It is at this point that OD doesn't work. I haven't gotten around to doing any serious troubleshooting yet. It is nice (not really) to know that other people are having this same problem. I did see a TSB about this and it was the wiring harness within the transmission, a diode that shorts the two wires going to the TCC because the ends weren't cut down and it eventually rubs and expands to short the TCC solenoid.
I should just get off my ^%$ and get the link here...

http://134.39.200.6:9001/servlets/Bl...tmlFile=224670

I don't believe that the transmission will shift into OD without the TCC being locked up and I am fairly certain that the TCC is not locked up when I am having the problem of no OD.

Update:

I Got the coeds pulled today by a tranny shop. I had two coeds
1 torque converter frailer
2 cruise control vent failed.
I did not get the exact # of the coeds just what they said.
They said it could be a gear ratio difference between the Bonn. and the Buick so the computer is not reading the right rpm or it thinks it is slipping the torque converter and then it puts it into limp mode entail you turn it off and restart it thus resetting the computer. Does any one know if I can put the computers from the Buick into the Bonn.?
Can anyone help me find what the gear ratios should be in the Bonn. and the Buick La saber both are 94 I was told it was a direct swap I sure hope someone can help.

Thanks doo700

update:

I got the codes from the tyranny shop.

#300 misfire detected
#561 cruise control vent malfunction
#740 torque converter clutch failure

The names of the codes are familiar but the codes themselves are not. Are they OBD I or OBD II? either 2 or 4 code numbers. Three is not right.

I'm sorry but that is all the tranny shop wrote down on my receipt.
So I do not know if it is OBD1 or OBD2. The car is 1994 Bonneville and the driveline is out of a 1994 Buick La saber.
Thanks for any help you can give
doo700

Okay, OBD I, ie. 2 letter codes...

When you say powertrain out of a Buick, are you referring to the engine and transmission together?

94 and 95 use the 4-digit OBD2 codes.

Your gear ratio may be wrong, but that will only affect shift points. The TCC should still lock up and OD should work fine......as far as I know.

I don't believe the 300, because the 94 FSM doesn't list it.

However:

561 means that the cruise servo is sending the incorrect signal in the vent portion of the device. If there is not a short in the dark blue/white wire, it may likely be the servo.

740 means that the TCC is not locking up when it is supposed to.

okay, I am way off here. Right, 94, 95 the years techs want to forget!!! They never existed....they never existed...