More 4+3 issues

Here's a puzzler for you experts out there. I have an 86 w/ the doug nash 4+3. Usually it will engage OD normally. Ie. I shift through the gears and when I let off the clutch the OD will engage. No problems right...wrong. If I rev hard through first hear the OD shuts off as normal but will not re-engage unless i park and turn off the car for about a minute. After that it works fine again. Unless I get on it in first again.

Hi Blue,...Experts you say?? Well that leaves me out.
 
I assume the ECM controls the OD, You might try disconnecting the battery for a little while to reset the ECM,.You might also check the connection on the temp sensor we were talking about in the other thread, the one on the front of the motor above the water pump.
 
 

Thanks for the reply. I did actually try the battery trick. Although it was by accident. Alternator died on me. It runs better after the reset but from time to time i still get the od problem.

Blue, here's some info on the 4+3, seems there is a overdrive relay somewhere, and theres a switch located on the OD unit.
 
 
http://www.5speeds.com/archive/27.html

Awesome info. I found that after kicking down in first gear the OD is supposed to stay off until reaching fourth gear. Kicks down as advertised but does not re engage the OD in fourth. I think i may need a new ECM.

Hi Blue, I would exhaust all other options before buying a new ecm. My 85 has an auto, so I don't know where all the components are you need to check. Some one will come along that knows more about them.
 
Be sure to check out Crash's post in this thread.
 
http://www.corvetteforums.com/m_44272/mpage_2/tm.htm

I've heard the ECM computer chip can be programed to shutoff the overdrive in different configurations.  You might want to remove the chip and get it read.  Mine has the 180 degree theromstat/fan Upgrade. Not sure how the overdrive is programed.  Mine is also a 4+3.