I have noted that the 89 shifts into O.D. at indicated 32 MPH. I know speedo is slightly off si I fugure it is actually around 35. 94 shifts in at about 39 indicated, 89 is primarly the grocery getter around town truck, usually run at speeds up to 35 to 45, with occasional trips at 55 to 65. I was wondering if the PCM is adaptive and capable of learning? Another thing that in interesting is the 89 with 3.9 O.D. down shifts are exact to keep speeed constant. 94 with 318 will hold O.D. forever because of the higher torque but will let it slow about 4 MPH below speed setting then regain orriginal setting and back to O.D. I figure 89 is just about perfect and 94 is having a slight problem with speed sensor. Its not a big enough delta to start fixing and wa wondering how other 1st gen dacs handle O/D and speeds.

 

if you're refering to the PCM having adaptive logic where it adjusts the shift points according to the style of driving, then no. If you had a Dodge Caravan with an A604 4 speed automatic, yes because those transmissions are all electronic. The trucks on the other hand no; because the PCM only controls 4th gear and TCC. It determines when to upshift based on the TPS, MAP sensor and VSS. 1st through 3rd gears are all controlled by the transmission itself.

 

Yes the PCM does learn and adjust to lots of conditions. But like said above it doesn't control all the shifts just OD and TCC. OD is okay to come on at 32 if that is what you are getting.

If shifts are off then the TV cable probably needs to be adjusted. The FAQ has a link on how to adjust it.

 

Little 89 does so much so well. I didnt think CPU's had that ability back then. I do generally drive like the Granpa I am and I noticed the lower speed shifts into O.D. when we were Christmas shopping. Thanks for all the replies.