I'm having speedometer and hard shifting issues with my '99 6.5 diesel Suburban. I'm sure I caused it today because I just changed the A/C-Heater blower motor. To do this I had to disconnect the computer behind my glove box. First I disconnected both batteries, then I unplugged the three electrical connections to the big computer, and one other connection to a circuit board mounted under the computer. When I got the new blower installed I reversed the process. Within a few minutes my ABS and service engine soon lights came on and I noticed my speedo is not working. Also, the transmission was shifting very hard. Does anyone know what I did wrong? (The good news is my blower motor sounds and works great now.)

If you read this far and were planning to offer help, THANKS, but I found my loose connection and fixed all issues.

 

The issue is fixed! I found a loose connection and got it right.