lost tachometer and speedometer at the same time, trans won't shift into high range.

[Kawika75]

I was driving around 35 and it felt like my transmission slipped my first thought was NOOOOO !@!@$%#$@% then I noticed no tach and no speedometer. the truck runs normal but starts rough after warm up was the only hitch this 7.4 vortec really had. new fuel pump, cleaned the tank while I had it out and I cleaned the fuel side as good as I could, vacuum flush, fuel treatment, plus new set of wires and plugs. two sources have pointed towards transmission output speed sensor. I've changed the sensor and nothing. I noticed another sensor at the top of transmission I was going to change that one to for the hell of it. then another person pointed towards the ignition control module. I put a new denso module in last summer. ideas?

 

[JiFaire]

Here is a video about the problem with the Ignition Control module. Shows you a possible test.

Friggin cold-solder sensor boards...

 

[MrMarty51]

I dont have a clue what the matter could be. I just dropped in to say welcome to the forum 75.